DESIGN & PERFORMANCE WORKBOATS

DESIGN & PERFORMANCE

WORKBOATS

DAG PIKE 1933-2021 Master Seaman, Navigator, Maritime Journal contributor, friend of Seawork, maritime expert and prolific author Dag Pike, ‘crossed the bar’ in May 2021 after a sudden illness.

Dag’s reputation was peerless in the marine and maritime worlds, with expertise across a vast range of disciplines, from navigation of small sailing boats to safety in high-speed commercial marine operations. Author of over 25 papers and over 40 books, from pilot guides to instructional manuals, Dag always had a well thought out view on new marine equipment, methods, and activities.

In his later years, Dag provided several pages of content every month for Maritime Journal, but his experience was much more than on the page. For example, he was also a World Championship winning powerboat racing navigator, with several world records and record attempts to his name, including navigating Richard Branson's Virgin Atlantic Challenger on its Blue Ribband record-breaking fastest Atlantic crossing by powerboat in 1986.

His experience was also in high demand as an expert witness for court cases involving accidents at sea. Just last

2 | WORKBOAT REVIEW

week, Dag mentioned he was working on a prominent expert witness case involving a fatal RIB collision that took place last summer. Over the years, Dag’s expert witness clients included a wide spectrum of the main marine solicitors, insurance companies, the Treasury Solicitor and HM Customs and Excise. The expertise involved covered a wide range of subjects including navigation, assessments of weather and sea conditions, collisions, boat handling and driving techniques and has involved a wide range of vessels from small RIBs to large fishing boats and offshore oil vessels.

While he was prominent across a huge range of marine fields, Dag was perhaps best known for his instrumental work in the conception of the RIB (Rigid Inflatable Boat), for which he and a small team developed the concept and built an early prototype, while he was Inspector of Lifeboats for the RNLI in the early ‘60s.

A perfect example of the maxim: ‘if you love your job, it never feels like work’, Dag was still ‘working’ at age 88 in an area he adored. We have the opportunity to publish his final book.

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Contents CHAPTER ONE

Introduction

4

CHAPTER TWO

Hull Design

6

CHAPTER THREE

Foils, Fins and Air Support

14

CHAPTER FOUR

Engines

20

CHAPTER FIVE

Propulsion – The Key to Performance

28

CHAPTER SIX

The Controls

34

CHAPTER SEVEN

Electric and Hybrids

42

CHAPTER EIGHT

Electronics

48

CHAPTER NINE

Deck Equipment

56

CHAPTER TEN

Crew Comfort safety and Security

60

CHAPTER ELEVEN

Harbour, Dredging and Construction Craft

66

CHAPTER TWELVE

Search and Rescue Operations

70

CHAPTER THIRTEEN

Pilot and Patrol Craft

76

CHAPTER FOURTEEN

Passenger and Wind Farm Vessels

82

CHAPTER FIFTEEN

Autonomous Workboats

90

CHAPTER SIXTEEN

Safety and Security

94

CHAPTER SEVENTEEN

Finance and Insurance

98

CHAPTER EIGHTEEN

Rules and Regulations

102

CHAPTER NINETEEN

The Future

104

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WORKBOAT REVIEW | 3

INTRODUCTION

CHAPTER ONE

INTRODUCTION

8 A 24 metre for the German Customs with a ‘Beak Bow’ built by Baltic Workboats

The title of this book covers two categories of boat but when the word ‘Workboat’ is used it will generally refer to all types of boat that are used professionally at sea and in harbour. The workboat and patrol boat sector is one of the most diverse sectors of the marine industry and they cover virtually ever type of boat that has been developed from passenger boats through tugs and rescue craft to unmanned drones. Finding a way through this maze of designs to find the right boat for the job can be a challenge and in this book we will try to show the advantages and disadvantages of most of the concepts as well as looking at the range of equipment that is on offer for these vessels. In addition there are rules and regulations governing these craft to ensure safety and then there is the question of how to finance and insure the craft. Both workboats and patrol boats are available in a wide range of sizes from tiny RIBs up to major ocean-going vessels but in this book we aim to focus on the requirements of smaller work and patrol boats up to around 25 metres in length which come within the 200 tonnes regulation sector which represents some of the most diverse sectors of the industry.

The wider boat market in these sizes tends to be focused on the leisure sector where there is a huge range of designs with the accent firmly on style. In the work and patrol boat sectors the accent is firmly on function, having a boat that can do the job efficiently and reliably. If we go back about 30 years we find that many builders were offering variations of their leisure designs as workboats and particularly as fast patrol boats and back then, some of the leisure designs offered this possibility. Now we are seeing a major divergence between the two sectors with the leisure sector focusing more and more on style and internal volume for luxury accommodation whilst the work and patrol boat sectors have a much greater focus on seaworthiness and function. The focus on internal volume has lead to designs that have hulls where seaworthiness takes second place to

4 | WORKBOAT REVIEW

the inside volume and to designs that are focused on comfort rather than being capable of operating in adverse conditions. Whereas a leisure craft may only spend 50 hours per year underway, a workboat or a patrol boat can spend 5000+ hours per year underway so that there has to be a much stronger focus on ruggedness and reliability. This can be seen in the way that engines are derated for workboat use with the focus on continuous ratings rather than intermittent ones and where hulls are built to stronger standards and where crew comfort and safety have a much higher priority.

This sector covers an incredibly wide range of different boats and different operations and in many cases one of the fascinating things about workboats is that they can be designed for very specific operations which can influence their design considerably. The designs on offer also include a range of standard designs, a workboat format that is increasing as a means of reducing costs and because operators are demanding that builders offer tried and tested concepts, something that cannot be done with a one-off design. Historically workboats were built to one-off designs with each boat being designed and built to meet the requirements of individual operations. This was fine in the days when workboats were built in wood or steel which could be developed as one-off designs but with the advent of composites and the use of computer generated steel and aluminium hulls the case for using standard designs expanded. Standard designs also offer the prospect of shorter delivery times.

Today work and patrol boats are mainly built to standard designs whatever the material used for construction because there can be significant cost savings with this approach. It also means that the customer is getting a proven design with can be an important requirement in many contracts for the purchase of new vessels, particularly in the patrol boat sector. With a demand for a proven

8 Diagram showing the inputs required to develop a new design of workboats

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design it can be a challenge for new entrants into the workboat building sector to get off the ground and this is usually done by developing an innovative concept that may be able to offer significant advantages for certain applications. However the record of developing innovative concepts is not good as far as designers and builders are concerned but some operators have followed this path to new construction. Whilst it is possible to develop a design that can offer advantages for some operational aspects, it can often mean giving up some other beneficial aspects of design. Almost every month sees a new concept that is being proposed for a specific aspect of workboat operations but it should be borne in mind that a major breakthrough in design is very unlikely and the development of workboats and patrols boats is much more evolution rather than revolution but first the challenge offshore oil sector and now the wind farm sector have demonstrated that innovative concepts can be the job done.

Then it has to be also borne in mind that the workboat sector is generally conservative and not always receptive to new concepts until they have been well proven.

You have to consider the approach of the person who is responsible for the purchase who will often not be the direct owner. He will get no medals if the design concept that he has ordered does not fully work as expected. He is likely to be in the middle between the owner or operator who wants a boat that works and is reliable at the lowest cost and the crew who have to operate the boat who wants a boat that is safe and practical. The tried and tested concept with a standard design that has already been proven can go a long way to meeting both of these requirements and it presents the safe option.

There are still new entrants into the work and patrol boat sectors and they have the courage to develop a new design and to build a prototype that can be offered to clients for testing.

Buying a new design from the paper or computer plans is rare in this sector unlike the leisure market and for a concept costing perhaps upwards of a £1 million, it can be an expensive entry fee to the market and few buyers are likely to take this risk unless the concept can offer considerable benefits. One of the few developments that made it into the mainstream was the RIB, which was initially developed over 50 years ago and is now the focus of so many work and patrol boat applications. Such is the attraction of the RIB in many operators’ eyes that they are prepared to pay the cost premium of this type of craft when for many applications the capabilities of the concept are not required. However it does look the part and that is part of the attraction.

Amongst the new concepts that are making a slow entry into this challenging market sector are SWATHs, hydrofoils and air-support craft that employ hydrodynamic or air lift to increase efficiency. There is usually a price to pay for this type of innovation and this often comes in the form of reduced seaworthiness. We will look at the benefits and disadvantages of these concepts later in the book but none of them has hit the mainstream yet. It is the same with the move to going ‘green’ where there is a perception incentive but so far this adds to the cost of the vessel and few commercial operators are prepared to take this step. This takes us to the different approaches by the commercial and the public operator sectors where the commercial operator

Credit: Goodchild Marine

INTRODUCTION

has to make money from his boats whilst public operators do not have any financial motivation and can justify the costs by the increasing public demand for ‘greener’ operations. Lifeboats are an example where in theory only the best will do to ensure safety and reliability but the costs for this approach can be very high.

Finally there is the crew. A work or patrol boat is a workplace and so the crew has to be provided with certain facilities and protection. Noise levels are important and in faster boats shock mitigation is required. So often we see self-righting systems installed when the chances of this being required may be very small. Indeed the self-righting system itself can possibly increase the chance of a capsize but as one operator put it, “I have a duty of care to my crews so have to go down this route.”

Work and patrol boats can be a complex world where there can be so many conflicting factors in the design and operation of the boats. Rules and regulations can add to this complexity rather than simplify it and there are more and more complex tasks that designers, builders and operators are being asked to solve. With this book my aim as author with over 60 years of experience in the sector is to present all the options and alternatives in order to help those involved to find a safe and secure path through the complexity.

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8 A pilot boats coming alongside a cruise liner Centre: Bow view of a performance patrol boat

8 A pontoon workboat equipped for construction work

WORKBOAT REVIEW | 5

HULL DESIGN

CHAPTER TWO

HULL DESIGN

8 A deep vee hull showing the effectiveness of spray rails in peeling water away from the hull

There is a wide choice of hull shapes and designs for use for workboats and patrol boats and this is one of the more innovative areas of design development. The choice narrows down quite a lot when you look at the job that the boat has to do and many of the designs are developed around the work involved. For any boat that has to take to the open seas then a planing monohull is likely to be the choice with the exception of the catamarans used in the offshore wind sector and often for survey and similar duties where deck space is important. Monohulls may also be the choice for inshore and harbour work but here they may well be heavy displacement monohulls such as those used for tugs and construction craft but because harbour craft are much less likely to be exposed to rough seas then there is a wider range of choices available.

Added to this mix there is a wide range of specialised designs focussed on a specific function such a dredgers and buoy handling vessels.

DISPLACEMENT HULLS Traditionally workboats were based on displacement hulls, those that go through the water rather than planing on the surface. The smaller tugs and workboats such as those multi-role harbour craft that are used for handling moorings but may have to operate as a back up pilot boat or a tug are found in many smaller harbours where the cost of 8 Giving the water moving away from the hull an easy path will contribute to a smooth ride

6 | WORKBOAT REVIEW

dedicated vessels for each role cannot be justified. Fishing vessels, of course are almost all based on displacement hulls and then there are smaller designs such as mooring boats and marina workboats. The common theme running through most of these modern displacement workboats is that they have to have a towing capability and for that you need a heavy duty hull that sits well into the water so it has a ‘grip’ to balance against the pull of the tow rope. Of course draft may also be a consideration for many of these workboats particularly in smaller harbours but in general the hulls are designed to allow a large diameter slow turning propeller that will give maximum efficiency and bollard pull at slow speeds.

Almost all ships these days are fitted with a bulbous bow which effectively increases the waterline length and helps to reduce the pitching motions of the hull and we see this trend extending to some displacement workboats, notably fishing boats where it can improve the efficiency of the hull but you rarely see them on harbour craft because they will not be operating at full speed for any distance and the bow shape could interfere with some boat operations. Fitting a bulbous bow also complicates the construction so the justification for one has to be balanced against the cost.

PASSENGER BOATS Many passenger boats also use displacement hulls as the basis for their designs although the trend now is towards catamaran hulls that allow a much larger deck area for the passenger accommodation. With passenger boats tending to operate in harbour or at least to and from harbours the question of wash has to be considered and so on monohull passenger boats the trend was toward longer and narrower hulls that would offer boat better efficiency or higher speeds along with relatively low wash. The passenger boat

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HULL DESIGN

market is one that is evolving quite rapidly and in addition to catamarans there is a growing demand for speed in transit but tourist boats still tend to operate at lower displacement speeds. When we look at the current market though, whilst the move is towards higher speeds this has to be balanced against the increasing demand for ‘greener’ boats, particularly those operating in harbours and the long narrow displacement workboat may provide the simple answer to meet this requirement.

PATROL AND PILOT BOATS When it comes to patrol and perhaps pilot vessels that have to work offshore then the deep vee monohull is the first choice. Before the deep vee was developed to its present state, these offshore craft would have been constructed on displacement hulls where the speed was limited to around 10 knots because these are hulls that go through the water rather than over it as is the case with planing boats. From displacement hulls there was a move into semi-displacement hulls where the speed potential was limited to around 25 knots maximum. These semidisplacement designs were greatly favoured as pilot boats at one time because the aim of the concept was to combine the merits of the seaworthy displacement hull with the speed potential of a planing boat. Semi-displacement hulls are still used for some large patrol boat designs where they work effectively but the deep vee hull can also be affective in larger sizes. As so often happens with a compromise design such as this, the semi-displacement hull did not match the benefits of either of these alternatives where smaller craft are concerned and it has now been replaced almost entirely by the deep vee planing hull that has proven to be capable of operating effectively at both high and low speeds. An endorsement of this is seen with lifeboats, where most of the World’s fleet of fast all-weather lifeboats is now based on deep vee hulls.

A deep vee hull is one where the bottom surfaces are shaped to form a vee when you see it in cross section. It is the angle of this vee that will play a significant part in the performance of the boat in waves because this vee or deadrise angle will determine how much the hull is cushioned against wave impact which can be important when operating offshore. It is not exactly rocket science to appreciate that the deeper the vee the more the ride will be cushioned. A well-cushioned ride will make life more comfortable for the crew who will be insulated from wave impact to a considerable degree.

DEEP VEE HULLS Like most things with boats, it is not quite that simple. You could have a deadrise angle of say 20° or more and that would work well as a cushion against wave impact but it would also require more power to achieve the same speed. p You lift to get as much of the hull outt of the water to reduce the frictional resistance as possible and to allow efficient progress and a flat bottom is the most ost efficient. Once you introduce a vee into the bottom of the hull then the lift generated is not directly upward butt is partially deflected sideways. That provides the wave cushion but is not ot so good for lift and so requires more power ower so a compromise solution has to be found und and for most patrol boats this is likely to be between 12 and 20°. w effective a deep What has surprised many is how

vee hull can be at slow displacement speeds because after all, for a boat to be practical it may have to operate at both high and low speeds in the open sea. So these days it is not so much a question of whether to have a deep vee hull but rather what angle of deadrise should be used. The deeper the deadrise the better and more comfortable the ride but the deeper the deadrise the less efficient is the hull and more power is need for a given speed. A good compromise for the deadrise would be around 15° on a patrol boat but on a smaller craft such as a RIB a deadrise of 20° or more would be appropriate. Generally the smaller the boat the more deadrise you need because small boats are much more susceptible to wave influence. But the story does not end there.

On some designs the designers will introduce a deep vee and then compensate for the reduced efficiency of a deeper vee by introducing wide chines. These are flat surfaces that are placed where the bottom of the hull meets the topsides and they are there partly to help stabilise the hull but also to generate more lift. On an offshore boat these chines should be no more than about 10 cms in width otherwise this flat surface could also generate heavy wave impacts. Like everything to do with boat design the designer has to find a compromise and one solution is to have a double chine.

Today we are seeing deep vee hulls where the deep part of the vee is focussed in the bow area and where in the aft part of the hull it flattens out to a shallower vee. There is a lot to be said for this sort of compromise hull because most offshore craft of larger sizes will not be driven to the point of the hull leaving the water and the flatter vee aft which is the main surface g generating g lift,, makes the hull more efficient.

BOW SHAPES It is in the bow shape that we see the major difference between leisure and working boats. A As we have said, leisure boats require internal volume whereas in working boats, performance and seawo seaworthiness will normally take priority. A fine entry a at the bow combined with a generous flare in the topsides will out-perform a full bow shape in rough seas and be lless sensitive to wave motions a and impact. For rough sea op operations the bow shap shape is the key to

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ne news101

8 Profiled foam tubing applied to a RIB hull

8 Left: A trimaran hull showing the slim hull shapes that can improve efficiency

WORKBOAT REVIEW | 7

HULL DESIGN

8 The transverse framing structure of a metal hull

8 Right: A practical displacement working boat with a clear aft deck

performance and whilst the focus tends to be on operations into head seas, following sea can be a challenge as well with the bow wanting to bury into the wave ahead as the boat comes over a wave. This is why flare in the topsides at the bow can be important as in allows the buoyancy to increase as the bow becomes immersed. Another solution is to have an ‘anti-stuff’ bow which is flat surfaces introduced in the bow close to the deck line which slope upwards towards the bow to provide a considerable increase in both buoyancy and lift before the deck would become immersed.

The basic hull design found on a deep vee hull can be affected by quite a few more subtle variations. The designer has at his/her disposal attachments such as spray rails and chines, bulbous bows and flat bottom pads that can be used to vary or improve the performance and capability of a hull. The Beak Bow, which is a planing variation of the bulbous bow is an example of an innovative design that is favoured in some quarters. Most designers have their own thoughts about these options on standard hull designs which have to be a compromise but when designing a one-off workboat the hull shape can the tailored to the expected conditions and employment.

HULL STEPS Where higher speeds are required from a deep vee hull as in fast patrol boats and interceptors it is becoming common to introduce steps into the bottom of the hull. A normal deep vee hull will ride of the planing surfaces towards the rear of the hull as it comes onto the plane with a balance between the position of the centres of gravity and buoyancy and the lift generated by the planing surfaces of the hull. This balance can be the cause of some pitching of the hull as the three factors involved try to find a common balance and by introducing steps into the hull the lift factor of this balance is spread along the hull and this can help to reduce the pitching as well as creating a more efficient hull at higher speeds. Hull steps tend to become a viable option at speeds over 40 knots and allow the boat to ride at a more level attitude with reduced pitching.

SEAWORTHINESS Whilst speed may be an important factor in many patrol boat requirements and it is easy to quantify and check on trials, seaworthiness can be just as important as far as

8 | WORKBOAT REVIEW

offshore operations are concerned but is much harder to quantify. This can be why many contracts for new patrol boats will require a proven hull design that can be tested in how it performs in the open sea but requiring a proven hull design can also restrict development because new concepts have a major cost hurdle to overcome in building a prototype. Then again, seaworthiness is not just a matter assessing how the boat performs in waves because so much of the performance of a fast boat in the open sea is in the hands of the person driving the boat and a skilled driver can make even a poor design perform reasonably well. This driver tends to be the big unknown factor in fast boat design and like seaworthiness it is hard to quantify driver skills. Tried and tested designs are therefore the best solution on offer in many cases.

Obviously any deep vee hulled boat could operate as a harbour or river craft where speed is sometimes required with a boat that is used on enforcement roles but with a focus on environmentally friendly issues, a more fuel efficient hull might be appropriate. A lot would depend on the size of boat required but with a limited requirement for seaworthiness a good option could be a cathedral hulled boat in smaller sizes or possibly a catamaran with slim hulls for larger sizes. The latter might be a good option where having a hull that creates a low wash is required and low wash patrol boats are becoming a requirement for many river based authorities. This is likely to be an expanding part of the workboat sector in the future and low wash and fuel efficiency tend to go hand in hand where environmental factors have to be considered.

CATHEDRAL HULLS Boats with a cathedral hull have a relatively flat bottom with two embryo side hulls that help to widen the hull to create an expanded working area on deck. As small harbour patrol and work craft they work well and are efficient, usually powered by an outboard motor. They are rarely used in larger sizes except for some fast fishing boats, mainly because the bow shape in not particularly wave friendly unless the boat is fully on the plane when the bluff bow lifts clear of the wave crests. These cathedral hulled boats tend to look like trimarans at the bow but now we are seeing a reverse type of hull where the boat has a conventional bow shape but the chine as it runs aft becomes a reverse chine that almost develops into what look like embryo side hulls that generate more lift aft.

SEMI-DISPLACEMENT HULLS This concept is a feature of the Slide Hull developed by Vripak which is claimed to offer much better seaworthiness that a conventional hull but this Slide Hull is based on a semi-displacement hull which is a sort of compromise between the planing and displacement hull designs and is aimed at retaining the sea-going characteristics of the displacement hull whilst allowing higher speeds. These semi-displacement hulls were very popular a few years back as pilot boats and for some patrol boats and they featured relatively narrow hulls with a flat bottom for planing but with rounded bilges to avoid the harshness to the fully planing boat. They offered speeds up to about

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HULL DESIGN

25 knots before excessive power was required. One advantage of these semi-displacement hulls was that they were fitted with a skeg to give directional stability and this offered some protection to the propellers in the event of striking debris or grounding. Semi-displacement hulls were notable for their bow up attitude at speed and many designs generated excessive spray which could hamper visibility and today they have largely be replaced by deep vee hulls. The Hull Vane was developed to improve the performance of semi-displacement hulls and this aerofoil strip fits across the transom in the water flow from the propellers and serves to maintain the hull at a more level attitude as well as improving fuel consumption.

WEIGHT DISTRIBUTION With planing boats the weight distribution inside the hull can be important and following on leisure boat practice most of the machinery weight is concentrated aft to allow maximum space for accommodation. On workboats where the internal space is not such an important factor there can be benefits in moving the machinery and fuel tanks further forward which can help performance in head seas, particularly with semi-displacement hulls. As always with boat design there has to be a compromise and this is mainly up to the designer. Bow ballast tanks are one solution that can be used to vary the position of the centre of gravity according to the sea conditions and flaps can also be used to vary the fore and aft trim LANDING CRAFT Landing craft are a significant sector of both the commercial and military sectors and they features craft capable of landing on open beaches with a bow ramp. The concept requires a rectangular deck shape to be married to a seaworthy underwater hull and it is usual to find recessed propellers for protection when beaching or the use of water jet propulsion. The downward thrust from water jets going astern can be a useful feature when getting off the beach as this generates lift when reversing. Water jets can also allow landing craft to have planing boat speeds which is an increasing requirement particularly for the

military. Landing craft are a good example of the many specialised types of workboat that have been developed over the years to meet specialised requirements. The pontoon workboat is a similar specialised craft but here the development is to create a working platform for marine construction work. Here the hull is rectangular in plan view with either fixed shaft and propeller propulsion or where a shallow draft is not so critical, a type of heavy duty pod propulsion which may be retractable.

8 The hull shape of a displacement catamaran with conventional propulsion

RIBS One area where we have seen a dramatic change in workboat design was with the development of the rigid inflatable, the RIB. When we started to build RIBs over 50 years ago we were working in the dark. Between the RNLI and Atlantic College over 12 prototypes were built until we found a solution that worked. Our yardstick for comparison was the 15 foot fully inflatable rescue boats that were in use with the RNLI at the time and the requirement was to find a rescue boat that was both more durable and offer better performance. The fact that basically the same design 8 A monohull wind farm vessel with extended bow for tower engagement

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WORKBOAT REVIEW | 9

Credit: Damen

Credit: FB Design

HULL DESIGN

8 A monohull multi-purpose workboat capable of towing and construction work Right: A semi-RIB coastguard boat with anti-stuff bow shape tio improve performance in following seas

of inflatable rescue boat is still in use with the RNLI as their D-Class boats is an indication of how good these small inflatables were so in developing RIBs we were trying to find an even better solution.

Those first RIBs, which developed into the famous Atlantic 21, worked well and demonstrated greatly improved seaworthiness compared with the inflatable rescue boats. Once they became operational it was time to study why they were so good and four important factors were identified which were the deep vee hull, the tube pressure and the tube location. The fourth was the introduction of the saddle seat which allowed the helmsman much better control and a quicker control response.

These are the factors that define RIB performance.

The deep vee hull was important for a RIB because that was the area that give the boat it longitudinal strength with some of the failures of the early RIBs being lack of this strength. Of course the deep vee also cushioned the ride which was a dramatic improvement over the flat-bottomed inflatables. We found from trials that tube pressure was also important with a modest tube pressure of around 2 psi allowing the tube to deform under wave impact and absorb some of the shock loadings of this impact.

This introduced a form of variable geometry into the hull design, allowing the hull shape to change momentarily according to the conditions and allow a smoother ride with reduced hull impacts.

There were two aspects of tube location in relation to the rigid section of the hull that were variable and important for optimising performance. One was the height of the tube in relation to the waterline and here the best location was with the tube slightly clear of the water when the boat was at rest. This location meant that the tubes would give good stability when the boat was at rest or operating slowly which was a bonus for rescue work and at this height the tubes did not generate additional drag from the interaction between the tube and the water as the boat lifted onto the plane. The other aspect of tube location was the angle formed between the tube and the rigid section of the hull.

This angle should offer the water a relatively smooth path as it moves outwards from the rigid section and around the tube in waves in order to minimise the wave impact.

Modern materials and adhesives allow high tube pressures to be used on modern RIBs. It is suspected that

10 | WORKBOAT REVIEW

this is done mainly to improve the appearance of the tube and to remove any wrinkles that might be in the tube through trying to accommodate compound curves into the surface of the tube. High tube pressures will prevent the tube from varying its shape under wave impact so that aspects of the variable hull geometry found on early RIB designs are lost. Perhaps more significantly a high tube pressure will cause the tube to bounce rather than deform under impact and this can have several detrimental consequences. Firstly in waves, if the tube bounces on impact it will cause a sudden movement of the hull that can lead to sharp lateral motions of the boat that will then impact on the crew. In severe cases of bounce the tube can cause it to bounce from side to side on the tubes, a phenomenon that can only be cured by slowing down.

Secondly this bounce effect can affect trying to berth the boat alongside. In this situation the boat can bounce off as it tries to come alongside making berthing challenging. In harbour this may not be a major problem but bounce can be a problem when trying to come alongside another vessel at sea such as on rescue, boarding or pilotage operations and it could compromise these operations. On many modern RIBs the tubes are mounted too high on the rigid hull so that the stabilising effect of the tube at low speed is not effective until the boat heels over to a considerable angle. In this situation the hull will then perform like a conventional deep vee and many of the RIB attributes are lost.

8 Catamaran combine large deck areas with economical performance

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HULL DESIGN

For many RIB operators in the commercial sector performance in waves may not be a critical aspect of their performance but with the modern focus on health and safety anything that introduces a harsher ride into the operation can be important for crew comfort and safety. This has led to a proliferation of various designs of sprung seating designed to absorb the shock loadings of the RIB hull. Sprung seating does a good job but with many modern RIB designs a solution to a harsh ride could be found by modifying the basic design.

So RIBs have changed a lot since they were first developed and we are seeing them used in a wide variety of workboat roles where the seaworthiness attributes of the RIB are not necessarily required. RIBs rend to be more expensive that other concepts and in most cases the tubes is there simply as a fender. Inflatable tubes are being replaced by resilient foam tubes which can be more durable but they can also offer a sudden change in hull shape above the waterline which can increase impacts in waves. We also have to look at the dramatic increase in size that has occurred over the years and it is questionable whether a

The long, thin hulls of the conventional catamaran have been taken to extremes with some advanced designs that use very slim and longer-sided hulls to increase efficiency

‘‘

monohull because of their reduced wave-making resistance.

Chines may be added to help peel the water away from the hull and a vertical bow or even bulbous bows may be fitted to help increase the waterline length.

The planing catamaran also features long, narrow hulls, but these are fitted with planing surfaces underneath so that they generate lift. In its simplest form, the planing catamaran is a deep-vee hull cut in half longitudinally and with a cross deck fitted between the two hull sections. Air lift generated by the air pressure induced between the hulls

8 A performance diesel powered military RIB

RIB in larger sizes really works and offers adequate benefits for the extra coast and weight.

Variations in RIB construction materials have also been used for workboat applications. One of the first was to replace the inflatable tubes with aluminium tubes in roughly the same shape as the inflatable would adopt but this offered no real advantage apart from the reserve buoyancy contained in the tube. The additional reserve buoyancy that is found in a RIB is a bonus as far as safety is concerned but it can often be found at the cost of a harsher ride. Another solution for RIB type boats is to use heavy duty polyethelene plastic and this has been adopted by some builders both to replace RIB tubes and also to construct complete boats. The benefit is the claimed long durability of the material and its ability to absorb rough treatment but the ride can be harsher that that of a conventional RIB. MULTIHULLS Multihulls are being used widely in the workboat sector but mainly in applications, that required a large deck area such as a working area or for increased passenger space. Like all boats, multihulls come in a wide variety of shapes and sizes, but the main difference is found in the side hulls, which can be either displacement or planing types.

Displacement catamarans are based on long, thin hull technology with a length/beam ratio for the side hulls that support the craft being something in the order of 8. This allows them to slip through the water easily with minimum resistance, and with only moderate power they can achieve speeds that might be double that of a displacement

at speed can help the performance and they will often go faster into the wind than downwind. This air lift also has the benefit that it can help to moderate the hull motions in adverse sea conditions. Planing catamarans can offer very high speeds but have not played a major part in work and patrol boat operations with most of the wind farm crew transfer designs being displacement catamarans.

The long, thin hulls of the conventional catamaran have been taken to extremes with some advanced designs that use very slim and longer-sided hulls to increase efficiency.

Probably the best example of this is the wave-piercer hulls that were developed initially in Australia and whilst the focus of wave piercers is on larger passenger carrying craft there are some smaller designs in the wind farm sector.

With all catamarans, the limiting factor in their operation can be when waves start to impact on the flat underside of the cross deck. This will normally mean that the boat has to slow down and as it slows down it then drops in the water meaning that the impacts can increase. The results in catamarans having a fairly sudden cut off point between being viable and having to reduce speed considerably to cope with conditions. For wind farm transfer operations the catamaran works because the actual transfers can only be made in moderate conditions where the catamaran hull works well and efficiently.

Then there are trimarans and even four hulled craft.

Trimarans with slim side hulls balancing a slim deep vee hull are a viable alternative to the monohull but in general they have very limited application in the workboat sector although some have been used as patrol boats.

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WORKBOAT REVIEW | 11

HULL DESIGN

Credit: FB Design

8 An advanced very high performance lifeboat design with casualty recovery systems

CONSTRUCTION MATERIALS In terms of construction materials, steel in widely used for displacement hulls and for some semi-displacement designs. These days the steel is cut under computer control to give a very accurate shape to the completed vessel and modern coatings can greatly reduce the impact of corrosion on the hull. Aluminium is used in much the same way but the lightness of this material means that it is viable for planing hulls and is often found where one-off designs are required that do not justify the high cost of a mould as would be the case when using composites. Care needs to be taken with aluminium as far as various conflicting metals used in the boat are concerned so that electrolysis is not a problem which would tend to cause corrosion in the aluminium but this process is now well understood and is not a major problem. We are also seeing aluminium used for the superstructure on steel hulled boats where a reduced weight is required.

Composites are used widely in work and patrol boats for hull construction, often using advanced composites such as Kevlar and carbon fibre in place of the normal glass fibre 8 The slim hulls of a displacement catamaran

12 | WORKBOAT REVIEW

where high strength and weight saving are required. Kevlar can bring increased strength in tension to a laminate whilst carbon fibre composites tend to be used to cope with compression stresses. So much of the hit and miss has been taken out of composite construction these days so that hulls are fully engineered to cope with the high stresses of fast boat operations without adding excessive weight. Even so the hulls of most fast boats are over-engineered because failure is not an option and the stresses of fast boat operations in rough seas can be hard to quantify with very high peak loadings possible.

The use of composite construction is only viable when the high cost of the plug and the mould can be amortised amongst a series of boats rather than just a single hull. It is possible to build a single hull in composites but this is very rare these days where many contracts will require a proven design where the cost of the mould can be justified.

Construction of the hull in a mould still allows different types of composite construction to be used such as foam or balsa cored sandwich construction and there are ways that the basic mould can be modified to accommodate features such a water jet propulsion and variable lengths. This type of construction can be beneficial in terms of reducing the noise levels from the hull but it does require high standards to achieve good and reliable results.

For workboats and patrol boats that are to operate in the fast boat sector, which would normally be above 30 knots the most popular approach is the make boats lighter in the quest for speed. Hull structures are designed with the minimum weight that is compatible with reliability and all of the other parts of the boat and its structure are reduced to an acceptable level of weight reduction. It may be the logical approach when higher speeds are required but it may not always produce the best boat for the job particularly when the boat has to be capable of operating in rough seas. A lightweight boat will produce a much livelier ride when travelling fast in waves because of its lower inertia whereas

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HULL DESIGN

a heavier boat with more power should be able to travel faster in the same conditions because it will be less susceptible to the waves. This has been noticeable in offshore powerboat racing where a heavy diesel powered boat is matched to a lightweight petrol powered boat. They may have around the same top speed in calm conditions but the diesel boat has a much better ride and always be able to maintain a better speed in the rough. The penalty of course for fast patrol boats is the higher fuel consumption and probably the higher cost. You see this with the modern approach to using a multiple lightweight outboard motors as power units which allows much more space inside the hull but the penalty is the livelier performance in waves. This is a case where the buyer may have to make difficult choices.

Whilst standard hull designs are offered by most of the composite work and patrol boat builders these days, there can be variation in the superstructure to meet the requirements of different applications. Some builders will offer a range of superstructures also made from composites to fit the standard hull whilst others will offer superstructures in aluminium that can be individually tailored to requirements. Designing the superstructure and the detailing of the boat is just as important as the hull design and to achieve a reliable and workable package for the completed boat needs considerable experience which is why the workboat and patrol boat markets are not easy to enter as a

start up. In addition to the experience required there is the high cost of building a prototype because these days it is almost impossible to sell a new design from the drawing board and the term ‘proven design’ keeps coming up. For the operator trying to get the right boat for the job that it has to do is an equal challenge and requires experience and this should start with the hull design because that is where the basis of the boat’s capability starts.

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8 The favoured design of a wind farm service boat based on a catamaran hull

WORKBOAT REVIEW | 13

FINS FOILS AND AIR SUPPORT

CHAPTER THREE

FOILS, FINS AND AIR SUPPORT

8 The Ghost, an experimental high speed SWATH type vessel for the US Navy

There has been an endless quest to make boats go faster and more efficiently and in the light of modern concern about the environment, efficiency is much more in focus.

Obviously you can make boats go faster by adding more power and in the last chapter we could see how this could have benefits in terms of a heavier boat having better seaworthiness. However this can have a negative effect on fuel efficiency and an alternative way to make planing boats go faster and be more efficient is to reduce the wetted surface area of the hull that is in contact with the water and there are various ways this can be achieved. A number of new concepts are being promoted and whilst most of these work effectively there is usually a downside to these developments as far as workboat applications are concerned and their application may be limited. However in the future there may be added pressure to promote fuel efficiency and some of these may be the route to follow.

HYDROFOILS Probably one of the earliest of these systems was the hydrofoil, which used a series of foils attached to the hull to generate lift and thus raise the hull clear of the water. These date back to some early planing designs and there is no doubt that hydrofoils can offer considerable potential as a design technique for fast powerboats but they also have considerable disadvantages and on balance they have never realised their promise particularly for smaller craft up to say 25 metres. The foils act like the wing of an aircraft and they generate sufficient lift from the forward speed of the vessel to lift the hull. The foils themselves are much more efficient lifting surfaces than the hull of a planing boat and once foil-borne the ride can be remarkably smooth because the hull is largely isolated from the waves.

However it does not take a lot of imagination to picture that once the waves are large enough to start striking the bottom of the hull then the speed and effectiveness of

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hydrofoils is reduced. The use of hydrofoils has been generally restricted to passenger craft on rivers and lakes where the wave impacts are not a problem. There is also the problem of increased draft when the boat is at slow speed or stopped and the hydrofoils may stick out at the side of the hull both of which can be a significant handicap for berthing.

Now we are seeing a new generation of hydrofoil craft using retractable foils that offer a much more practical solution. Whilst this development is mainly in the leisure sector at present it may offer solutions in the work and patrol boat sectors perhaps initially in thrill ride boats and in river and harbour passenger boats where the low wash characteristics of the hydrofoil could allow high speeds in restricted waters. With this new generation of retractable foils it does offer the operator the option of operating as a conventional boat when not foil borne. This new generation of foils is constructed from advanced composites which allow the complex shapes to be more easily developed and reduce the need for supporting structures. Another development in foil use is to have trim flaps like an aircraft to fine tune the lift so that the boat will have a level ride but whether this added underwater complication can be justified is still open to question.

With the fully submerged foils the lift generated increases with the speed but they make for a complex and expensive craft and the fully immersed foils can be vulnerable to debris in the water. One of the major problems with the design of these hydrofoils was with the propulsion system where it can be a challenge to keep the propeller in the water as the craft lifts up onto the foils. It can mean a steeply angled propeller shaft or a complex water jet system neither of which are particularly efficient but electric propulsion may provide a solution with the motor installed close to the propeller.

The alternative to these fully submerged foils is the surface piercing foil and these are found on most modern leisure hydrofoils of the retractable type. Propulsion still

8 An air-supported wind farm service catamaran aimed at giving greater efficiency

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FINS FOILS AND AIR SUPPORT

8 An experimental air supported monohull design at speed

Now we are seeing a new generation of hydrofoil craft using retractable foils that offer a much more practical solution

‘‘

remains a challenge when the boat lifts in the water and there is so far no easy solution although new drive systems such as pod drives may provide a solution. Hydrofoils have their place in fast boat development but they have been larger overtaken by developments in conventional hulls although new foil technology may see a revival. Foils are also used on catamaran hulls, attached between the two hulls and these can not only generate lift but they also help to damp out wave reactions but in rough seas the foils may plane on the surface rather than remain submerged.

An interesting use of foils is in the Wavefoil system where a pair of foils can be lowered from the bow and are allowed to articulate up and down. This not only helps to damp out any pitching motions of the bow but has also been developed to produce useful thrust. At the time of writing this system has only be tried on large vessels operating a ferry service with some success but a 22 metre catamaran is being built with the system as an ambulance boat and this experience may open the door to its wider use on patrol boats.

AIR LIFT What the hydrofoil has done with lift generated from the water the catamaran has done with lift generated from the air. This does not work with monohulls but catamaran running at speed can generate useful lift from the air passing under the hull and through the tunnel. On some very high speed catamarans the cross deck is given an aerofoil shape to exploit this lift but if the hull is rising and falling in waves the air flow is disturbed and the lift diminishes.

An interesting new approach to using air lift is seen with the Advanced Aerodynamic vessel (AAV) which has been developed in France by A2V. Their prototype vessel had two widely spaced hulls in catamaran style and these are linked by an arched cross deck that forms a giant aerofoil with the pilot house located inside this aerofoil or just above it. The bottom of this aerofoil is virtually flat and is quite high up above the water whilst the upper section follows a full curve to create the aerofoil section that tapers down at the rear. It is certainly an unusual type of craft but following extensive trials with the prototype that was 10 metres long and capable of 60 knots with a pair of 200 hp outboards for

propulsion the company has received commercial contracts for passenger craft.

The AAV exploits the possibilities of using air lift to the full with the side hulls located well apart in order to maximise the wing lift effect. The side hulls are quite narrow planing hulls with steps to reduce the wetted surface area and when running at speed these hulls only skim the surface. What is interesting about these AAV designs is that whilst they exploit the possibilities of using air lift to the full they have a good sea-going capability, mainly because of the high clearance under the wing so that they can operate in adverse conditions which is the Holy Grail of fast boat performance. The economical performance of these designs will obviously appeal to commercial users but as always with a new concept the take up is slow and at present has been used for passenger carrying.

WIGS One step further down the line for using the air lift generated from forward motion is the WIG - Wing in Ground technology. To all intents this is an aircraft and in many ways like a seaplane but it only flies very low above the sea surface because it generates its lift mainly from the close contact with the sea surface. An aircraft flies in the open air but the WIG relies on the ground effect, the extra lift generated when an aircraft flies close to the ground or the sea surface. WIGs are now classed as sea-going craft and they are mentioned in the Colregs because there is a need for them to take avoiding action from regular shipping and boats. The WIG can operate very effectively at moderate speeds over water and it takes off and lands from the water so it has a sort of boat shaped hull with relatively short, usually stubby wings that are designed to generate lift at low speeds. Obviously because they are flying they tend to be weight sensitive so lightweight construction is essential and modern versions tend to be constructed in composites with power from lightweight aircraft rated petrol engines driving through an air propeller.

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8 The Hull Vane fitted to a semi-displacement hull for improved efficiency

WORKBOAT REVIEW | 15

FINS FOILS AND AIR SUPPORT

8 A Russian hydrofoil passenger vessel on the Moscow River

Whilst there are several companies building WIGs and trying to market them, it does appear that the commercial sector is not ready for this level of advanced design and WIGs are a concept looking for a role. On paper the potential is considerable both for transporting passengers and cargo over short and moderate distances where the speed would allow them to compete with expensive aircraft rather than boats. It is not just a question of the design of the craft, which is now quite advanced but it is in developing the infrastructure and confidence to make them a viable transport alternative. There is also the question of collision avoidance between these very high speed craft travelling at perhaps 100 knots and conventional vessels on the water.

8 Side elevation of a SWATH wind farm service vessel

HOVERCRAFT We have seen much the same thing with hovercraft. They were launched as a revolution in transport, a craft capable of operating over land and sea at speed but they have developed only limited and specialised applications over the years. The concept is simple, introduce a cushion of air underneath the hull and let the craft ride on this cushion which was contained by a flexible skirt, which would greatly reduce the friction between the hull and the sea surface and allow the craft to slide across the water. The air cushion vessel or hovercraft was not confined to the water either but could cope with beaches and other relatively flat surfaces. It is easy to see why it was hailed as a revolution but trying to translate the basic concept into a practical

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craft proved challenging and the hovercraft has never really lived up to its promise. The early development faced two challenges. Firstly because the craft was not riding in the water but above it, it was classed as an aircraft and so it had to meet aircraft standards and specifications and the crew had to be pilots which of course put the costs up considerably. Secondly it relied on flexible skirts made from a rubberised fabric to contain the air cushion and these were subject to considerable wear and tear. Air propellers were required for propulsion which generated a lot of noise and with no ‘bite’ on the water, control could be challenging particularly in cross winds rather like the WIG. These pure hovercraft found a few niche applications and were particularly suitable for use in ice covered waters and swamp areas. Some passenger services were operated and still continue to this day. Once the ‘aircraft’ designation was removed the costs reduced and diesel power became viable but the wear in the flexible skirt was still a problem. This led to the development of the sidewall hovercraft where the air cushion was contained between rigid side hulls with flexible skirts just at the bow and stern. This configuration gave the craft many more of the attributes of a sea-going vessels with the sidewalls giving the craft directional stability and a ‘bite’ on the water whilst the smaller skirts reduced maintenance costs and marine propulsion systems could be used. However these advantages were balanced by the craft being able to operate only over water. Craft of this type are coming into use in the wind farm sector for crew transfers where they are claimed to be more efficient than conventional catamarans.

The next stage of development was a craft with air lift from fans but no flexible skirts. This was achieved by shaping the underwater parts of the hull into an air chamber where the air cushion was contained within the rigid hull structure. This greatly reduced maintenance without compromising the sea-going ability creating a super-efficient hull. This is the stage of development where we are now and with the focus on reducing emissions efficiency may lead to expanded use of this type of hull particularly for passenger carrying where the hull efficiency can make electric propulsion more viable. Currently the concept is being exploited by Effect Ships International in Norway and with considerable research funding and development work including extensive tank testing they

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FINS FOILS AND AIR SUPPORT

SWATHS A bit more successful in the commercial sector has been the SWATH. This stands for Small Waterplane Area Twin Hull and the idea here is to put the buoyancy that supports the craft below the surface of the sea and connect it to the main deck above water by a slim vertical structure with minimal buoyancy. This means that the passing waves would only have a small effect on the overall buoyancy of the craft as they pass through the vertical support legs of the structure meaning that the SWATH would maintain a stable and level ride. SWATHs are now a well proven concept and are operating as pilot transfer craft, CTVs for wind farms and in other workboat roles where a stable platform is required.

Like all new developments the SWATH has a downside with the costs for a SWATH working out considerably high than for a conventional craft of similar size. They also have to be built to a minimum size with the limiting factor in reducing size being accommodating the engines in the torpedo shaped underwater sections and the access down to these area via the vertical supports. This may change with the advent of electric propulsion which is more compact and requires no air intakes or exhausts but so far the applications of this technology are limited to mainly pilot boats and offshore passenger transport where stability can be important. Also the SWATH concept only works on craft perhaps over 20 metres of so because the gap between the lower buoyancy and the upper deck is too small on smaller craft so waves could quickly strike the under deck as conditions deteriorated. SWATHs are also more expensive than a conventional hull so they can only be justified where the benefits are obvious and tangible.

Most SWATH designs have had the two underwater hulls in parallel as in a catamaran form but another option that has been tested is to use a trimaran or SWASH format.

These use three hulls but none of them run for the full length of the craft and there is one forward and two aft in tricycle formation which economised on the structure. The system worked but again the complication of the structure and the cost did not justify the investment except for special applications. Another version uses a full length centre hull with slim side hull for stability in a trimaran form.

CTVS The introduction of offshore wind farms has led to some owners prepared to experiment with some of these alternative hull designs. These wind farm craft have to get technicians and work crews out to the wind farm structures often in adverse conditions. The passengers on board want as smooth a ride as possible to reduce fatigue and sea-sickness and so there can be some justification in the higher investment in alternative designs if it gives a rough weather advantage. The

Credit: A2V

produced a very effective air supported concept. At the time of writing Tuco Marine, a workboat builder in Denmark is the only builder who is exploiting this technology commercially but it has a lot of promise for future workboat design. An electric only powered version can achieve 30 knots for short periods and with a fast charging system could make a viable commuter transport system.

standard designs all use catamarans and in most cases these provide an effective means of passenger transport in the sort of conditions where the passengers can be transferred onto the wind farm structures. This reduces the incentive to invest in more expensive concepts that might offer better rough sea performance or higher and perhaps more economical speeds and recently an SES has been trialled as have SWATHs with some success but as so often happens it is the tried and tested solution that finds favour in the hard commercial world. Higher costs of some of the more complex designs have to be balanced against the maybe limited advantages that they offer but as these wind farms become more established in more exposed sea areas then more seaworthy concepts might be justified.

AMPHIBIOUS CRAFT Finally there are amphibious craft that can operate on both land and sea. These designs mostly stem from the DUHK craft developed during World War II and again here we have a craft that is going to be more expensive that a conventional design but it will do something that the others can’t, make the transition from land to sea or vice-versa, and having the possibility of becoming a viable road vehicle. It is easy to see the attractions of such a craft but the complications involved will often outweigh any advantage in the operation.

One of the best known types of amphibious craft is the Sealegs RIB which has a single wheel forward and two aft with these wheels hydraulically driven using power from an auxiliary motor in the boat. The wheels are retractable and to come ashore you simply lower the wheels as you approach the beach or slipway and when they make contact with the beach you drive ashore. The wheels and their hydraulic systems add quite a bit of weight to the boat so there is a reduction in performance but unlike most other systems the Sealegs system has all of the road going system out of the water when afloat and propulsion is by a conventional outboard on the transom. Whilst the company previously built their own RIBs and sold a complete package they are now licensing the system to other boat builders so we are likely to see more of this innovative system.

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8 An advanced Aerodynamic Vessel (AAV) at speed

8 A SWASH design with the central hull providing buoyancy and the side hulls stability

WORKBOAT REVIEW | 17

FINS FOILS AND AIR SUPPORT

8 A RIB fitted with fold away hydrofoil fins to reduce resistance

The success of the Sealegs amphibious craft has led to copies, some offering four wheels for better stability and other offering wheel structures that stow away with different systems. There is a market in the workboat sector for craft like this which can offer a viable means of personnel transfer out to contractor’s equipment moored offshore or for survey work.

A further development of the amphibious concept uses a pair of caterpillar tracks fitted under the boat for use when coming ashore for land transport. These units are lowered down

8 An experimental foil supported water taxi on the River Seine

18 | WORKBOAT REVIEW

under hydraulic power and provide good traction on softer beaches. When afloat the tracks fold up into the hull which adopts a more or less deep vee shape. Apart from the extra weight this system performs pretty well but so far its use has been in the leisure sector although there is potential in the workboat sector.

When you look at all of these alternative concepts for workboats and patrol boats there are always compromises that have to be considered. The air cushion of a hovercraft can offer advantages in terms of access to remote areas and transport over challenging terrain but these advantages have to be balanced against the higher costs and maintenance and it is the same for most of these advanced concepts. Of course there are compromises in nearly all powerboat designs and technology whether they use what might be termed exotic or conventional technology and this is where the skill of the designer comes in. Design has to be a considered balance between advanced technology, performance requirements and most of all, cost. What may work for the leisure sector may not be viable in the more hard-nosed workboat and patrol boat sectors where the operating hours can be considerable and where reliability is paramount. I think it is safe to say that the only true innovation that has been seen in these sectors of the market has been the RIB which probably now accounts for a considerable proportion of market, particularly for patrol boats. This development of the RIB shows that there is scope for new development but it will be a long time before any of the new concepts listed above make their way into the mainstream although the quest for a greener type of workboat may hasten the trend.

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8 The complex structure of a SWATH that makes them more expensive than a normal catamaran

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WORKBOAT REVIEW | 19

ENGINES

CHAPTER FOUR

ENGINES

Credit Cheetah Catamarans

responsive with a high power to weight ratio. Reliability is now taken for granted and it is rare to find a modern engine breaking down with any faults tending to be related to the auxiliary systems that provide the fuel, cooling and exhaust for the engine.

8 An outboard power police patrol catamaran

The past 50 years have seen some dramatic changes in work and patrol boat engines and it would be safe to say that it has been the development of compact and lightweight high speed diesel engines that has made the current fleet of fast patrol boats a viable proposition.

However the changes have taken place throughout the range of engines used in workboats and from outboards with tenuous reliability and smoky diesels of limited power and high weight we have now entered an era where all engines combine reliability with reduced fuel consumption and low emissions, a situation that has been directed largely by emission legislation.

The current outboards are powerful and reliable and now we are seeing diesel versions of outboards that have the ability to make a considerable change in work and patrol powering. In the smaller sizes up to around 500 hp the current marine diesels are light in weight and highly

RELIABILITY It is this change in engines that has had a considerable influence on both planing and displacement workboat design. As we said in the introduction reliability is of paramount importance for most work and patrol boat operations and it is the modern diesel that has played a significant part in these higher standards of reliability. This change has come about for two main reasons. Firstly there has been a much wider recognition that it was the engine systems, the systems that support the engine to keep it running such as the fuel and electrical systems, that were the cause of so much unreliability rather than the engine itself and secondly the switch from engines developed solely for marine use to engines that are based on automotive units where there was a strong accent on reliability and where lightweight was important and where there was large funding available for research and development to ensure this reliability. It is this combination of lightweight, reliability and low fuel consumption that has made the modern fast work and patrol boats viable and reliable.

FUELS At present most work and patrol boats use diesel as their fuel. Diesel is attractive because it is a safer fuel, it is much more readily available at marine refuelling points and in remote areas than petrol and it tends to be cheaper with some countries offering tax incentives in favour of using diesel. The fuel consumption of diesel engines tends to be better than and at least equivalent to petrol engine as well. We have seen petrol being used as a fuel for many smaller RIBs where diesel engines were not an option because of weight, space or cost and this applied to many boarding and rescue boats carried on board ships but the

8 A workboat engine room in a composite hullx. Far right: A diesel outboard on a small workboat

20 | WORKBOAT REVIEW

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ENGINES

advent of diesel outboards is changing that approach as well. Indeed many navies around the World now insist on diesel power for their boats in the interests of safety and that that has been a considerable incentive in the development of diesel outboards.

Virtually all marine engines on the market today are derived from automotive units, certainly in sizes up around 600 hp. From there upwards the engines tend to derive from diesels developed for earth moving equipment, trains or large trucks and even the 2000+hp marine diesels tend to come from a common base engine that has a wide variety of applications in other forms of transport and power generation. This helps to keep costs down, particularly development costs that can be very high on modern electronically controlled engines. The use of electronic control and its associated common rail injection systems has been a major factor in marine engine development and whilst it does improve fuel consumption and reduce emissions, the downside is that the engines are totally reliant of the electrical supply not only for starting but for running and control and so the electrical supply on work and patrol boats is now a vital factor in assessing reliability.

EMISSION STANDARDS The use of truck engines for marine requirements began around 40 years ago with companies like Volvo, MAN and Mercedes looking for alternative markets for their engines. In those days the marine sector was relatively free as regards the standards for engines. As emission standards started to emerge then it became more and more necessary to use these automotive engines which had been developed to meet the increasing demands of the higher standards. There was a spate of new small marine diesels that were based on car engines that started to transform the market and edge the petrol engine out as the power outputs of these small engines began to nearly match that of petrol engines.

The challenge for the engine manufacturers today has been to meet the increasing demands for reduced emission standards. These are set by the EPA in the US and by the EU in Europe whilst the international marine body IMO has set standards for shipping and other vessels. It is something of a confusing picture with slightly differing standards and different enforcement dates but the engine manufacturers know they can’t sell engines that don’t meet the prevailing international standards and even the future proposed ones and they have to aim to meet the highest standards amongst all of these regulators. We have passed from Tier1 and are currently on Tier 3 standards for the EPA requirements with Tier 4 waiting for the future. In the EU there are standards now reaching Stage V which are similar to the US EPA tier 4 whilst there is Tier 3 for the IMO based standards which relate mainly to ship engines but which are becoming applicable to most workboat engines now.

Whilst there are strong moves to harmonise all of the various standards so that there is one international level that engine manufacturers and installers have to meet which is why they tend to go for the most stringent knowing that they will conform to the others. So far the required emission standards have all been achieved by making the engines use the diesel fuel more efficiently. This was achieved firstly by introducing turbo-charging and inter-coolers to engines and then more recently introducing the common-rail engine which uses a more efficient very high pressure injection system that is controlled by sophisticated computer based systems that can make fuel injection and timing much more precise.

Most work and patrol boats in the sizes covered by this book will have engines that operate using normal pump diesel fuel. This is a low sulphur diesel and this fuel on its own will produce low emissions so that the engines using this fuel will meet the latest SOx emission requirements.

Things get more complex when trying to meet the latest low NOx emission requirements and this means that complex exhaust gas after treatment will be required. Now most engine manufacturers of marine engines the 130 kW mark have developed these exhaust gas treatment systems.

Not only do these exhaust gas systems add to the cost but they demand extra space in the engine compartment and of course add extra weight and complexity and also require the addition of specialised chemicals that have to be carried in tanks. This is a further part in the complication surrounding emission standards but operators should take comfort in the builders and engine manufacturers keeping abreast of the requirements. Most modern diesel engines require high quality clean fuel for the common rail fuel systems and this is where the operator has to play their part in reducing emissions and getting reliability.

8 4.5 Eden Rose Wave Piercer (Tidal Transit) Jan Moreno Patent

ELECTRONIC CONTROL Probably the most significant change in marine engine design that we have seen in recent years is the switch to electronic control. Again this has largely been in the interests of reducing the emissions but it has also led to a significant improvement in performance. The electronics come in the form of a compact computer attached to the engine and this can control the combustion process by varying the timing of the injection and the amount of fuel according to the load on the engine. With the use of the electronic control it is possible to fine tune the engine for its particular application, not only in the engine rating for continuous operation but also features such as the rate of acceleration when the throttle is opened and the torque characteristics of the engine so that to a large degree the engine can be tailored to

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8 Exhaust gas treatment system on a MTU diesel to reduce emissions

WORKBOAT REVIEW | 21

ENGINES

8 Tug engines now have to be compliant to IMO standards

8 Auxiliary systems in the engine room

the applications for which is being used. This is why you see so many different engine ratings applied to one engine in the manufacturer’s ranges. The electronic systems also allow for wide range of engine monitoring to be incorporated into the system so that the operator gets warning about any undue temperature or pressures on the engine that could point the way to failure. This area can be something of a minefield about who has actual control of the engine, with the manufacturers wanting to play it safe so that the engine shuts down or at least slows long before a failure might be imminent with the operator having little or no say in the matter except hopefully an alarm will have gone off to give warning of the impending change. These electronic systems are becoming highly sophisticated and they are being used on smaller and smaller engines so that today the electronic control is virtually the standard but they do beg the question about who is actually in control.

ALARMS On the matter of engine alarm systems it has now become the norm for an engine monitoring panel to be offered as an alternative to the individual analogue dials of the past. This has the advantage in that it offers much more information about what is going on with the engine including fuel consumption figures and a much wider range of alarms but in most cases when an alarm sounds the display does not offer much help, only showing what the alarm might be such as ‘low oil pressure’. It would be much more helpful if there could be some indication of what action to take to stop the alarm. Any fault with the engines on a work or patrol boat can have far reaching effects in terms of operational aspects so that you feel that the engine manufacturers should be giving the operator more information and help. These same systems also allow for remote engine monitoring from the shore and there could be a case for developing this interface to provide more and better support. On many boats that I have tested an alarm might sound and the operator simply switches it off until it

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sounds again. Sometime the alarms have become so commonplace that they have lost any urgency and the operator assumes he/she knows what the problem is from past experience and switches off. This sort of complacent attitude could become a source of trouble in the future as we are starting to assume that the engine monitoring system will take care of any problems and alarms can be ignored. Also there are so many factors that are being monitored both with the engine and propulsion but also with many other factors around the vessel that alarms systems have become very complex and if you add in the navigation alarms, the crew can become alarm overloaded.

ELECTRICAL SYSTEMS The increase in efficiency obtained with electronic control is a significant benefit but the downside is that the engine is now totally dependent on the boat’s electrical system to operate. Lose your electrics and you loose propulsion. I was brought up at a time when if anything electrical worked on a boat then that was a bonus and you did not rely on electrics but today the boat is not viable if the electrical system is not working. This has meant that work boat builders have had to raise their game considerably when it comes to installing the electrical system and nothing short of a 100% reliable system will do. Most boat builders and designers still install electrics as the one basic system so that a failure in one part could lead to a total failure and it would be nice to think about having back-up electrical systems for use in the event of the main system failing. At least have systems that can cope with a fault in one area by having the capability to be automatically switched to an alternative circuit to maintain the supply.

It is not just the main engine(s) that are dependent on the electrical system but these days we are also seeing ‘fly-by-wire’ systems that are used to control the steering, the throttles and the gears and if you add in all the auxiliary systems then you begin to realise that the whole boat is

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ENGINES

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almost entirely dependent of the electrical system so the requirement for a back-up system at least for the essentials should become apparent.

The modern marine engine is a very reliable piece of kit and I cannot remember the last time the engine itself actually broke even under the high stresses of very fast boat operations. What can cause problems with modern engines are the additions, the systems that supply the engine with fuel, the electrical supply, the cooling water and the exhaust.

The engine itself will have been thoroughly checked and tested during design and manufacture but these peripheral systems will have been designed as part of the boat design and will often be one-off systems particularly on an individually designed boat. This means that they will have had little or no testing in adverse conditions prior to installation. It only wants a wire to chafe against a sharp edge or a fuel pipe to vibrate and cause a leak or maybe a cooling water hose to perish and the engine will stop working, faults that even the most sophisticated electronic systems will not cure. Boat builders can rarely take the time or expense to put their boats through a long period of testing in adverse conditions prior to putting them on the market so when buying a new boat the design is to a degree going into the unknown. Boats are still virtually hand built these days, so much relies on the people doing the work and the levels of inspection and checking. This means that we still have some way to go to ensure the reliability of modern workboats which is one argument in selecting a boat with a proven track record when buying a new boat rather than going for a one-off design.

COOLING SYSTEMS The engine cooling system can be particularly vulnerable with a fault on the seawater cooling side possibly having major consequences. If there is a leak in these seawater circuits then the engine compartment starts to flood whilst the engine will not overheat immediately because it takes time for the fresh water circuits to react. Not only is the vessel flooding but the cooling water to the exhaust has stopped and the rubber sections if they are fitted could possibly catch fire. It is the sort of chain reaction event that could be caused by poor maintenance and inspection of the pipework and fittings. Because the engine is normally flexibly mounted the connecting pipe work and wiring also has to be flexible and this can be a source of weakness unless it is very well engineered. There is a case for installing the engines in separate compartments so that such a failure in one does not infect the other engine. One way to solve the requirement for seawater cooling for the engine is to fit a keel cooler where the closed circuit fresh water cooling system is cooled by means of a heat exchanger or keel cooler fitted outside the hull. No seawater comes into the vessel but that keel cooler could be vulnerable to debris impact or fouling that might reduce its efficiency.

EXHAUST TREATMENT As far as can be foreseen we have reached or are close to limit of what can be achieved by making the engine more efficient and with higher emission standards already being discussed and likely to be implemented soon, it seems likely that it will only be possible to meet these by introducing exhaust treatment systems which will be used to clean up the engine exhaust before it enters the atmosphere. Already the cost of diesel engines has increased considerably because of the increased complication to meet current emission standards but there has been a return in terms of the higher efficiency of the engine. Exhaust treatment systems will not add anything to the efficiency of the engine, indeed they may well reduce this efficiency and it will certainly raise the cost and increase the weight and size and space requirements of the engine so overall we are likely to see a reduction in performance with no corresponding return in efficiency. The increase in size and the engine space required will concern designers because it will mean that more space has to be allocated for the machinery. Some engine manufacturers, particularly those building the larger sizes of engine say, over 1000 hp, have developed systems in anticipation of the new regulations.

These can involve exhaust gas re-circulation or urea based systems as well as filters and the extra size and weight can be up to half that of the basic engine. In addition to extra cost and weight there will be an additional service requirement so the future might look cleaner but it will almost certainly be more expensive as far as engines are concerned. Currently the rules about these ‘cleaner’ engines only apply to those producing over 800 hp in US waters but they will also apply in the Baltic and North Sea so that most workboat requirements will be affected. See the comments in the section below about multiple engines.

ALTERNATIVE FUELS Using alternative fuels may be one way round the increasingly tight emission standards and here there are several possibilities. Hydrogen, methane, LNG and LPG have all been touted as potential boat fuels but here we are faced with something of a chicken and egg situation. Whilst there may be some supplies of these available for cars and trucks on land and ship bunker systems are being established, as far as is known there is nothing being done to make supplies available for boats. So no boat builder or owner is going to propose using these fuels until supplies

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8 Powerful outboard provide the power for this high speed patrol boat

Credit: FB Design

Already the cost of diesel engines has increased considerably because of the increased complication to meet current emission standards but there has been a return in terms of the higher efficiency of the engine

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infrastructure for supply and refuelling that will hinder progress with these alternative fuels. The technology is there but operators are less likely to invest in the new fuel technology until the refuelling infrastructure is in place and the same applies in reverse. It is a bit of a chicken and egg situation although increased costs can also be a factor. For the foreseeable future workboats using these alterative fuels are likely to be mainly harbour craft where fuelling infrastructure may be available.

8 The engine layout of a hybrid tug

become readily available. Liquid petroleum gas (LPG) is available in steel bottles and is used for gas cooking on many boats and has been used as a fuel for the main engine in some cases. It is certainly cheaper because of reduced taxes but it means handling heavy gas bottles for refuelling so its use has been restricted to a few small boats. Liquid natural gas (LNG) is being used on some ships as a means of reducing emissions but it entails giving over a considerable amount of on-board space to the gas tank which is likely to limit its use on boats. Whilst there are now LNG bunkering stations for shipping, as far as is known none are available for boats so this fuel is something of a non-starter at present but that is likely to change. Hydrogen comes into much the same category although again it is being used in a few cars and it could well be the fuel of choice for workboats as there are already some harbour craft using hydrogen as a fuel. Storing hydrogen on board still requires space and on the existing workboats the choice so far has been a bank of smaller pressure cylinders as opposed to one large pressure tank. Engine manufacturers are starting to offer engines that will run on these alternative fuels with MTU offering gas engines in smaller sizes and ABC offering hydrogen engines, all of them based on existing engines with different fuel systems.

The future may see changes but it is mainly the lack of

MULTIPLE ENGINES The marine industry has been very conservative when it comes to the number of engines installed in a boat. It used to be a single engine and because of the reliability of modern engines we are seeing many modern displacement boats returning to the use of just a single engine. This is probably the best and most economical solution as costs and design challenges start to increase when you switch to two engines. Twin engine installations are now the norm for planing patrol boats partly because having two engines can mean smaller propellers which tend to be better at higher speeds. With a more conventional inboard installation we might see a planing powerboat in larger sizes requiring perhaps 2000 to 3000 hp installed and when you get to this size of engine they have moved outside the sphere of the normal mass produced truck engine and into the realms of engines with a smaller market and which tend to be at least partly hand built rather than mass-produced.

This puts the costs up considerably and an alternative to get to the required level of installed power might be to have say, four smaller engines each on its own drive rather than the two more powerful engines. Not only could there be a potential saving in cost, there could be a saving in weight and also a saving in space requirements for the engines.

Four smaller engine spaced across the boat would occupy a shorter length of the hull than would be the case with larger engines so it might be possible to gain a metre or so of extra internal space. For workboats there is the added flexibility of the propulsion with it being possible to operate on just a couple of the engines when high speeds are not required. Many patrol boats in particular spend a lot of their time operating at loitering speeds but still require the possibility of high performance on tap and the three or four smaller engines offer considerable flexibility in operating

Credit: FB Design

8 Multiple outboard installations are now becoming commonplace

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scenarios and potential fuel saving. Then there is the possibility that the boat can remain operational and still maintain planing speeds with one engine out of action if there is a single engine failure. Some Gulf of Mexico fast supply boats have four engines, an installation that can also offer a shallower draft.

One incentive that might hasten a move towards multiple engine installations is the introduction of EPA Tier 4 emission standards in the US and matching standards in the EU. As things stand at present these emission standards will apply to engines of 800 hp and above so this leaves boats that require more than 1600 hp in a twin installation the option fitting three or more smaller engines to obtain the required power without having to have the complex and expensive compliant engines. Under IMO rules the higher emission standards apply to engines over 130 kW so that even with four engines of this size there would be limited power available for most workboat propulsion systems. Maybe we will see 6 or 8 engined boats but it seems likely that operators will bite the bullet and specify engines with the full exhaust gas treatment systems. This is becoming a complex area of legislation and of course if boats are seen to be evading the emission standards in this way then the regulations may refer to the total installation power rather than the rating of individual engines.

When considering a multiple engine installation it is important to consider whether gearboxes can be run with drive from the propeller rather than the engine. This is mainly a question of the gearbox lubrication with some oil pumps driven from the engine side of the gearbox and others from the propeller shaft side. It is important that the gearbox retains lubrication when it is driven from the propeller as might be the case when its connected engine is out of action.

DIESEL OUTBOARDS A step in this multiple engine direction might come with the modern diesel outboard motor. Apart from some boarding boats and tenders and small harbour craft, the use of outboard motors for work and patrol boats was in decline in many cases because of the safety aspects of using petrol as a fuel but also because of fuel availability and higher fuel costs. The petrol outboard is cheap and because it is a simple bolt on engine unit it becomes feasible to carry a spare engine in case of engine problems. This can be a big bonus where a ship is only on charter or viable when it has a working tender or perhaps the boat is operating in remote areas where service help may not be close at hand.

Another bonus with using outboards is that the engines have their propulsion system incorporated into the unit which means that both engine and its drive system are fully tested as a unit and thus offer the potential of a high level of reliability. The modern petrol outboard is now available in powers up to 400 hp or more so that it can potentially be used as a power units for quite large craft if several units are installed on the transom strengthening the case for multiple engine installations.

The outboard motor started life as a very simple concept that could be clamped onto the transom of a boat to provide portable power. This type of outboard can still be found, although it is rarely used for workboats except in

very small sizes. The simplicity is enhanced with hand starting so no external electrical supply is required. Hand starting and transom clamping is practical up to about 50 hp but above that the outboard loses its portability and becomes a fixture bolted onto the transom for security.

We have mentioned that the use of patrol for work and patrol boat applications is in decline and there have been calls for a practical diesel outboard.

However the challenge of connecting a compact and lightweight diesel engine with adequate power to a lower unit that can handle the higher power and torque requirements has been a challenge. For years the Yanmar diesel outboard was the yardstick in this sector but its relatively low power at 35hp was not enough for most planing boats and as higher emission standards came into force production was stopped. A number of manufacturers tried to step into the gap with the majors such as OMC and Mercury producing adapted versions of their petrol outboards that could operate on diesel fuel. These were still spark ignited engines and they tended to be rather rough running, challenging to start and not particularly emission free although they provided a viable option. Then several small manufacturers tried adapting small automotive diesels to act as the power units for outboards but it was the high torque of the diesel that was the challenge, getting the power and toque of the diesel to the propeller.

Now we are seeing solutions for the diesel outboard being developed and at the time of writing there are several diesel outboards on the market. The smaller is the Neander Shark which is an innovative design with twin crankshafts that produces 55hp, a conservative power output that is likely to be upgraded. Neander is now marketed by diesel engine manufacturer Yanmar which offers worldwide servicing and a twin installation is likely to be adequate power for many RIBs and workboats as well as for displacement boats. The main attraction here is the worldwide servicing offered by Yanmar and these outboards have found a ready market in the fish farm sector that tends to operate their boats in remote areas where only diesel fuel is available.

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8 Compact diesel installation in a narrow high speed hull Inset: Petrol outboards converted to operate on diesel fuel

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Also coming onto the market and likely to be available at the time of publication is the Cox diesel outboard where they worked on the development of what is claimed to be the highest power density diesel engine

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For higher power outputs the Oxe diesel outboard is currently offering outboards with powers up to 200 hp and by the time of publication this is will be increased to 300 hp with smaller diesel outboards also being added to the range. These outboards use a compact high output automotive diesel engine with a horizontal crankshaft that is connected to a very innovative propulsion system that is probably one of the most significant changes to outboard design for many years. The drive from the engine is first taken to a compact gearbox mounted below the engine by means of a high capacity flexible drive belt. From the gearbox a second flexible drive belt takes the power down to the horizontal shaft of the propeller drive. In this lower section the toothed belt is guided by rollers so that the up and down paths of the belt are close together to allow a slim leg for the outboard and the lower drive roller is compact to create a slim lower unit. This drive system removes the need for the long vertical shaft and lower gears that in the past have tended to restrict the possible torque that could be handled by a diesel powered outboard.

Also coming onto the market and likely to be available at the time of publication is the Cox diesel outboard where they worked on the development of what is claimed to be the highest power density diesel engine. This V8 diesel will be rated at 300 hp and it is good to see that worldwide servicing has been established before bringing the engine to the market.

The handicap of both this engine and the other diesel outboards is their price. This is around double that of an equivalent petrol unit for the same power and they are also heavier but against this you get much improved fuel economy, a safer and more readily available fuel and hopefully an engine that will have a longer life. These factors suggest that the use of the diesel outboard will be restricted to mainly commercial and military users where high operating hours can justify the higher capital costs because of the fuel savings and for tenders of craft carried on board military ships where petrol fuel is not allowed. As production rises the cost of these diesel outboards is likely 8 The powerful Oxe diesel opens up new applications for workboats

to come down and looking ahead it is not difficult to see them being used more and more in the work and patrol boats sectors and the workboat sector may follow the lead of the leisure sector where multiple outboard installations of three or four units are used to power significant sized craft.

This would offer a significant level of redundancy as well as more space within the boat.

A different approach to semi-portable diesel power units comes in the form of the S30-OB developed by the Japanese company Hyundai Seasall. This new ‘outboard features many of the advantages of an outboard motor and combines this with the rugged simplicity of a tried and tested conventional drive system. This new diesel unit is powered by Hyundai’s 270 hp diesel engine but it is the way this power is transmitted to the propeller that is new.

The engine is close coupled to a drop-down reverse gearbox that not only lowers the drive shaft below the engine but also reverses its direction. This allows the propeller shaft to exit below the engine at a shallow angle to produce the thrust.

The whole unit is housed in a casing that it bolted to the transom with the casing allowed to hinge vertically under the control of two hydraulic rams. This allows the trim to be adjusted when underway and also allows the whole unit to be tilted out of the water. Rather than have the unit swivel for steering like a conventional outboard, the steering is by means of a rudder mounted behind the propeller in the conventional way with the actuating mechanism inside the engine housing. A narrow strip under the propeller helps to protect it from ropes and debris.

With a power output of 270 hp this new diesel ‘outboard challenges the existing diesel outboards on the market and there are plans to produce a unit with a higher power of 360 hp that will make it the most powerful diesel ‘outboard’ on the market. A smaller 140 hp unit is also planned to offer a range to meet many workboat requirements. An option with the unit is to add a side thruster attachment and a hydraulic power take-off is also possible.

This new outboard system was originally developed for use by South Korean fishing boats where it is already in use. It is now planned to market it worldwide where it is likely to be attractive to workboat and fishing boat operators where diesel fuel and rugged reliable performance rather than high speed are the users’ main criteria. A similar type of unit was developed in the US but instead of a propeller the drive was connected to a water jet but this concept never became commercially viable.

Bolted to the transom, these diesel outboards offer all the advantages of a compact and semi-portable installation that can operate on diesel fuel and where a faulty engine can be quickly replaced by a spare, potentially reducing downtime. It could be a transformational time in work and patrol boat design as it leaves more working space within the boat and the safety of diesel as a fuel. Because they are largely based on automotive derived engines they can meet the current emission standards although they may have difficulty if these standards are raised in a future where higher emission standards may require external exhaust cleaners.

ENGINE SELECTION At the end of the day the engines selected for use in work and patrol boats are likely to be selected by several factors.

One will be the engines in use in current boats in a fleet to ensure compatibility and common spares which can be important to fleet operators. Similar to this will be the

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HULL DESIGN

8 A high speed diesel adapted to operate on gas on the test bed

availability of local service agents who can quickly fix problems and supply spares in order to keep the boat operational. However at the end of the day it may well be finance that governs the choice of engine with engine manufacturers often offering attractive finance packages to gain entry to a market or to outfit a prototype design in the hope that future purchasers will adopt the same engine.

The designer of the boat may also have his or her say with perhaps the weight or size of the engine being critical to the design. It is a complex market with many factors affecting the selection of engines Engines for work and patrol boats have changed dramatically over the past few years and the changes have not always been to the benefit of the user. Costs have gone

up but perhaps more worrying now is the almost total reliance on the electrical system for the boat to remain operational. This follows the trend in cars and trucks but if these vehicles stop, then help can be readily available, If the engines of a boat stops at sea you are in a much more high risk and vulnerable situation which is why multiple engines installation may become more attractive and I am concerned that we are entering a time when the boats have become more reliable but at the same time if something does go wrong then the crew might be helpless to fix the problem because of the high level of technology involved.

There are plenty of options out there to find the optimum solution for the particular application in what is becoming a fast changing market.

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PROPULSION: THE KEY TO PERFORMANCE

CHAPTER FIVE

PROPULSION THE KEY TO PERFORMANCE more complex in the interests of efficiency some might argue that this complexity reduces the reliability. Many of the new developments are focussed on the requirements of the leisure sector where the running hours per year might be less that a 100 compared with those of a workboat which can be measured in 1000’s and where reliability is paramount.

8 An azimuthing drive unit with a pulling propeller

The engines in a work or patrol boat supply the power but that power has to be transmitted to the water in terms of thrust to get the boat moving. It is the propulsion system that largely dictates the performance of the boat as well as the handling and manoeuvrability so it is a key part of any boat. Efficient propulsion systems will also reduce the emissions and of course reduce the fuel consumption so that for a work or patrol boat that is in constant use it can assume vital importance and reliability also becomes an important factor.

In the past the shaft and propeller systems were the standard fitted to nearly every boat but today there is a wide variety of alternative propulsion systems allowing the propulsion to be largely tailored to the work that the boat has to do. Of course many of these still use the propeller but it is in the way that the propeller is connected to the engine that can vary and whilst propulsion systems have become

DRAFT CONSIDERATIONS Many workboats such as tugs and fishing boats are based on displacement hulls and here the propulsion system has to be designed to generate high thrust at low speed. Here a lot will depend on the size of the aperture available to house the propeller and in turn that will depend on draft. A large slower turning propeller is the best solution for generating towing thrust but we are seeing fewer and fewer boats with the deep draft hulls of old and so a different approach is needed with the propeller surrounded by a variety of thrust enhancing features such as nozzles, fins and vanes. Obviously a clean water flow around the propeller helps its efficiency and to avoid interference with this water flow minimum clearances are specified for the aperture in which the propeller operates. The usual figure for propeller clearances is 1/5th of the diameter of the propeller but this is often narrowed down in the interests of compact design requirements. On twin screw displacement boats there is more freedom because the propellers are then located on either side of the skeg and the only clearance required is between the propeller and the bottom of the hull but again this should be as generous as possible for efficiency but the shaft angle is also important.

The draft can be an important factor on many workboats in order to reduce operating restrictions and at the same time for a propeller to be efficient the shaft angle should be horizontal as possible. This has lead to the current trend of propellers being installed in semi-tunnels which raise the height of the propeller in relation to the hull and allows a more horizontal shaft. This is particularly the case with a twin screw installation and whilst it works with displacement hulls it is now a feature of many planing hulls which has many benefits. Amongst them is the reduction in

8 A trimmable surface drive unit for high speeds Far right: A water jet propulsion unit with the distinct reversing system the deflects the water flow forward

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PROPULSION: THE KEY TO PERFORMANCE

8 Triple surface drive propellers on a high speed vessel

the draft as well as the reduced shaft angle but also, when combined with a central skeg it can allow for a degree of propeller protection in the event of grounding or hitting debris. A twin screw installation will normally require support for the shaft outside the hull and these P or A brackets are in the water flow going to the propeller so that they will disturb this flow to a degree. You have to accept that no propeller installation is going to be perfect and it is up to the designers to mitigate the effects of the water flow interference as much as possible.

PROPELLER OPTIMISATION It is only in these days where the focus is much more on fuel economy that the efficiency of the propeller on displacement hulls has been really considered. Much more time will normally be spent on optimising the design of the propeller itself and this is a highly specialised job because there are so many variables involved. Computational Fluid Dynamics allow propeller design to be computer analysed which is both faster and less expensive that tank testing.

The speed of turning of the propeller is one factor, and then there are the number and shape of the blades, the diameter of the propeller and its pitch, the angle of the blades that act like a screw cutting its way through the water. All of these factors have a bearing on the efficiency of the propeller and this is a job for the specialist. Once fitted, most of these factors cannot be changed short of fitting a new propeller and this is one argument in choosing a proven work or patrol boat design because the propeller trials will have been optimised on the prototype. Most good propeller makers will get close to the optimum when asked to design a propeller for a specific boat but fine tuning the propeller can be an expensive and time consuming job that can probably only be justified when a run of production boats is involved. It is much easier with outboards and stern drives where the diameter is usually fixed and standard replacement propellers are normally available off the shelf with varying pitches, blade numbers, blade shapes and even varying materials.

8 A comparison between a surface propeller (left) and a conventional propeller (right)

NOZZLES Nozzle systems, particularly for displacement hulls, can improve the thrust efficiency and there is a wide variety on offer, with the Kort nozzle still the main one. The aerofoil cross section of the nozzle in cross section helps to focus the water flow through the propeller to give the propeller a more stable environment to operate in but nozzles can be both fixed and steerable, the latter acting both to increase the efficiency of the propeller as well as acting as the rudder.

Now we are seeing some nozzle systems that have been developed for higher performance craft and most of these can be effective at speeds up to say, 25 knots, but at higher speeds the increased frictional resistance of the nozzle has to be balanced against the increase in propeller efficiency.

PLANING BOAT PROPULSION These same comments about propellers apply to planing boats of course and here the choice of propeller can be more critical. Not only do you want to maximise the top speed but you also want a propeller that can produce good thrust at lower speeds to get the boat onto the plane quickly and to provide economical performance at the cruising speed rather than perhaps optimising the top speed, although top speed is always an important sales factor. With planing hulls there are more options for the propulsions systems available although the conventional shaft and propeller is still a favourite for many designers

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WORKBOAT REVIEW | 29

PROPULSION: THE KEY TO PERFORMANCE

8 The propellers and rudder of a Trimax Surface Drive. Centre: A Dutch RIB lifeboat that relies on water let propulsion for working in shallow waters

and builders perhaps because it minimises the number and complexity of the moving parts underwater and it is well proven for reliability. The propulsion system on planing boats becomes more complex because the engine location can affect the centre of gravity and this can entail using short connecting shafts between the engine and the stern shaft. Again the shaft angle is important and this has to be considered along with the location of the engine and its effect on the centre of gravity.

When internal space inside the hull is important then a common arrangement that allows the engine to be located fairly well aft is to have the drive at the front end of the engine where the shaft line is then dropped down by a reverse/reduction vee drive gearbox that has the propeller shaft emerging at its lower part with the shaft running back under the engine. This can reduce the shaft angle and still keep the engine weight and space requirements well aft.

This question of shaft angle is important to propulsion efficiency and this can be judged by the fact that both outboards and stern drive legs have a trim function that allows their shaft angle to be adjusted when underway.

At rest the shaft angle is horizontal and as the boat rises onto the plane and the trim changes to a bow up position, the trim adjustment allows the shaft line to be maintained as near to horizontal when the trim of the boat changes. It is factors like this that make outboards and stern drives a practical alternative to shaft drive for planing boats and they probably offer greater efficiency despite the added complication and the power losses of the drive shaft configuration where it has to have bevel gears to get the drive to the propeller and as we have seen in the previous chapter outboards can also offer other significant advantages.

PROPELLERS With planing hulls the propeller(s) are operating at a more critical level and the shape of the blades tends to be more important to avoid cavitation problems. Cavitation on a propeller is the formation of tiny bubbles on areas of the blade surface that reduce the ‘bite’ of the propeller in the water and reduce the efficiency of the propeller. It tends to occur initially at the blade tips and can actually cause erosion of the metal of the blade but with modern design and a clearer understanding of the causes, propeller cavitation in now largely under control and good propeller

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design allows these fully submerged propellers to be effective up to speeds of around 40 knots which covers the vast majority of production planing hulls. Modern blade shape has changed quite considerable and we are seeing quite highly skewed blades on larger hulls where the tip of one blade overlaps the blade area of the adjacent blades.

Other blade concepts include the rounded blade tip and the straight edge to the trailing side of the blade. There appears to be a constant refinement of propeller blade design and the ability to now test propellers in test tanks has gone a long way to refining propeller design. An interesting propeller development was to have a raised ridge along the trailing edge of the blade to help deflect the water cleanly away from the blade and trials showed that is could lead to greater efficiency.

Another factor in propeller design is the thickness of the blades. As propellers are required to transmit more and more power from the engine to the water as thrust the stresses on the blades have grown higher and so the blades have had to be increased in thickness to ensure the have adequate strength. Materials have also changed and the traditional bronze for propellers is now often replaced with high tensile stainless steel. A new solution here is the advent of 3-D printed propellers. The first ones were made from a durable plastic which is quite easy to handle for 3-D printing but now the techniques of 3-D printing for metals have been refined so the first 3-D printed metal propellers are under trial. Composite propellers have also been used as a replacement for metal and again they have worked well but have not proved a commercial success so far. The number of blades on the propeller is also changing and whereas three blades was the standard we are 8 Deck mounted now seeing four and even five bladed engines coupled to propellers. An odd number of blades azimuthing drives appears to be preferred which is claimed to reduce vibration.

SURFACE PIERCING PROPULSION Problems with cavitation and the requirement for propellers that could operate at higher speeds led to the development of the surface piercing propeller. It has long been recognised that fully submerged

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PROPULSION: THE KEY TO PERFORMANCE

propellers could be operated well beyond their theoretical limits when cavitation was the limiting factor. Supercavitating propellers were developed that could operate effectively well into the cavitation zone when higher speeds were required. With surface propellers this was taken one stage further by using propellers where only the bottom blades of the propeller were in the water doing the work and the top blades were in the air, or at lest in the spray zone at the water surface. The theory here was that it was the bottom blades of a propeller that were doing most of the work anyway because the flow of water to the top blades was affected by the shaft and its support brackets so why not take these top blades out of the water and let the bottom blades do all the work?

It required a considerable re-think of propeller design because now cavitation was not a problem and the blade shape and style could be optimised for power transmission.

At the same time the stresses on the propeller were dramatically increased because you can imagine the stress when a propeller blade that is transmitting several hundred horsepower when that blade is in the water and then transmitting no power at all when the blade is in the air and this load cycle happens perhaps 2000 times a minute.

Making the propeller strong enough was the main challenge faced by the propeller designers and not only was forged stainless steel used but the cross section of the blade particularly near the hub was much thicker. Even then there was the fatigue of the constant loading and unloading of the blade to overcome and shedding a propeller blade was a not uncommon problem on performance boats. The propellers for surface drives tend to be more aggressive looking with very sharp leading edges and sharp cut off on the trailing edge, often with a lip to accelerate the water away from the blade at the final moment. It is normal to find surface propellers with an odd number of blades, perhaps three or five as this reduces the vibration that can be associated with surface drives. With an even number of blades one will be coming out of the water as another enters and

this is what can cause the vibration but with an odd number of blades there is a more even balance of the loadings.

There was also the problem of getting the boat onto the plane. At slow speeds the fixed surface propeller is fully immersed and so when power is applied, it struggles to absorb this power because all of the blades of the propeller are in the water and cannot break free so the propeller is very overloaded and the engine cannot turn fast enough for the turbochargers to start working so there is reduced power to get the boat moving. These days with fixed surface propeller installations that are integrated into the hull it is usually the engine exhaust that is used to ventilate the propeller but this needs care to stop the water running back up the exhaust when going astern. With articulated surface drives such as the Arneson you actually lift the propeller partly out of the water to reduce the loading and so get it moving and allowing the engine to increase rpm as the boat comes onto the plane.

8 5-bladed surface drive propellers with rudder steering that reduces the chance of a spin-out

SURFACE DRIVES Modern day surface drive systems are integrated units which in most cases bolt onto the transom. There are quite a few on the market today but the pioneer was the Arneson Drive which was a complex piece of engineering that introduced a universal joint into the shaft line that allowing the final section of the shaft to be angled both vertically and horizontally with control of the movement by hydraulic rams. The vertical movement was to lift the propeller from it’s fully immersed harbour manoeuvring mode so that the boat would get onto the plane and let the propeller operate in fully surface piercing mode with the hub at the water surface level. The horizontal movement allowed the propeller thrust to be used for steering thus taking away the need for a rudder. Today there have been several look-alike systems on the market with the SDS from France Helice probably being the best known. This has all the controls and hydraulics inside the boat rather than exposed to the elements like on the Arneson.

The Trimax Drive is a surface drive with a subtle difference. There is a universal joint in the drive shaft and this allowed the shaft angle to be optimised for performance but once optimised the shaft was then locked in place and rudders were used for steering. It required a modified hull design and in later versions has special flaps added to assist planing but it proved to be a highly efficient and reliable

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WORKBOAT REVIEW | 31

PROPULSION: THE KEY TO PERFORMANCE

You can get much the same excellent manoeuvrability with conventional propulsion combined with bow and stern thrusters that enable the boat to be moved very precisely even is strong winds and tides

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find the right propeller sizes for the job. Now we are seeing contra-rotation propellers used on stern drives and on many of the new pod drive systems and integrated into these systems they offer a viable and efficient alternative. To get the two propellers running in opposite direction is a simple matter of additional gearing and an extra shaft of course and it is argued that the benefits outweigh this extra complication. Contra-rotating propellers on fixed shaft systems are also under development.

8 Considerable modifications are required to the engines on a self-righting vessel

surface drive system and it took the delicate task of adjusting the height of the drive shaft out of the hands of the driver thus reducing the driver’s input and workload.

There is no doubt that the surface drive systems are more efficient when speeds of over say 40 knots are required but because of this and their added complication they are only a small part of the fast boat propulsion market and only viable for speeds over about 40 knots.

CP AND CONTRA-ROTATING PROPELLERS Controllable pitch propellers where the pitch of the propeller blades can be varied when under way have been used for a long time but mainly for specialised applications and only on displacement hulls. The operating mechanism to vary the blade angle in mainly inside the propeller hub so a fairly large hub is required which reduces the efficiency and there can never be the same strength in the unit as there would be with a solid cast propeller. The advantages are that the propeller can be optimised for the load and speed when these vary considerably in the operational scenario whilst allowing the engine to run at a constant and perhaps more efficient speed. CP propellers for planing boats have been developed by Servoprop and have a good operational record, again on boats where the operational scenario varies considerably such as on load carrying wind farm vessels. Here there has to be a balance between higher efficiency against higher costs and complication.

Contra-rotating propellers are another option and there is no doubt that they improve the propulsion efficiency, possibly by as much as 10% but again there is the added complication and cost of the system and the challenge to

8 A propeller being constructed using 3-D metal printing

32 | WORKBOAT REVIEW

POD DRIVES Pod drives are gaining ground as a viable propulsion system for planing powerboats and the Volvo Penta IPS Drive has led the way here. These IPS Drives fit under the hull rather than on the transom so the propulsion point is moved forward under the hull and the propellers are at the forward end of the drive. This has led to hull design complications and these days Volvo Penta has hull design specifications when these drives are fitted. Other pod drives such as the Zeus are transom mounted and drive in the conventional way with the CP propellers aft. The advantage of these pod drives is the exceptional manoeuvrability because they can rotate through 360° and direct the thrust in any direction. This makes them perfect for joystick control where you simply point the joystick in the direction you want the boat to move and the computer makes the necessary settings and away you go. You can get much the same excellent manoeuvrability with conventional propulsion combined with bow and stern thrusters that enable the boat to be moved very precisely even is strong winds and tides. These joystick controls are becoming very sophisticated with the autopilot and the GPS linked in so that you can maintain a set heading and even a set position using the GPS as a position reference. This is a form of dynamic positioning that can be used on small work and patrol boats which could be effective for some types of operation. It can take quite a lot of faith in the electronic control systems when using these joystick controls in critical manoeuvring situations but then electronics tend to control everything on board these days. Now we have automatic docking systems where sensors can detect obstacles and can manoeuvre the boat into a berth alongside, the computer doing all the work for you except attaching the lines. The days of the automatic workboat are not far off!

Larger pod drive systems are coming onto the market some capable of handling power outputs of over 1000 hp.

Some of these fit under the hull and some are transom mounted and one unit produced by Rolls Royce uses composite mouldings in its construction marking a departure from convention. These pod drives for fast boats match the use of similar types of drive systems found on modern tugs and many construction craft. These azimuthing pod drives for displacement vessels are usually fitted with a nozzle and can give tugs exceptional manoeuvrability. Whilst the common arrangement is to have two of these thrusters

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PROPULSION: THE KEY TO PERFORMANCE

installed aft having a third one forward is another other possibility and tugs with thrusters can manoeuvre sideways ways as well as in the more conventional way.

WATERJETS Another and very versatile option for propulsion ion is the water jet. First developed nearly 100 years ago go water jet propulsion has been refined over the years and nd makes an attractive option for many workboats particularly ularly on larger RIBs and on rescue craft. Its attraction here is safety because there are no exposed moving parts but the water jet is never quite as efficient as a well designed propeller system and the relatively high cost and the increased weight and complication are probably ably what has prevented wider use. The increased weight mainly comes about because the weight of the water contained ained inside the jet tunnel has to be added to the weight of the he boat itself when it comes to propulsion calculations.

Where the water jet scores is in its ability to cope with a wide range of loadings so it works well on boats oats where the weight of the boat or its operational requirements ments vary considerably. It is also viable in waters where e floating debris might be encountered and where there can be a considerable variation in the loading of the workboat in its operating scenario. The standard water jet has as the engine running in the same direction and in gear at all times when it is in use and steering is accomplished by moving oving the steering nozzle to direct the thrust. For reverse se a ‘bucket’ or deflector is lowered over the exiting water thatt serves to t re-direct it forward under the boat and you can engage reverse at full throttle with quite dramatic results as the bow of the boat dips considerably and the boat comes to a rapid halt. Water jets are favoured by vessels that have to beach such as landing craft because the reverse thrust effectively lifts the stern as the boat backs off the beach. A problem with water jets is that fouling can occur in the jet tunnel if the boat is left idle in the water for some time. This should not be a major problem roblem for most workboat operations where boats are in constant use but suggests why the leisure sector ector has been reluctant to adopt water jet propulsion.

Manoeuvring with water jets is very impressive once you understand what you a trying to do. It is the reverse that tends ends to confuse most people and more so when you have twin jets. Like the pods and conventional systems most jet manufacturers have ave developed joystick control systemss that do most of the thinking for you and allow you to park the boat into tight spaces. Some outboard oard manufacturers offer a water jet version ersion of their outboards. This is achieved by removing moving the lower unit and replacing it with a pump that has a simple reverse bucket over the he nozzle.

You loose quite a bit of efficiency with this

8 A portable p combined engine and propulsion package that can be a packa simple bolt on system

solution but it can be a useful adaptation for perhaps a rescue boat or some workboats.

STEERING SYSTEMS Closely allied to propulsion system is the steering and in some cases the propulsion is used for the steering. This applied to water jets and to some types of surface drives and of course to outboards, stern drives and pod drives. Using the thrust for steering is extremely effective but it can be quite powerful as well.

The engine has to be in gear for any steering effect ff t and d on hi high h speed db boats t using i such h dynamic steering can lead to a more uncomfortable ride because there is no subtlety in the steering effect so course keeping may not be subtle with the boat tilting even at small course alternations. It can also lead to a spin out where the boat suddenly turns end for end when turning too rapidly rapidly. Rudder steering is much more gentle and perh perhaps its main disadvantage these days is that it is more difficult to integrate into joystick control sy systems.

The pro propulsion system is the key to perfor performance for most work and patrol boats and th there are so many alternative systems now on the market that finding the right syste system can be challenging. This is probably why the majority of work and patrol boats and certainly the major boat builders and most of the smaller ones tend to stick to the tried and an test systems of shafts and propellers.

Here I have mentioned most of the basic sys systems but amongst those there are a lar large number of alternative systems dev developed by people who are looking for grea great efficiency but rarely greater simplicity and in boats bo in general and fast boats and workboats in particular keeping it simple is the solution that usually pays off in the long run.

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8 An example of the increasing complexity of modern propulsion systems

WORKBOAT REVIEW | 33

THE CONTROLS

CHAPTER SIX

THE CONTROLS 8 A control head using electric switching for gearbox control

The controls on a workboat represent the interface between the helmsman and the vessel and so play a vital part in the effective operation of the vessel. There was a time when the controls were just the steering wheel and the throttles but with the advent of electronic systems, joysticks and a variety of control surfaces, things have changed considerably. These days the helmsman can have many alternative ways to control his/her craft and to optimise the performance and in specifying a new vessel it is important to have an understanding of these factors.

This is particularly the case with faster planing boats where so much of the performance and comfort is in the hands of the person driving the boat. For any work or patrol boat it is also important to consider the ergonomics because the helmsman can spend long periods at the helm.

For heavy duty displacement workboats it is likely that the only controls for driving the boat will be the steering wheel and the gear/throttle lever/levers. However more and more of this type of craft, particularly tugs, are being fitted with a type of pod propulsion and this offers up the possibility to operate the vessel through a joystick control systems. On these displacement craft there may also be the controls of the deck machinery in the wheelhouse, freeing up the crew working on deck for other duties.

We will look at crew comfort in a later chapter but here we are looking at the actual controls and how to use them to best advantage. First then is the steering where tradition dictates a vertical wheel with the helmsman standing at the wheel. Today the helmsman is almost always seated at the helm with the controls within easy reach. With the helmsman seated the main options for steering are a vertical wheel, an angled wheel rather like that found in a truck and no wheel at all with steering done by a tiller.

Assuming that power steering is installed as will be almost all cases then the shallow angled wheel is probably the best solution because it allows the helmsman knees to fit under the wheel and leaving the wheel easy to operate without reaching out. Most steering wheels can be angled to suit so that a comfortable angle can be found to operate the wheel within a limited range.

Tiller steering is being increasingly used and it will operate through a ‘fly-by-wire’ system. Tiller steering is fitted on the basis that it will be mainly used at slow speed when sensitive operation of the steering is not required with the autopilot taking over when out at sea. I am not a particular fan of tiller steering and I do find the absence of a steering wheel disconcerting but we are now seeing lifeboats being fitted with just tiller steering so there must be some benefit. When assessing the type of steering,

8 Good throttle control is vital to the effective operation of fast boats like this

34 | WORKBOAT REVIEW

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THE CONTROLS

much will depend on the type of boat and its operations with a displacement workboat probably benefiting from tiller steering whilst a fast patrol boat needs very sensitive steering so only small movements of the wheel are required at high speed. A fast boat with a deep vee hull will heel over when the steering is turned which will give a harsher ride in waves so the steering should be sensitive enough so that control can be achieved by just very small movements of the steering wheel. It can be a fine balance and a good solution would be to have steering that offers several turns lock to lock at high speed but which can be quickly operated to hard over for harbour manoeuvring. It should be possible to achieve this with modern fly by wire systems or by a combination of wheel and tiller steering.

A bit will depend of whether power steering is fitted which will make the steering light and easy to use and with that steering a more vertical wheel could be OK. Many prefer the steering to be a bit stiff so that you do not move the wheel inadvertently due to the movement of the boat and in the case of a more horizontal wheel angle the position allows you to pull on the rim to turn the wheel. This more horizontal wheel would be my choice but it does mean that you need to tuck your knees in under the wheel to operate it easily.

This question of steering ratio can be important with a propulsion system where the thrust from the propeller is used for steering control as with outboard and stern drives.

Here the steering is only active when a gear is engaged and so you want to be able to quickly set the steering angle before engaging gear when manoeuvring in tight spaces.

What might be the ideal solution would be steering where the steering ratio automatically changes according to the speed of the boat but perhaps that is a complication too far although some high value cars have such steering systems.

Then there is the question of feed back in the steering so that when you are turning the steering wheel you get the feeling of holding the wheel over rather than the dead feel on any steering systems. Tradition still plays a large part in the type of steering used on many work and patrol boats but as electronics are used more and more in modern steering systems the possibility of tailoring the steering to the requirements of a particular boat or operation expand and we will see change in the future.

As part of the steering system on work and patrol boats the autopilot should be considered an essential component.

Apart from releasing the crew from concentrating on following a compass course when on a long run offshore there are many benefits from using the autopilot. Manual steering following a compass course will be erratic at best and with the autopilot keeping the vessel on course to

8 Diagram showing the operation range from neutral before the gears are engaged

within a couple of degrees of less there can be a useful saving in the distance covered leading to savings in fuel and time. Added to this is the release of a crew member from focussing on the steering so it should be possible to keep a more effective lookout and navigation operation but there can also be more subtle benefits.

With a fast boat based on a deep vee hull the boat will heel over when the steering is turned. When operating in waves this heeling to take away some of the benefits of the deep vee cushioning because the boat will be landing unevenly in the waves so impacts will increase. The greatly reduced steering corrections when running on autopilot should lead to a more comfortable ride offshore. The benefits of the autopilot extend to inshore and harbour operations as well with the unit holding a set course allowing the navigator to concentre of finding the way ahead and on collision avoidance. To get the maximum benefits it is important to use a quality autopilot and one where the control of the course is a rotary knob rather than push buttons. This rotary knob then effectively becomes the steering wheel allowing quick and sensitive course control.

If joystick control is fitted then it is common to find the autopilot integrated into the system with a push button in the top of the joystick engaging the autopilot to maintain a set heading. Another factor to consider when selecting the autopilot is the disconnect system. This is usually a push bottom on the control panel but this should be clearly marked and readily accessible and be clear both day and night so that manual control can be quickly engaged perhaps in the event of sighting debris ahead.

Rather than trying to correct each and every alteration of course that the boat may make as it impacts with waves it is much better to let the boat have its head and most of the time it will come back on or near the course of its own accord without you having to make any steering corrections. Even when it does wander more than you would like, bring it back on course by just small movements 8 Seating and controls need to be closely integrated for effective control. Far left: Effective steering and throttle controls of a slower workboat

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WORKBOAT REVIEW | 35

THE CONTROLS

8 A bow ballast tank system that can be used to adjust the trim

of the wheel and you will get a much better ride in waves.

That light touch on the wheel will pay off in a more comfortable ride.

It is not easy to adapt and use this lighter touch on the steering because the natural reaction is to grip the wheel tightly in lively seas in order to feel in control. You do need to be sitting or standing securely if you are going to use the light touch and again it is a natural reaction to grip the wheel hard to help balance against the movement of the boat even when you are secure. Sometime I find myself having to actually force my hands to relax on the steering wheel but the benefits quickly become clear.

On most powerboats the steering ratio, i.e. the number of turns of the wheel from lock to lock, has to be a compromise. You want a quick steering response at low speeds when you are manoeuvring in harbour and yet out in the open sea you want a much slower response on the wheel so that you can achieve that delicate response you need to avoid un-necessary heeling. It would be great to be able to switch ratios but this is rarely possible so the steering response has to be a compromise. One way to achieve the ideal is to switch from wheel steering at sea to tiller steering in harbour and that can be done with many modern systems.

Steering is such an important part of patrol boat control but little attention seems to be paid to getting it right. “This is how we have always done it” is the mantra heard so often, but in the open sea I would think steering with 3 or 4 turns lock to lock would be about right. The other factor to make life easier and the control much better is to have an adjustable steering wheel where the angle of the wheel can be altered to make it more comfortable to use. You will struggle to get the angle right when sitting at the helm in harbour and the ability to vary the angle of the wheel can help the control considerably.

Credit FB Design:

8 Twin fixed surface drives in a compact installation

36 | WORKBOAT REVIEW

Steering will be a lot easier if the boat has good directional stability, i.e. it will maintain a set course with only small amounts of correction on the steering wheel. This applies to both displacement and planing hulls and for displacement boats a hull that has a deeper draft at the stern and a skeg will probably track better than one with a shallow level ride. For planing hulls a hull with a deeper deadrise, which may be over 20°, will normally have good directional stability but if you find the boat tending to wander about and be less sensitive to steering corrections you may find that trimming the drive if possible, will improve things because this will lift the bow and trim the hull more by the stern. Too much trim could have a negative effect on the steering and it is a question of trial and error to find just the right amount, something that may not be easy to do when running in waves. We will look at the effects of power trim later on in this chapter and finding the right settings is something that is best done in calm water when you can see the effects of changes much better than when the boat is running in waves. You will also find that boats with dynamic steering will tend to have reduced directional stability because of the much stronger steering effect of the propeller or jet thrust.

The throttle is obviously vital to controlling the speed of the boat but in the case of smaller fast boats it is also used to trim the boat to match the conditions but both the design of throttle levers and their location leaves much to be desired on many boats. You are probably stuck with the control lever that comes with the engine on many boats because the controls and the engine/drive are now closely integrated. Most of these controls are designed for comfortable leisure use where the operations are not critical but they are generally far from ideal for more extreme use.

Because they combine the operation of the throttle and the gearbox into one lever the range of operation of the throttle lever in the ahead position is considerably limited, perhaps covering no more that 30° and this can make it difficult to get the sensitive throttle control required for rough sea operations. It can take only a relatively small movement of the lever to make the change from full ahead to idle when you may only want to reduce the rpm by a few hundred.

This lack of sensitivity in the throttle lever can be exacerbated by the involuntary arm movements that can occur due to the movement of the boat.

Race boats that operate at or close to the limits separate the throttle and gear levers, just using the throttle at sea and the gears for manoeuvring in harbour. It is a system that works well when maximum progress is required and should be considered for any fast boat that has to operate

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THE CONTROLS

under pressure as can be the case with many patrol and SAR craft. You will only appreciate the joy of driving a boat with separate throttle levers and their sensitive control when you have experienced it but it is something well worth considering if you want to drive a fast boat professionally.

Because gearboxes tend to be operated electrically these days the gear lever can even be replaced by a three position switch that you click for ahead, neutral and astern.

The location of the throttle lever (or control box if it is one of the common integrated units) needs to be carefully worked out. The critical part of the throttle operate is the section from full ahead to half ahead. This is the main range you will use when running the boat in waves and so this should be given priority and the throttle lever should be mounted so that this section of the throttle range is more or less upright in relation to your horizontal arm that operates it. This will allow you get maximum sensitivity on the throttle because it requires more movement of the arm (hand) to make changes. However when the throttle is part of an integrated box mounting the lever in this way could make the reverse section hard to operate. On so many boats you see the control box mounted so that the driver has to reach over to operate the ahead section and so he has little sensitivity and very poor control when running in waves.

When it comes to control units for the engines the manufacturers attempt to make a ‘once size fits all solution’ and so it rarely works well in a situation where you want the maximum sensitive control. Many diesel engines come with very short levers coupled to electronic control systems and these can be far from ideal in fast boat operations becuase of the lack of sensitivity they offer. There are specialist manufacturers who make special control units, that will have separate throttle and gear levers and these are worth considering but they tend to be quite expensive solution.

The throttle lever is the most important control in a powerboat when you are operating in waves. Obviously you can use the throttle to control the speed of the boat so that in turn you control the speed of encounter with the waves but one of the important benefits of the throttle in both displacement and planing hulls is that it can also be used to produce quick and short term changes in the trim of the boat. These short term changes can be used to help negotiate the boat through rough seas and particularly in breaking waves in order to produce a faster and safer ride in more extreme sea conditions and also when you want to make the fastest possible progress in adverse conditions. To take advantage of this type of advanced fast boat driving you do need sensitive throttle control particularly when reducing speed when bringing the throttle lever back quickly can result in the bow dropping considerably and perhaps burying into the wave ahead. If you are trying to make the fastest speed in the conditions then the use of the throttle will be constant but on a long passage you are more likely to find a comfortable throttle setting that suits the conditions.

Most throttle controls these days are integrated into a throttle gear control that is supplied by the engine manufacturer. These work well of course and certainly make it easy to operate the boat when at slow speed in harbour but they are rarely the best solution for use in the open sea and they are rarely positioned to allow subtle use of the throttle setting. Like the steering wheel, it needs a delicate hand on the throttle if you are going to use it to best advantage and small changes in the setting can give you the level of control you need. For the combined throttle/gear levers the full operating range may cover perhaps 150° but of this range of movement perhaps 75° will cover the gears,

8 An angled steering wheel can improve steering control

8 Here the steering wheel has been replaced by electronic tiller control

the ahead, neutral and astern engagement. This leaves another 75° of movement to cover the ahead and astern movement of the throttle at each end of the arc of operation.

If you are lucky then the throttle movement may have just 40° of movement to take the speed from idle to maximum which is not enough to allow the subtle control you need.

Add to this the fact that on most installation the ahead section of the throttle range is located on the forward side of the control box so it is even harder to get the subtle adjust you need as you reach over the control box to use it. You will find that you are exaggerating the movement of the throttle from full ahead to almost idling because access to the throttle lever is very poor. If you have to use one of these manufacturer supplied throttle and gear controls than at least install it at an angle so that the ahead section is upright and has priority and is relatively easy to use.

It is not only location that is important. With the modern fly-by-wire systems where the link to the engine is electrical there is not the same level of resistance to movement so you can make inadvertent movements of the throttle lever due to the movement of the boat. It used to be possible to vary the resistance to the movement of the lever with a friction control but this has disappeared with modern systems and it is the same with the steering which has also gone to fly-by-wire and this has made the steering light and non-resistant leading to excessive steering movements because you can’t ‘feel’ them.

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WORKBOAT REVIEW | 37

THE CONTROLS

8 A compact control system in a small patrol boat

So important is the throttle control in lively seas that you should drive the boat with one hand on the throttle and one on the steering wheel at all times so that your reactions and responses can be as fast as possible. This in turn emphasises the need for the careful location of the throttle lever which so that it can be used easily and comfortably.

JOYSTICK CONTROL Joystick control is now available with many drive systems such as stern drives, water jets and pod drives as well as more tailored systems that use the main engines and bow and stern thrusters. The benefits of the joystick are enormous and the level of manoeuvring control is quite amazing, making it possible to position the boat very precisely and to allow it to be moved precisely in any direction. If you need this level of control and instant response such as might be required when docking in tight marinas or on some workboat operations then the joystick solution is a great way to go. At higher speeds when on passage then the joystick control acts mainly as a throttle to set the speed and the steering may switch to a form of tiller steering which may be separate or which may be incorporated into the joystick control system.

There are different types of joystick control that use alternative logic to achieve precise control. One of these allows the joystick to be pointed in the direction you want to travel and then the computer adjusts the drive controls to achieve this. The speed of travel in the chosen direction is adjusted by the amount that the joystick lever is moved in the desired direction. This is the more or less standard format for most joysticks but extras can be added. This type of standard joystick does not alter the heading of the boat so steering can be added and unless there is a separate tiller or wheel the steering can be incorporated in the joystick by twisting the handle in the desired direction. This puts all the control into the one lever and the system can be further enhanced by having a push button in the top of the

With joystick and tiller controls you are putting a lot of faith in the computer controls of the system because it is the computer that translates your commands into actions

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38 | WORKBOAT REVIEW

lever that will engage the autopilot so that the boat will maintain a fixed heading once set. All of this control is literally in the palm of your hand.

This joystick control will normally be available at speeds up to say 10 knots but above this speed the joystick would normally be switched either manually or automatically to a system of separate steering with the joystick just controlling the throttles or in some cases there are separate throttles.

Tiller steering may be offered with no traditional steering wheel but I am not a fan of tiller steering for open sea operations because it is difficult to get the subtle steering control you need. As we have suggested you only want a very light touch on the wheel to reduce the chances of the hull heeling over under more aggressive steering and increasing the hull impact in waves and this light touch is not easy to achieve with a tiller. Also with joystick control and/or tiller steering in rough seas the helmsman does need to be seated and probably strapped in so that he can achieve the best results with the controls and not make inadvertent movements.

With joystick and tiller controls you are putting a lot of faith in the computer controls of the system because it is the computer that translates your commands into actions.

There are usually back up control systems that can be switched in if the computer does not do its job but in a tight manoeuvring situation you are heavily reliant on technology and I have seen the joystick control fail at a critical moment when passing through a swing bridge so it can happen. You have to balance the possible risk of failure against the huge control benefits that the joystick can offer.

POWER TRIM Power trim is available on some types of propulsion and is mainly used on fast boats to give a means of enhancing the performance by optimising the direction of the propeller thrust in the vertical plane. This in turn can affect the fore and aft trim of the boat and it is widely used on deep vee performance hulls. Most outboards over 50 hp and most stern drives have it as well as many surface drive systems.

The power trim is usually hydraulically operated via a trim switch either built into the throttle lever handle or as a separate rocker switch. When a boat comes onto the plane the bow rises and if there was no power trim the propeller thrust would not be horizontal for maximum efficiency but pointing downwards. By trimming the drive the thrust is kept roughly horizontal and this can improve the efficiency of the drive considerably and it can also be used to trim the boat to a small degree. It is a slow acting adjustment and so it tends to be set up for the conditions and then left rather than being adjusted for each wave as the throttle thrust might.

When running at slow speed and when coming onto the plane the drive leg is kept trimmed in so that the propeller has a good bite on the water and the thrust is close to horizontal. It is only when the boat is up onto the plane that the leg is then trimmed out and this is done mainly to keep the thrust horizontal as the trim of planing lifts the bow.

Initially with this alteration of the angle of the drive leg the angle of the thrust from the propeller is changed, making is push slightly downwards in relation to the transom. The change of angle may only be a few degrees but this can be enough to help raise the bow by a similar amount which in turn focuses the planing surfaces of the hull in contact with the water further aft. In effect this reduces the area of the hull in contact with the water and thus reduces the frictional resistance. Flaps could do the same job but they add resistance of their own so are not so effective.

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THE CONTROLS

8 Hovercraft control can be more complex compared to a conventional craft

When coming onto the plane the whole boat lifts and this brings the propeller a bit closer to the surface of the water, reducing the amount of the drive leg in the water and getting the propeller to operate slightly in a surface piercing mode for greater effectiveness. This change may be less noticeable than that done by the change in the hull angle and the amount of power trim applied needs to be carefully judged. The best way to find the right amount of power trim to apply is to experiment in calm conditions when you will be able to clearly see the effect of adjustments. If you have a GPS or speed log in the boat you will be able to optimise the power trim angle for maximum speed and find a setting that works best. You might also find that the boat starts to ‘porpoise’, with the bow starting to lift and fall, if you have the thrust, trimmed too far. This happens because the hull is then planing on only a small section of the hull aft and it finds it hard to find the right balance and so hunts up and down trying to find the balance a process called porpoising.

This optimum setting can be used when running in waves but in more extreme conditions it can pay to trim in a little to help keep the propeller in the water and to ensure that when the throttle is opened you get an immediate response when the propeller bites. It may also be necessary to trim in when executing sharp turns to prevent cavitation but care is needed here with a stepped hull otherwise it might spin out.

When coming off the plane the drive should be trimmed right in. With experience it is possible to look aft of see whether the power trim is set correctly with a smooth flow of water from the propeller being the correct setting. Any sign of a ‘rooster tail’ from the wake and the trim is probably too far out. As with flaps it can help to have an indicator to show where the power trim is set and this will allow you to set the trim at a previously found level. With twin drive systems drives it is becoming common for the trim of both legs to be adjusted through a single switch and there should be no real need to adjust them individually.

The same hydraulics that adjust the power trim may also double up as the means to lift the drive leg right up when beaching, operating in shallow water or putting the boat on a trailer. This tilt mechanism is usually associated with outboards and stern drives and will almost certainly be on a separate switch to avoid confusion and mistakes and if the trim is set up for shallow water work then you must only used low power.

FLAPS AND INTERCEPTORS Flaps and interceptors both do the same job of facilitating the trim adjustment of the boat both in a fore and aft and in a transverse direction. The difference is that flaps are mainly slow acting whilst interceptors can be very fast. It is only likely they will be used on larger boats, perhaps over 6 metres in length where the added complication can be justified. Flaps are hinged plates installed at the bottom outside extremities of the transom which can be angled down under electric or hydraulic control to generate a variable lift on the planing surfaces at the transom. Angled down they will cause the bow to go down and when raised of course the bow will lift and the boat will run on its normal bottom planing surfaces.

Interceptors do much the same job as flaps and are the modern equivalent. Instead of having angled flaps, the interceptor is a vertical plate attached to the bottom of the transom that can be raised and lowered. When it is raised it is flush with the bottom of the transom and has no effect but it only has to be lowered a centimetre of two and it will intercept the water flow coming away from the transom and cause the stern to lift and the bow to lower. It is claimed that the interceptor has less resistance than a flap when in use and of course it makes a more compact installation on the transom with virtually no projections.

Both interceptors and flaps can be electrically or hydraulically operated and with interceptors the adjustment can be very rapid so that they can respond to second by second changes in the boat’s trim.

When both flaps and interceptors are used together they will adjust the longitudinal trim but to adjust the transverse trim you use them individually. If the starboard flap/ interceptor is dropped it will cause the starboard side of the boat to lift and the same with the port flap and the port side. You will probably only want to use this transverse trim adjustment when running with the wind on the beam when a planing hull will tend to heel into the wind at speed but it can also be used to compensate for uneven weight distribution. If you do use the flaps/interceptors individually in this way they will also affect the steering because the flap or interceptor that is lowered creates increased drag on that side, tending to pull the boat round into that direction.

Both flaps and interceptors tend to be controlled by a rocker switch but a form of joystick can also be used. There

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WORKBOAT REVIEW | 39

THE CONTROLS

8 A vertical steering wheel is not comfortable to operate from a seated position

can be some confusion over these switches, some indicating bow down and bow up, others indication flap down and flap up and you need to be clear which is type is fitted to the boat and what movement of the control does. You also need an indicator or dial to show how much flap is down so that you know what is going on at the back of the boat.

To get a feel for the operation of the flaps and how they work try them out in calm water and then it will be possible to see what effect they have when operated together and individually. From this the driver should be able to find suitable setting for operating in waves but with experience he/she will get a feel for the right settings and adjustments.

Because flaps are slow acting you will tend to find a setting that works in the prevailing conditions rather than constantly adjusting them but this setting may need to be reset when course is altered.

RIDE CONTROL The response of the faster acting interceptors has allowed them to be developed into an auto-trim system. Here the movement of the boat is determined by sensors linked to the control computer and the interceptors are adjusted accordingly to counter the movement of the hull to help give a level ride. These auto-trim systems are quite magical in the way in which they can reduce both the pitching and rolling motions of the boat. However bear in mind that the interceptors can only act in one direction, lowering the bow when it might lift to a wave and they cannot lift the bow when that might be the required action and here you might need to open the throttles to get the desired trim for the transient conditions. Trials have shown that by using one of these auto-control interceptor systems in head seas it was

Rolling has always been one of the primary areas of discomfort at sea and these fins which adjust their angle to create a righting force that is designed to keep the boat as upright as possible

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possible to significantly increase the operating speed and the control was much better than could be achieved with manual trim control.

Stabilizers have been around for a long time now and these fins sticking out from the side of the hull can do a great job in reducing the rolling. Rolling has always been one of the primary areas of discomfort at sea and these fins which adjust their angle to create a righting force that is designed to keep the boat as upright as possible. They work well at speeds up to around 30 knots but above that the resistance generated by the fins tends to have too much of a negative effect on the performance and fast boats are less affected by rolling anyway because the movement of the hull through the water produces its own stabilizing effect.

Fin stabilizers also work well on displacement hulls and this is where the maximum benefit can be found. The fins are operated electrically or hydraulically under the control of a computer based system. They are not widely used on workboats because they could interfere with operations taking place over the side of the boat but they could find application on craft such as survey boats.

The main modern option to fin stabilizers is the gyro stabiliser and this has the benefit of working at more or less all boat speeds. This could provide valuable stabilisation to a boat that has to operate when stopped at sea. To match this there are fin stabilizing systems that are also claimed to create a stabilizing effect at zero speed by waggling in response to the hull movements. An interesting alternative is a recent development in the form of the Magnus effect stabiliser. The Magnus Effect is that a revolving cylinder can create a side force when operating in air or water and this is used to create the forces required to counter the rolling by changing the direction of rotation. Their use tends to be limited to slower craft because of the increased resistance of the cylinder sticking out from the boat’s side. They are hinged so they can be swung in when alongside and an interesting development for fast craft is to have them mounted under the transom like an alternative flap system.

Here they can stick out from the hull at slower speeds and then be folded into the transom for higher speed operations.

Adjustable fins and interceptors can also be used to help stabilise catamarans using a series of control fins attached to the two hulls. Here most of these active control surfaces are attached to the hull inside the tunnel between them and they can be particularly valuable in controlling the pitching movements. A further development of this is to see vertical interceptors attached to the outer sides of the hulls where they can be used for steering but they only work when the vessel is moving ahead at reasonable speed.

The Hull Vane was developed in Holland as a means of improving the performance of mainly semi-displacement hull. It is a fixed transverse aerofoil that is attached to the transom where it serves to improve the efficiency of the hull by adjusting the trim, resulting in improved performance and/or reduced fuel consumption as well a providing a more level ride. Now the company is working on a Dynamic Hull Vane which is claimed to be able to act as a pitch stabiliser.

Here the angle of the vane can be adjusted hydraulically to provide the stabilisation.

Having the ride controlled by fins, foils and interceptors can give a much more comfortable ride but because the boat’s movements are being controlled to counteract the waves the hull can generate a lot more spray so one of the penalties of active ride control can be a wet boat. Then it becomes a question of designing the hull to control this spray.

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THE CONTROLS

BALLAST TANKS Particularly on fast boats, controlling the pitching can be important when fast progress is required. Careful location of the longitudinal centre of gravity can be important but once established by the designer it is not variable.

Pumping water or fuel from one tank to another is one possible way to vary the LCG but of course will not work when tanks are close to empty and many racing boats used a system with a bow ballast tank that could be filled via operation of a dashboard control. Now, following extensive testing and evaluation this bow ballast system have been shown to produce significant improvements to the ride of RIB rescue boats of between 7 and 8 metres in length in operation with the RNLI and this would appear to be something that could have application to patrol boat operations. In some of the testing the severity of the impacts going into a head sea were reduced by half which is a significant difference.

The bow ballast tank usually forms a part of the boat’s structure so there is very little increase in weight and it fits into an area that is usually a void space on most boats anyway. Rather than use a pump, the emptying and filling

of the tanks is done by using the boat’s forward motion with a scoop attached to the transom. This can be lowered by operating a mechanical dashboard control so that it protrudes below the transom and the water pressure created by the forward motion of the boat rapidly fills the bow tank via a pipe running through the boat. A small vent pipe in the deck at the bow indicates when the tank is full when water comes out of it so that the scoop can be retracted, shutting off the flow. To empty the tank a drain valve is opened and gravity allows the water drain away.

Many ways have been developed to help control boats operating out at sea and the effectiveness of these systems has to be balanced against the increased complexity and cost of the systems. There can be pressure through shock mitigation requirements to reduce impacts particularly in work and patrol boats and these various control systems can help by an important consideration is still in the way that the driver operates the controls. Getting the right controls and having them in the right positions so they can be operated effectively is a major part of modern boat design and one particularly applicable to work and patrol boats operations.

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WORKBOAT REVIEW | 41

ELECTRIC & HYBRIDS

CHAPTER SEVEN

Credit: Swedships

ELECTRIC AND HYBRIDS

8 A Swedish lifeboat with a hybrid electric/ diesel system installed

We are seeing a considerable push towards using electric power on many types of workboat and for many workboats there can be considerable benefits in using electricity for certain types of operation. Certainly there are more advantages for workboats than in the leisure sector where electric propulsion of one sort or another is heralded as a way of saving the Planet rather than offering any significant energy or fuel savings. Carefully planned electrical installations combined with diesel generators can offer benefits, particularly where there can are widely different loadings on the propulsion systems during normal operations. That is just one of the options on offer when it comes to using electricity for the main propulsion and it does seems that with so many options on offer the market is somewhat confused and this is what could be leading to a reluctance to switch to electric propulsion.

Electric propulsion has been hailed as the future solution for boats but whilst it certainly has its merits for some applications it certainly is not always the solution to reducing emissions that it is hailed to be. For cars there can

be a benefit to hybrids or electric drive because it allows energy to be recovered from braking and going downhill which helps to reduce consumption. With boats they are neither braking nor going downhill (you hope) so there is no possibility of energy recovery so somewhere you have to pay for the energy you use. With hybrid systems you mainly have to generate the electrical energy onboard which entails emissions from the diesel generators. With a pure electric system that only has electric motors you have to power the batteries from shore power. Whilst the operation of the boat itself is emission free that shore power has to be generated somewhere which will usually entail emissions being generated unless it can come from renewable energy sources.

Then there is the efficiency of electric systems. Every time you charge a battery you are probably loosing about 10% of the power through the charging process. Then you will loose another 10% when you take the power out again so the overall efficiency can be poor. There are also losses in the system itself through heat and the electric motors need to be water cooled so there are more losses there. So don’t be beguiled into thinking that you are saving the planet by going electric. It might help reduce pollution in some sensitive areas but it is not necessarily the ‘clean’ energy that it seems to be. Let us have a look at the optional systems on offer.

Credit: Enchadia Marine

8 Electric drives with the motor in the hub

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PURE ELECTRIC PROPULSION These are boats with a bank of batteries installed, which is the fuel and for propulsion there is an electric motor coupled to the propeller shaft. This is the simplest type of electric propulsion to operate the boat and some commercial users could see a significant future in electric propulsion of this type. Operators such as harbour authorities where their boats only operate in a limited area that is possibly emission sensitive and where frequent recharging is possible could see a significant benefit in using electric

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ELECTRIC & HYBRIDS

propulsion. Fast charging systems are now available which could also open up the electric boat market to water taxis and ferries where charging can take place at dedicated stops. As harbours and inland waters are likely to be those areas that are sensitive to pollution of one sort or another, this is where we are likely to see a take up and expansion of electric propulsion of this type.

To further simplify this type of craft there are electric outboard motors with powers up to 80 hp at the time of writing and these can make installation simple, Most are available with a dedicated battery system and a control unit that can add to the simplification of the installation.

The most important feature of such an installation is the ‘fuel’ gauge that shows the amount of charge left and once the crews get used to this type of ‘fuel’ then an electric boat can become viable. With petrol or diesel as a fuel you would never really worry about running out of fuel but for some reason you get very concerned on an electric boat when the battery charge start to run low, perhaps because you cannot tip a reserve can of fuel into the tank to get you home. There is always the option of carrying a portable generator on board as a back-up or fuel reserve. Solar panels can also provide charging when in operation and there are mainly tourist boats that operate only with charging from solar panels.

The reliability of electric propulsion has reached the level where electric lifeboats have now been approved for use on ships and offshore oil platforms. The attraction here is the much reduced maintenance and the simplicity of the installation with the possibility of monitoring the systems from the shore to ensure reliable operation in an emergency.

Electric propulsion does not require a gearbox and you have a motor that can operate from zero rpm to full power with no minimum idling speed which can enhance manoeuvrability and be a bonus to harbour operations.

This sector of pure electric boats is now undergoing change with battery and motor developments are now allowing this category of electric boats to reach planing speeds. Motors are operating at higher voltages, up to around 480 volts DC, which helps to allow compact, lightweight and powerful motors. Speed and weight are

closely related in small planing boat design so that the performance challenge is to install a battery pack light enough and powerful enough to allow planing speeds combined with a useful range.

Whilst much of the focus on boats with electric propulsion is with the battery systems there are also developments with electric motor design that offer considerable improvements in efficiency as well as reduction in weight.

Most electric motors on use permanent magnets or an electric current passing through coils of copper to create the magnetic poles and fields that make the motor turn. New motors that have been developed by Volabo use a cage made up from aluminum strips to create the magnetic field and by pairing these strips in alternative ways a variety of different magnetic pole formats can be created, each combination giving the motor different characteristics.

With conventional electric motors the designers try to find a balance within the set parameters that creates a good compromise between the RPM, the torque and the efficiency.

With the new motor the ability to vary the pairings of the coils means that these parameters can be varied to match the demands on the motor and this gives a lot more flexibility for marine operation. For instance the motor can be programmed to provide a high torque when the boat is coming onto the plane and then the torque can be reduced and the RPM increased once on the plane.

With the Volabo motor the control of the various pairings of the coils is done under electronic control so that the operator does not have to make any adjustments. The designers claim that one of the advantages of the new concept is that more powerful electric motors can be used whilst still operating at the relatively safe voltage of 48 DC. The first marine application for a Volabo motor is rated at 50 kW. The motor is compact with a diameter of 30 cms and a length of 45 cms and the total weight of 60 kgs figures that include the control system. 48 volt motors up to 300 kW are thought to be feasible.

In America ECM is developing technology that involves replacing the conventional coiled copper wiring of the stator of the motor with a printed circuit board (PCB). The resulting PCB stator motor is seen initially as a valid

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8 A diagram showing the elements of an electric hybrid system Left: Electric ferry

8 A steerable electric propulsion system

WORKBOAT REVIEW | 43

ELECTRIC & HYBRIDS

8 A electric ferry connected to an induction charging system alongside

8 An electric propulsion system that allows simple installation

replacement for many of the electric motors found on ships and boats that power systems such as pumps and air-conditioning units.

ECM replaced a 3hp air handler motor with a 3hp motor integrated with PCB stator technology. The motor that was replaced weighed 45kg and operated at an efficiency of 87.5%. The solution developed by ECM was a third of the weight of the motor it replaced and operated at an efficiency of 91.6%. Increased efficiency and a considerable weight w reduction are only a few of the claimed benefits when a motor is upgrading with a PCB stator, making the technology applicable for almost any application. At present the technology has been expanded e to produce motors of up to 13 1 hp and one marine application being b explored is as a propulsion motor m for a USV with several in operation o at the current time.

The company says that the motors are scalea scaleable to multi-megawatt sizes and have a variety var of maritime applications including propulsion p and generators. Infinitum is another US company work on the same concept and an they are currently offering a 15 hp PCB motor. These developments could herald a revolution in electric motor design that combined with more efficient and lightweight battery systems could be the catalyst for a much wider application of pure electric propulsion for workboats.

HYBRIDS Rather than have full electric propulsion we are seeing boat builders offering boats with hybrid systems. These have both electric and diesel propulsion and with most of them you can stop the diesel and switch to electric drive using the same propeller shaft. The electric motor is simply clutched in or more likely it is the diesel engine that is clutched out and you can go silent for short distances on battery power. Most systems allow the electric motor the act as a generator when the diesel is running so the batteries are kept charged up when you use the electric drive intermittently. The systems can become quite complex and are usually computer controlled for the switch over and to control the battery charging. Solar panels might be added to the system if the boat design allows for a free charging boost.

Therefore on a standard marine hybrid system you will not save any emissions or fuel in normal running except in

44 | WORKBOAT REVIEW

special applications such as with tugs where there can be a wide difference in power requirements during towing and running light where the hybrid system can help with the difference. In general use a hybrid system could in fact burn more fuel because every time the electrical energy from the on-board generator is fed into the batteries or taken out and then used in the motor there are those power losses to consider. This would make the hybrid system generally less efficient than a conventional diesel drive. If you can charge the batteries from a shore supply then you will probably get cheaper energy but that will only last for a relatively short time depending on the size of the battery bank. So these hybrid systems tend to be required mainly where boats have to operate in sensitive areas or where the electric propulsion can be used to reduce the operating hours of the main diesel or to prevent the diesel engine(s) having to operate in light load mode.

A third possibility for hybrid systems is possible where the electric motor is used to help balance out the varying power demands on the propulsion system so that it can provide extra power when required thus allowing a smaller diesel engine to be installed or to provide the main propulsion when only a light load is required such as in loitering. There are many workboat operations that have to operate with this type of variable loading such as a pilot boat having to loiter, waiting for a ship or a tug in towing operations. It can be a viable option for vessels operating in dynamic positioning mode and perhaps for wind farm vessels when they are operating at slow or zero speed when at the turbine. An example of creative use of a hybrid system is seen in police patrol boats ordered for Venice which can operate at low speeds under electric power in the canals but at 30 knots under diesel power in the open waters.

DIESEL ELECTRIC SYSTEMS The third way with electric propulsion for boats entails using a diesel powered generator to provide the electrical power which is then supplied direct to the electric motors that are the main propulsion system used to propel the boat. This is the traditional diesel electric system but today such systems often have a bank of batteries built into the circuits to offer more flexibility. With such a system there can be significant advantages with one being that the generator/s can be located in any part of the boat or ship and a single generator could supply two propulsion motors so saving on cost and space and giving design flexibility.

Also a generator running at a constant speed can be more fuel efficient than a direct propulsion diesel that may be optimised for a running speed different to that being used.

An added advantage for electric propulsion is that you can get much more sensitive manoeuvring with the electric motors which unlike a diesel, are capable of operating from zero speed upwards and no gearboxes are required.

8 This ferry is an early conversion to electric propulsion

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ELECTRIC & HYBRIDS

In general use a hybrid system could in fact burn more fuel because every time the electrical energy from the on-board generator is fed into the batteries or taken out and then used in the motor there are those power losses to consider

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If the electrical power is provided by two or more generators there can be saving by having just one operating at an efficient fuel saving speed and the other switched off rather than having one large generator operating inefficiently when only lightly loaded. There might be some merit in having a series of smaller generators rather than one or two larger ones. The smaller units could be cheaper and allow more flexible installation as well as providing good redundancy. Having two or more generators also provides a back up in the case of failure and the addition of a battery bank into the system also provides additional flexibility in the way that the system can be operated. An example of this type of operation can be found in ferries that may require full power for the crossing and then low power for the final manoeuvring alongside and perhaps to also hold the ferry alongside. Two or more generators and a battery bank would offer considerable flexibility to match the load to the requirements with the possibility of considerable fuel savings. Once again computer control would be required in order to optimise the system for maximum effectiveness.

PROPULSION SYSTEMS For many of the applications of electric propulsion a conventional shaft and propeller system is used but we are now seeing some dedicated electric drive systems appearing on the market. Some of these derive from the Sail-drives developed for the leisure market where the vertical shaft of a pod drive system has an electric motor at its top end driving directly to the propeller. These are fine for low power applications but for workboats some of the drive systems have been converted to electric propulsion with the new Woolwich ferries having four Aquamaster units coupled to electric motors. Dutch company Hydrostra has developed a combined electric motor and pod propulsion system that is being used for some tourist vessels operating on the Amsterdam canals. This steerable drive unit offers 100 kW and provides a self-contained electric propulsion unit for simple installation. They operate on 400 volts AC and the company also has the control and power conversion systems to match and this is a good example of the increased use of fully integrated propulsion systems.

Drive system specialist Schottel offers similar systems in higher power capabilities.

One of the reasons for operating electric motors at higher voltages is that the motors can be more compact. This allows the electric propulsion motor to be small enough so that it can be incorporated in the hub of an azimuthing drive unit which is similar to the systems used to power many of today’s cruise liners. On a smaller scale this is being developed as a system for steerable pod drives with the added benefit that the electric motor is underwater and it can be cooled simply by the water flowing past rather than requiring a separate piped cooling system. Higher voltages allow very compact electric motors and Siemen’s

has a 200 hp electric motor that is just 50 cms long and 20 cms in diameter, and relatively lightweight which operates on 400 volts AC. The AC motors can be controlled by frequency modulation that has reduced power losses and the whole installation is computer controlled with a read-out of power and range remaining at any time. 400 volts AC is a very high voltage to install in a boat so the installation has to be very well engineered for safety although the higher voltages also offers the benefit of requiring smaller diameter wiring and reduced weight.

8 A hybrid system combining diesel engines and diesel generators

BATTERIES SYSTEMS Batteries are the Achilles’ heel of modern vessel electrical systems. They add considerable weight to the boat which may not be a problem for displacement boats but which has prevented any widespread adoption of electric propulsion for planing boats so far. The batteries are relatively high cost and at present they have to be replaced perhaps every 7 years, adding to the costs of running an electric boat which could be quite considerable.

Virtually all of the electric vessels on the water today use lithium ion batteries which are lighter and more efficient than traditional lead acid batteries. They can also be charged rapidly and do not deteriorate in the same way as lead acid batteries although they need renewal probably every 7 years depending on their use. To produce the high voltages required in modern installations a large numbers of cells have to be connected in series and then the direct current from the batteries has to be converted into AC for

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8 A conventional electric motor compared with the printed circuit board motors (front)

WORKBOAT REVIEW | 45

ELECTRIC & HYBRIDS

8 A low resistance catamaran hull is effective for electric propulsion

the motor if that is the chosen system but the technology for this is now compact and automatic these days The cost of these lithium ion batteries has come down considerably over the past two years largely because of competition from Chinese imports and more extensive use of these batteries in road vehicles where much of the development is taking place. There is considerable power stored in a large battery bank and with this comes a fire risk but this is being overcome with built in detection and extinguishing systems and lithium ion-phosphate batteries are claimed to be safer. A variety of alternative battery types are under development and one promising avenue that offers an alternative to batteries for some applications could be super capacitors. One of the first uses of capacitors in the marine world is on a 24 metre French ferry where this all-electric vessel has super capacitors to store

the electrical energy in place of the normal battery systems with a considerable saving in weight and cost. This new ferry is designed to operate on a short route of just a couple of miles across the river at Lorient with rapid charging at each end of the route. The design of this ferry and its innovative electrical propulsion system has been carried out under a research programme called ECORIZON R & D programme. Builders STX Lorient and Stirling Design International were involved in the development work.

The super capacitor electrical storage system is an extension of the technology found in energy recovery systems such as that used on some road vehicles and on Formula 1 cars in their KERS system. These store the energy that would normally be lost due to braking and make it available for powering electric motors when acceleration is required. On marine applications there is no

8 An electric ferry showing the induction charging panel on the side (black)

46 | WORKBOAT REVIEW

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ELECTRIC & HYBRIDS

opportunity for energy recovery but on the ferry application the super capacitors can be recharged very quickly so this can be done every time the vessel docks and this can provide enough power for the vessel on the short route of the Lorient crossing.

The capacitors are much smaller and lighter in weight than batteries and crucially they should not need replacing at regular intervals like batteries. However they are only suitable for high discharge rates over a short period. On the ferry application solar panels are installed on the deck above the saloon to supplement the capacitor power and a diesel powered generator has been installed with adequate power to propel the vessel to offer more operational flexibility when the vessel is used for cruising operations.

Looking further ahead there are battery developments such as the aluminium -air battery which takes away the use of more exotic materials such as lithium and also offers a saving in weight. British company Amberjack has new lithium ion batteries under development that use nanotechnology to improve both efficiency and the power/weight ratio. Several companies are working on the concept of solid batteries where there is no liquid electrolyte but these are likely to be some years away from introduction for marine use. Improved batteries and/or capacitors are the key to improved efficiency and it is their weight and capacity that can often be the determining factor for electrical propulsion viability. The mass production of batteries that is now developing should lead to cost reductions and for the future it looks as though costs will come down as the marine sector rides on the back of the car industry applications.

COSTS AND APPLICATIONS From current experience it seems that the cost of any vessel equipped with electric propulsion is going to be higher that one using conventional propulsion with diesel engines.

Some estimates put this increased cost in the region of 10% of the cost of a diesel engined version which is a significant increase in capital costs. This high level of cost can only be justified if there is the promise of considerable fuel savings and it would be rare to find the potential reduction in emissions and quiet running to be adequate justification for this additional cost in the commercial sector. Unlike the leisure sector where these virtues are promoted as the reason for adopting hybrid of full electrical systems the commercial sector tends to operate on hard commercial costs. This means that an electrical hybrid propulsion installation has to be justified by long term fuel savings and perhaps reduced maintenance costs.

Many electric boats are being based on fuel efficient hulls which is fine for specialised applications but it immediately suggests that electric propulsion is not viable for general use. One example of how hull design and electric propulsion have to considered in tandem comes from French company Remora. They have developed an electric RIB specifically designed for harbour and marina use. Based on a 6.45 metre trimaran hull for efficiency and stability this boat can operate all day on one electric charge. The Remora offers

The super capacitor electrical storage system is an extension of the technology found in energy recovery systems such as that used on some road vehicles and on Formula 1 cars in their KERS system

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8 The electric motor of an electric powered ship’s lifeboat

pollution free operation whilst being completely silent so that is can operate in sensitive areas and its low draft and height clearance will allow it to access all parts of a marina or port. The two 4 KW propulsion pods are installed in the outer hulls of the trimaran so that they allow good manoeuvrability. These are steerable pods with the motors housed in the hub of the pod.

This example is perhaps outside the mainstream of workboat applications and it might suggest that electric propulsion will only apply to special applications. However the increased use of electric and hybrid systems does suggest that it is growing in popularity in the workboat sector and that it is moving into the mainstream as the potential cost savings are balanced against the increased complications and capital costs. There have been tentative steps in developing planing boats with electric propulsion but viable fast electric patrol boats would appear to be a few years into the future.

Looked at purely on a cost/benefit basis electric propulsion may be hard to justify but for many workboat applications there are also increasing demands for reducing emissions which could be a factor in helping to make electric propulsion a viable option. Increased demands for green operations particularly in ports and sensitive areas could be a factor that may overcome this cost hurdle.

Electric propulsion still has a long way to go but we are seeing the momentum growing for wider adoption.

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ELECTRONICS

CHAPTER EIGHT

ELECTRONICS information. Officially the human is fully in charge but you have to ask how decisions can be influenced by the electronic information and the trend is certainly towards reliance on electronics whilst officially it is the human who is responsible.

8 Dedicated to electronics, the controls on a Norwegian lifeboat

Today electronics play a vital part in nearly every workboat or patrol boat. Not only do they generate most of the navigation information but electronics now control the engines and the fuel system, plus communications and they also play a vital part in safety.

Then there is the specialist equipment that can be found on many boats such as survey equipment, dynamic positioning and research systems. It is a fast expanding sector that now plays a vital role in virtually every work and patrol boat and selecting the right equipment can be a challenge with much depending on the role of the vessel and its operations. The role of electronics will expand even further with the move to greater use of autonomous systems.

For fast craft with speeds over say 30 knots, navigation electronics have revolutionized the way they operate.

Before the advent of GPS it was a challenge to navigate these craft particularly at night or in fog but electronic systems have made these operations both safer and more expedient. It is the same with search and rescue where electronic systems play a vital part these days but the same can be said for virtually every type of workboat and patrol boat where they are required to operate in adverse conditions and where delays cannot be tolerated.

Here we will look at the main types of equipment that can be selected as well as focusing on how it might be installed and the pros and cons of different equipment for specific purposes. It is a fast changing market sector with not only new equipment arriving nearly every year but new systems and new developments and if you follow these developments to their logical conclusion it leads to the automated work and patrol boat where there is total reliance on electronic systems. Currently with manned craft there is no longer a clear divide between what the humans can do and what the electronic systems do and how much reliance can be placed on the electronic derived

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RADAR Radar was one of the earliest electronic systems fitted to work and patrol boats and today it holds a unique place amongst marine electronic systems. Almost all electronic systems are precise and produce absolute answers with no negotiation but with radar there are no guarantees that it will show everything out on the water that is within range and the information shown on the display has to be interpreted by the user. Whilst developments continue to improve the capabilities of radar it suffers mainly from the problem that the radar returns from waves can sometimes be stronger than those from small targets such as boats and buoys. This can be a challenge when using radar in poor visibility because if you can’t detect something then you can’t take avoiding action.

Much of the improvement in modern radar systems comes from analyzing the radar returns in some detail in order to get more information from the returning signal. With earlier systems the radar return was taken at face value with the size of the displayed target largely relating to the size of the target but both wave and rain clutter were problems that also created radar returns and so discrimination between wanted and unwanted targets was challenging. One way that the radar returns can be analysed is to look at the Doppler Effect on the returning signal. The Doppler Effect means that the return from a target that is moving either away from or towards the receiving antenna will be changed from the original and thus by analysing the returning signal the radar can tell if a target is moving towards or away from the antenna. In this way not only can useful information be presented to the operator as an aid to collision avoidance but it can help with differentiating smaller moving targets from fixed targets.

8 The best type of autopilot with a rotary course setting control

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ELECTRONICS

Another way to find small craft or buoys amongst the sea clutter is to check the consistency of the radar return. The return from a wave is likely to be transient whilst that from a small boat should be constant and in this way target identification is possible but not 100% reliable. This really sums up radar, it is a considerable aid to collision avoidance which is its main use these days but it cannot offer 100% certainty which means that it requires a skilled operator if it is going to provide useful answers in poor visibility which is why most operator qualifications demand a radar operator’s certificate.

The radar antenna and the type of signals transmitted have moved on from the past. Now we have beam sharpening, pulse compression and broadband radar, all of which are designed to create sharper images on the display with better discrimination between targets, particularly those close by. The display of the modern small craft radars is a major step forward in terms of quality and detection but it still cannot offer that 100% detection that is required.

One future development that may resolve this is to combine the radar detection with other sensors such as low light TV or infrared cameras. By combing these technologies it may be possible to get very close to that 100% detection required. We will look at these alternative technologies later but at present they tend to work with a

fixed or manual camera that is not compatible with the rotating radar antenna.

Modern radars used on smaller craft tend to be very reliable these days because they are based on solid state electronics and they are housed in watertight cases so can be used in exposed position on the vessel. Colour displays make discrimination much better and the radars can be interfaced with the other electronics on board to allow the radar to be superimposed over the electronic chart and as means of confirming the accuracy of the GPS position.

Whilst radar is fitted primarily for navigation and collision avoidance on work and patrol boats it is being developed for other uses. Two companies have used the returning radar signal to give an indication of the height of approaching waves. They take the returning wave clutter and from its intensity it is possible to separate the higher from the lower waves. This can be valuable information for vessels that are carrying out lifting operations or alongside offshore installations as it can give early warning when larger than average waves might be approaching allowing operations to be temporarily suspended. This can allow operations to be carried out in adverse conditions in the knowledge that warning will be given when the conditions need to be temporarily suspended.

8 A dedicated AIS Display which is no substitute for radar

POSITION FIXING Navigation has been transformed since GPS was introduced and became widely available in 2000. That was when high accuracy positioning was available to commercial and civil users and the system is in the process of being upgraded again. It brings reliable and high accuracy positioning 24 hours a day and whilst the lat. and long. position itself is not of much value, it becomes the basis of navigation when it is plotted on a chart and the position can be seen in relation to dangers and other navigation features. In addition to electronic charts, GPS also forms the basis of AIS and can be used in other systems such as fuel calculations and compasses.

Following on from the US based GPS other countries have developed their own satellite navigation systems. The EU has developed Galileo which is now coming on stream, 8 An augmented reality display compared with the radar/chart display

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WORKBOAT REVIEW | 49

ELECTRONICS

8 A Class A AIS receiver with dedicated display

8 Dome antenna for satellite communications and entertainment reception

the Chinese have Bieu Die and the Russians have their Glonass system operational. These are all international systems covering the globe but there are other local system that some countries have developed as well so satellite navigation is well established.

These days we reply heavily on satellite systems for navigation but what happens if it goes wrong? GPS has such a long history of providing reliable service that we don’t contemplate its failure but it can be vulnerable. Apart from physical damage and loss of power supplies the real risk comes from jamming and spoofing.

These are relatively new threats to GPS and you might think that att the th th alternative satellite systems will provide back ck up ck p but they all operating on frequen frequencies ncies that are close together and it is likely that if one is jammed they will all be jammed in a particular locality. The GPS si ssignal gnal from o those distant satellites is very weak when it reaches the earth’s surface and it is so weak that it has been likened to looking at a 100 watt electric light bulb from a distance of 100 miles away. Any weak signal like this can be affected by other stronger signals in the vicinity. This type of jamming could be intentional or unintentional but what is sure is that jamming of the GPS signal is a very real possibility and could lead not only to GPS failure but also to error positions which could be even more dangerous to navigation.

There is accidental jamming when a truck driver parks up and sets his jammer going so his bosses can’t locate him but that jammer could affect GPS receivers out on the water as well. Then there could be malicious jamming perhaps from terrorists so the risks are there. Spoofing is when the system is taken over and gives out false positions which is perhaps more dangerous. Alarms will probably sound is either case but as a navigator it can leave you in something of a dilemma particularly when you reply on position fixing to carry out specific operations.

There are anti-jamming boxes that you can install into the antenna system and other protection systems use

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antenna that only pick up signals from high elevations on the assumption that a jamming signal will come from a low land based elevation. The risk of disruption to satellite systems is leading to calls for a back-up with E-Loran an enhanced version of the old land based Loran system claimed to be able to provide accuracies close to those of GPS but because it operates on hard-to-jam long wavelength frequencies is far less vulnerable to jamming. It has been mandated to be established around the US but there seems to be a distinct lethargy about implementing the systems in Europe.

ELECTRONIC ELE LE LECTRONIC E CHARTS It was the advent of GPS that made electronic charts viable and today they are the primary means of displaying navigation information. Today the charts are almost entirely digital charts which offer a flexible approach a proach to displaying ap information wit w with h the alternative raster charts, which are literally a photo of the paper chart now being mainly discontinued. The chart displays have become very flexible and it is possible to get satellite overlays and 3-D type of displays that show the underwater contours quite graphically but for most navigation purposes the conventional 2-D chart display is favoured.

The relatively small size of the electronic chart display does mean that you need to work differently to when using paper charts. You have little idea of scale and when passage planning you can set out the basic route but then it is necessary to expand the scale to check the route in detail because so much detail is left out of the display on large scale charts. On a slow workboat there is time to explore the electronic chart but on a fast patrol boat the challenges of using these charts can be apparent. This is particularly so at night when you have to do a double or triple click operation in order to find out the character of a buoy light. Of course you can always write them down beforehand but the scale of the chart rarely allows them to be display on the screen.

The big bonus with the electronic chart is that the position is automatically and continuously plotted for you so that you can immediately see where you are in relation to where you want to be. There can be two heading markers, one showing the actual heading at the time and the other showing the course being made good so it can be a very simple matter to adjust to course to maintain the desired track.

Manufacturers are incorporating so many bells and whistles into modern electronic chart systems that they have become overly complex. For most navigation purposes the basic chart display combined with the position and heading is all that is required. It is possible to get the radar picture overlaying the chart and this can give a good overview of the navigation situation and with chart and radar you can check that the GPS is functioning correctly if fixed targets coincide on both but collision avoidance can be harder on such a combined display. Today you get touch screen control which does not work too well when the boat is pounding in waves and finger control can be challenging and is quite a blunt instrument. The alterative controls tend to be push button rather than rotary knobs which again do not work too well on a fast boat. The chart units are becoming a one size fits all development and the specific requirements of fast boats are not considered.

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ELECTRONICS

SOUNDERS AND SONARS AND LOGS Sounders were one of the first bits of marine electronic equipment found on workboats and whilst the basic concept has remained the same the presentation of the depth information has changed considerably. What started as a stand alone piece of equipment is now generally incorporated into the main electronic displays so that the depth can be called up either as a digital read-out or as a graphic chart showing historical as well as current data.

Now the principle of sending out a sound pulse and taking the time before it is reflected back from the seabed has expanded into side scan sonars and multi-beam sonars which are mainly used for survey work.

Like radar many modern sounders and sonars can analyse the return signal in order to extract more detailed information. Of course the fisherman a uses tthe e so sonar a to pinpoint shoals of fish but it is also lso possible to identify the material of the seabed bed from the retuned signal. Specialist sonars nars are used to detect underwater pipes and cables and this is of growing importance with the development of offshore wind generation. With this expansion n of the use of sonars, the basic sounder still has relevance as a navigation tool when it is used to match the charted depth with the actual depth as a means of confirming the position developed by the GPS. AUTOPILOTS The autopilot is a ubiquitous piece of electronics that is fitted to most workboats these days. They are so common that it is hard to picture ture going to sea without one. Their obvious use is to relieve the helmsman off th the b burden d off steering the boat so that instead of focussing on the compass he/she can focus on the lookout but there can be many more advantages to steering by autopilot.

Because the autopilot can do a much better job of maintaining a course than manual steering it can save fuel.

By not wandering off ccourse as is the case with manual steering it is reckoned that the distance covered on a p passage can be reduce reduced by as much as 5% which eq equates to burning 5% less fuel. fue On a fast planing boat the th straight course steered stee by the autopilot can greatly improve the comfort com of the ride because becau the boat does not heel over as ste steering is applied. The course is corrected by just small a adjustments of the steering t i which hi h nott only l stops t h heeling li but which should allow you to maintain a higher speed.

The autopilot can also be used going into and coming out of harbour. This is a time when you need to concentrate of what is going on around you, a time when the navigation can be under pressure and where there is increased risk of

8 Electronic systems are vital to maintain ferry services in all weathers.

Inset: A satellite antenna to give worldwide communications

8 The displays of three camera systems, normal, low light TV and infrared

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WORKBOAT REVIEW | 51

ELECTRONICS

is rarely prominent whilst it can be a real problem at night when the push button is not illuminated and you need to find it quickly. Then there is the question of how you alter the course when under autopilot control. On many yacht types of autopilot there are two select buttons, one giving an alteration of 1° which allows you to fine tune the course and the second one usually gives you a 5 or 10° alteration in one go. You can get used to these but particularly when you are entering harbour it is much better and easier to have a rotating knob for course control. Then you can operate it just like a mini-steering wheel and that works fine.

8 A compact small workboat radar and antenna

8 It is vital to get display lighting correct for night use

collision so you need to focus on what other vessels around you are doing. Trying to do this and to concentrate on the compass and/or steering the boat and you can soon reach a state of overload meaning that you don’t do any of these tasks properly. Using the autopilot can at least relieve you of having to concentrate on the compass and with the right design of autopilot it is very simple to adjust the course and let the autopilot hold the heading on the new course. A joystick control will often give you the same effect when you press the button on the top of the joystick and the current course is maintained.

For work and patrol boats you need the correct design of autopilot and many yacht designs are not very effective.

Firstly you need to be able to switch from autopilot to manual control quickly if you suddenly see something close ahead that you want to avoid such as floating debris or perhaps breaking waves. So often it can be hard to find the standby switch that performs the on and off control to switch back to manual steering. Even in daylight the switch

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NIGHT VISION AND LOW LIGHT CAMERAS There are two types of these cameras, one using infra red to detect targets from their heat signature and one enhancing the available light to convert night time into a virtual daylight. It is low light cameras that can be of most use for general navigation at night, producing a picture on a display that can show what lies ahead as a visual presentation. These can be valuable for fast craft in particular although the portable units that are on offer do not work well on a moving boat. A fixed display is much easier to interpret and would be the favoured option combined with a camera that can be moved in azimuth to direct it towards a target.

Infra red cameras can be useful in poor visibility to confirm targets that can be seen on the radar and would make a good combination to work in conjunction with radar. However, like the low light camera an infra red camera is fixed and only covers a small arc of the horizon so its use tends to be limited to areas directly ahead. Future developments may see both of these types of camera linked to the radar antenna so that it would be possible to scan

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ELECTRONICS

the sea with a triple system of radar, low light and infra red that would be likely to detect every target out there. What one system might miss one of the others would likely detect it but such a system is still some way off in development.

AIS Automatic Identification Systems (AIS) can produce very useful information about other vessels around you and show their position and course on a display that can be a radar or chart display. It is a significant development in collision avoidance but it suffers from one big disadvantage, the AIS returns will only show from other vessels that are fitted with AIS. AIS is mandatory on vessels over 300 tons but it is also fitted to many leisure craft and smaller vessels but there can be any number of smaller craft out there that do not have an AIS. This means that there are no guarantees that AIS will detect every vessel on the seas so that smaller craft tend to become ‘invisible’ and because they do show an AIS return they become second class citizens out on the water and their presence is likely to be ignored by shipping.

It seems likely that every work and patrol boat would be fitted with an AIS unit except perhaps for some smaller harbour craft and RIBs. Many marine VHF sets have an AIS incorporated into them these days because the system uses the VHF frequencies for transmissions and of course they need a GPS or similar input to enable them to work.

Although the main information such as position, course and speed are processed automatically, the system does need some manual input such as the next port of call, and the vessel details and possibly cargo or reason for the voyage.

ALARMS These day it seems virtually everything on board has an alarm of some sort and getting to understand and cope with alarm systems can be complex and time consuming.

An alarm sounding is often put down to a known fault or to a faulty sensor and the crew go to sea without any concerns but any alarm has to be taken seriously otherwise alarms lose their purpose. If alarms are going to do their job and they can play an important role in safety then we need to have a much better understanding of the role of alarms and what they indicate.

Alarms can be divided into two main categories. There are those alarms that can indicate some form of imminent danger and these could be items such as bilge alarms to indicate that water is rising in the bilges or perhaps fire alarms, alarms that indicate that immediate action is required to prevent disaster. Similar warning alarms can be found in the electronic navigation equipment such as the radar and the chart plotter and these can warn of GPS failure or of the boat approaching shallow water or that there is another vessel on a collision course. Less urgent alarms might give warning of a problem with the engines or perhaps low fuel or even if some hatches or portholes are left open. It would be nice to think that every alarm has a defined purpose but amongst the current alarm systems there do seem to be some that are less than important.

An alarm sounding can easily divert your attention from finding a solution to the problem. Surveys amongst watch keepers on board ships have shown that over 50% of the people say that they just ignore any alarms and switch them off without any investigation, which is a very worrying sign.

If alarms are going to do their job then a response should be demanded but perhaps this ignoring of alarms suggest that on many vessels there is an alarm overload, too many

Modern electronic engines have alarms that cover a wide range of parameters and these may not only warn you that something is not right but they can slow or stop the engine automatically

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alarms, many of which are not particularly significant If an alarm is going to be of value then not only does it have to get your attention but it should offer a solution to the problem or at least indicate what a solution might be.

With a GPS failure most modern systems will keep the vessel on course by switching to dead reckoning plotting, using the previous course and speed to give an indication of where you might be. This is usually a time limited solution so you need to take over control and work out what to do and where to go. How many navigators know this and know what the time scale is? Electronic systems are notorious for the number of alarms fitted and you suspect that designers incorporate them simply because they can rather than because of any navigation significance.

Fire alarms are normally only fitted in the engine compartment because you cannot easily monitor that area visually. If that alarm sounds the temptation will be to rush and open up the compartment to see what has happened but you have to resist that temptation and trigger the automatic extinguishing system otherwise you will just be feeding the fire more oxygen and encouraging it to spread.

Again it would be helpful if, when the fire alarm sounds there was some indication of what action to take because you need all the help you can get when such an emergency strikes. The same could be said for many alarms throughout the boat. They should not only grab your attention but give you some options about what to do to solve the problem.

Modern electronic engines have alarms that cover a wide range of parameters and these may not only warn you that something is not right but they can slow or stop the engine automatically. Here, to a certain extent the skipper is out of

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8 A popular compact satellite dome antenna

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8 Low light TV cameras can enhance night-time navigation

the control loop and no matter what you do with the throttles the engine will not respond. It seems that the engine manufacturers are more interested in preserving their engines than preserving the boat. With many alarms they will hopefully tell you there is a problem, they might even tell you where the problem is but they don’t tell you how to fix it.

So alarms have a part to play and it is vital that the crew know and understand the alarms in all of the onboard equipment but it can be a major task getting to understand alarms because there can be so many. Most crews never get as far as ready the alarm pages in the handbook so they are left in the lurch when the alarm sounds and they might not even know how to stop the alarm let alone find out what it is about and most importantly what to do to cure the problem. As work and patrol boats become more complex so does the need to know and understand the alarm systems.

COMPASSES The basic compass is the one piece of navigation equipment that does not rely of a power supply to operate and so it is still a vital back up if the electrical system fails.

It is the ultimate get you home device and every boat needs one. With the electronics in full working order the compass has become almost redundant but apart from the heading information the compass can be quite useful for spatial orientation, getting a feel for what is happening around the vessel. The basic magnetic compass will present a full 360° picture at one glance but many steering 8 A colour electronic chart display of the type commonly used on workboats

The basic compass is the one piece of navigation equipment that does not rely of a power supply to operate and so it is still a vital back up if the electrical system fails

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compasses now only show a small section of the compass rose which is not so useful.

Like everything else on board, the compass has now gone electronic and whilst relying on the Earth’s magnetic field for direction information, this is sensed by a fluxgate and this allows the compass information to be presented in a variety of ways, even with a digital readout. The fluxgate compass is designed primarily for use as the reference for an autopilot and the readouts tend not to be designed for use as a bearing reference. The magnetic compass requires correction for both variation and deviation and whilst the variation is pretty well fixed for an area the deviation is boat related and can be found by ‘swinging’ the boat under the direction of a compass adjuster. It will vary with the heading and it is a simple correction to apply, plus or minus according to whether it is east or west. The deviation is the variable effect from the magnetic influence of the boat but rather than go through the complexity of having the compass ‘swung’ you should be able to get sufficient accuracy simply by comparing the compass readings with those from a hand bearing or remote compass that is held away from anything that might be magnetic. With a modern fluxgate magnetic type of compass you can correct it for deviation by simply turning the boat in a circle with the compass switched to calibrate and again these corrections can be applied automatically. You do need to decide whether you will operate the courses as true or compass courses but with the traditional magnetic compass you have no choice, it will show magnetic and you need to apply the corrections.

COMMUNICATIONS Communications are a vital part of workboat operations and whilst the ubiquitous marine band VHF is the standard requirement for every work and patrol boat there are now a number of further options available and the requirement for

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ELECTRONICS

most of these will depend on the area of operations. Whilst the marine VHF will be the standard for communications with other vessels and port and harbour it is an open channel and other vessels can listen in. This is done for the need for common channels for urgency and distress communications. The marine VHF radios will form an integral part of the GMDSS requirements that all workboats have to conform with in rules laid down by IMO to help safety at sea. For many working in inshore waters the mobile phone can provide more private communication with ranges perhaps up to 10 miles from the shore but coverage is not guaranteed and mobile phones are not part of the established communication requirements.

For those working further offshore and in more remote areas satellite systems such Iridium can provide worldwide communications but at a price and Internet and communication connections can also be obtained via Inmarsat with a wide variety of packages. Iridium is useful because it is a simple handheld unit but most satellite systems require a satellite dome to be installed on board.

For the future workboat communications may benefit from new multi-satellite systems being proposed that will provide fast Internet connections on a worldwide basis. For those who have requirements to transmit large quantities of data such as survey craft there are dedicated communication systems that can handle this and this leaves open the question of communications security.

The need for more robust communications technologies are primarily being driven by the big data requirements of smart ships such as unmanned boats, remote-controlled tugs, oceanographic exploration, research and training vessels. In recent years, technologies that connect ships to shore to convey real-time data have advanced significantly.

Next generation solutions are being developed to handle large volumes of information for intelligence-gathering and live video streaming, etc Emerging marine-specific software applications have also helped spur the digital transformation. With the advent of push-to-talk over cellular, crews can now tap powerful networks using walkie-talkie apps that live on smartphones or other mobile devices, and leverage specialized PTT wireless accessories to access them hands-free.

Connectivity is the key to the success of this transformation. Unlike the fast and reliable wireless data services on land, maritime has inherent limitations, including low throughput of legacy analog VHF radio systems, regulatory compliance concerns, and the IMO’s cyber security mandates. Implementing new networkcentric communications systems also faces challenges caused by lack of infrastructure, interoperability, spectrum, interference, and the diverse ocean environment.

In the interim, while the maritime world “turns the tide” toward digital, an integrated mix of communications technologies like high frequency (HF), VHF, satellite and cellular will continue to coexist. Meanwhile, more and more benefits of wireless communications are surfacing every day, from immediate access to information and more efficient operations, to better vessel performance, cost savings, and higher levels of safety. There is no excuse for not being in contact these days and the new age of communication will also enhance safety at sea where even personal beacons can communicate with satellites.

Amongst all this fast moving development is the need for radio installations on board to be licensed and for some of the crew who use them to have an appropriate operator’s certificate.

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WORKBOAT REVIEW | 55

DECK EQUIPMENT

CHAPTER NINE

DECK EQUIPMENT

8 A small hydraulic crane for cargo and man-overboard handling Right: A general purpose workboat with an hydraulic crane

For many workboats it is the deck equipment that provides their reason for existence. The boat itself is merely the platform on which the work takes places and this work is carried out by cranes, winches and items of specialised equipment. This equipment can operate on underwater projects and/or shore based structures and this is an expanding market with more and more of these specialised craft being developed.

CRANES Cranes feature on a wide variety of workboats and even on fast vessels such as wind farm support craft. There is an extensive range of standard cranes available that will meet most marine demands although many of these are based on cranes designed for fitting to trucks and land based equipment. The main difference in marine cranes compared with truck cranes is the level of resistance to corrosion which for marine cranes is vital in the corrosive marine environment. The two main categories are the knuckle boom crane where the various sections are hinged together and open out under hydraulic power and the telescopic crane where the sections telescope into each other and expand in

8 A pontoon workboat equipped with crane and winches for construction and mooring operations

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a straight line again under hydraulic power and a third option is a combination of these two technologies. In most cases the knuckle boom crane can be directly deck mounted because the sections of the crane allow it to form a curve as it is expanded in order to clear any deck level obstructions whereas the telescopic crane needs to be mounted on a raised base to provide the same level of clearance.

Cranes on workboats are fitted for a variety of uses from launching and recovering boats to handling cargo and lifting moorings plus their use in piling and construction operations. Hydraulic power is used almost universally for these cranes with perhaps a dedicated hydraulic power plant or the hydraulic power coming from a central unit which may be a main engine driven unit or a dedicated diesel driven power pack. Reliability is a vital element in crane operations at sea and there may be a back up hydraulic supply fitted when bearing in mind that a crane failure could leave the vessel moored to the lift with limited means of release.

We have been discussing fixed cranes here but the pontoon type of workboat with its open deck offers the possibility of accommodating mobile cranes. On larger construction craft the use of crawler type cranes in common but in the sizes of vessel covered by this book the space available for mobile cranes would be limited, in turn limiting the size of crane that could be accommodated. Concerns might also be raised about stability issues with the use of mobile cranes that can change position on the deck. Where mobile cranes might find application is for dredging, with a cranes fitted with a bucket grab could be used to convert a pontoon workboat into a dredger on a temporary basis, a solution that might work for a small harbour that cannot justify dedicated vessels for dredging. The spoil would be transferred from the grab into a hopper type vessel for dumping. Fixed cranes can also be adapted for this role The location of the crane will depend a great deal on its

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DECK EQUIPMENT

8 A simple davit system for handling a RIB tender

use. For boat launch and recovery it might be best for the crane to be located along the centre line to allow launch and recovery on either side and the same could apply to cargo handling equipment. For marine construction vessels the crane might be on the working side of the vessel but wherever the crane is located it will be necessary to have due regard to the stability of the vessel when the crane is at maximum extension or maximum load. Another factor to consider when cranes are operates at sea is the movement of the vessel in waves and here there can be a requirement for stabilising the load when it is being hoisted or lowered.

Where cranes are used for boat launching and recovery a secondary frame can be used to stabilize the movement of the boat when it is hanging from the crane hoist. Cranes also come under statutory requirements and these can include regular testing under load, regular inspections, particularly of the hoist wire and the training and certification of crane operators.

WINCHES Virtually every work and patrol boat will have a winch of some sort even if it is only the anchor winch. For many workboats a winch is essential for lifting moorings and winches are also used for connection to anchors when a workboat has to be positioned accurately and has wires connected to anchors. In many respects winches are like cranes in terms of their powering although winches have more flexibility for using electric power because hydraulic 8 A heavy duty hydraulic crane for handling moorings

A-FRAMES An A-frame provides an alternative type of lifting equipment that tends to be dedicated in is application. It comprises an A shaped frame that is hinged at the bottom of each leg and which can be adjusted in angle under the power of two hydraulic cylinders. It is usually found mounted close to the transom so that its centre lifting point can span the aft working deck as well as out over the transom. Its used tends to be restricted to survey and similar craft that carry unmanned vessels of some sort that are used for underwater operations, often in conjunction with divers. The A-frame provides a direct lift from the water onto the deck so that swinging can be minimised.

Modified versions of A-frames are used for handling specialised underwater sampling and handling other specialised equipment with the A-frame providing a simple basic lifting system for a variety of uses. It has always been surprising that the A-Frame has not been developed as a launch and recovery system for tenders as it would provide a simple means of transferring a tender from the aft deck into the water and if the tender was lifting up into a reception frame attached to the A-frame then it would be secured against movement when being transferred to its stowage.

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WORKBOAT REVIEW | 57

Credit: Goodchild Marine

DECK EQUIPMENT

8 A variety of deck equipment is vital to many workboat operations. Right: A casualty recovery system fitted to the transom of a pilot boat

cylinders do not form an integral part of the mechanism normally. So far as is known winches do not require the same level of training and qualification for operation either but they are rated for a certain level of maximum pull with possibly two ratings, one for the static pull when the winch is not actually operating and the other for the winding in pull when the winch is actually in use.

For tugs the towing winch can be a vital part of the equipment and there are dedicated units designed for this purpose that can automatically maintain a preset pull if desired. Whilst towing, conventional tugs will have a main winch for towing, push tugs use smaller winches to locate the tug at the rear of the tow. We are now seeing towing winches fitted to many SAR craft where they may have the option of towing a stricken vessel with towing winches making it a safer operation than just connecting tow ropes.

Specialised winches can maintain a steady pull by paying out and pulling in the wire/rope as required and the winch also provides the stowage for the tow line. To help extend the life of a tow line or indeed any line on a winch, a spooling system is a vital part of the machinery so that the wire or rope spools onto the winch in an orderly fashion.

SPUD POLES Spud poles are vertical poles usually attached to the corners of a pontoon workboat which can be lowered into the sea bed to provide a temporary mooring. The system is much quicker and easier that laying out anchors and is used by workboats that need to shift location at frequent

8 A twin davit system for the launch and recovery of a large tender

58 | WORKBOAT REVIEW

intervals. The poles can be simply raised or lowered at the press of a button. Their use is restricted to calm water operations with anchors taking their place offshore and because the raising and lowering mechanism does not actually provide the location means they can quickly be adjusted to tidal ranges either manually or automatically.

Two spud poles are generally used so that the workboat is not only located in position on the seabed but also in attitude, maintaining the same heading. Much will depend of the work being carried out but spud poles are a useful location tool for many workboats. Like cranes the stability of the vessel needs to be considered when spud poles are fitted as the can add a considerable weight high up in the vessel when retracted.

An extension of the use of spud poles is the lift boat and here three or four poles are fitted which can be raised or lowered and which, when resting on the sea bed can lift the whole vessel clear of the water to create a stable work platform for construction work. The size of these lift boats is generally outside the scope of this book but smaller sizes could offer an option for some operations.

DAVITS AND SLIPWAYS Davits are widely used for the launch and recovery of rescue boats and other craft that can come into the workboat category and which are carried on board mother ships. This is an expanding sector and here it is the boats that are carried on board rather than the ships themselves that are covered in this book. A wide variety of davits have been developed for boat launch and recovery and it pays to buy the boat and the davit from the same manufacturer so that the two match up closely. Launch and recovery from a ship at sea can be a challenging and high risk operation and the skills and techniques required are covered in my book Launch and Recovery of Boats from Ships published by the Nautical Institute. There are now full IOM requirements for the maintenance and servicing of these davits following a series of accidents and both boat crews and operators need to have gone on a course for this although such courses rarely replicate the real life conditions found in the open seas.

For the smaller craft covered in this book, the type of boats that will be launched and recovered are likely to be up to 8 metres in length. For this there are two main methods, davit and crane launch and slipway launch. Davit and crane launch is only really suitable for smaller tenders up to perhaps 6 metres so that the size of the equipment for launching can be contained. For this type of launching operation it should be remembered that the boat being

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DECK EQUIPMENT

8 An integral stern ramp tender launch and recovery system

A wide variety of davits have been developed for boat launch and recovery and it pays to buy the boat and the davit from the same manufacturer so that the two match up closely

‘‘

launched can be quite high so that the stability of the mother ship needs to be considered. The challenge with both davits and crane launches is to stop the boat swinging and rotating during the transit from deck to water and with smaller tenders this is usually done simply with ropes but with heavier tenders the davits are often fitted with restraining arms to limit the swinging. Restraining systems used with cranes have been developed but they are not widely used and the use of cranes for launch and recovery is quite limited although a crane can offer the ability to launch on either side and there is more flexibility with the stowage arrangements than there is with dedicated davits.

Slipway launch and recovery is a developing sector and is now used quite widely on patrol boats that need to carry boarding boats for boarding other vessels at sea. The slipway provides an expedient way to launch and recover the boat although it does take up a lot of space within the stern of the mother vessel and it also compromises the deck space. The viability of slipway launch and recovery will depend largely of how important the boarding boat is in the overall operation of the mother vessel.

The slipway may be a deep recess into the deck, usually with a transom door that can reduce the impact of following seas filling the slipway space. Obviously good drainage is required and the tender needs careful driving to enter the slot cleanly. The critical part of the operation as it is with both davit and crane launching is connecting the hoist wire to the boat and some automated systems have been developed for this. The German lifeboats have a chain system that operates in the keel slot so that the tender hull automatically engages with this and is hoisted clear of the water without human contact. Having to transfer the winch

wire connection manually can introduce risk to the operation whilst the boat needs to be held in the slipway under its own power until the connection is made.

Slipway systems are generally only suitable for use on vessels that maintain a steady draft because the height of the entry into the slot is quite critical. There are systems with an extending slipway that offer a bit more flexibility about the draft of the mother vessel but these add to the complication. If a slipway launch and recovery is going to be used and is going to work effectively it needs to be designed carefully to match both the mother vessel and the tender and to understand the conditions under which launch and recovery will take place. Slipway launch and recovery systems are being developed for handling small autonomous craft that can be carried to supplement the activities of mother craft and these are often seen using an extending type of slipway launch and recovery. These types of unmanned craft can be useful when surveys or searches have to be carried out in hazardous areas.

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8 Reliable anchoring systems can be a vital part of larger workboats

WORKBOAT REVIEW | 59

CREW COMFORT, SAFETY & SECURITY

CHAPTER TEN

CREW COMFORT SAFETY AND SECURITY

8 Full protective crew suits for cold weather operations

The crew is a vital component in any work or patrol boat and these days their welfare comes under considerable scrutiny to ensure that they can operate in a safe and secure environment. The operator of any workboat now has a ‘Duty of Care’ for the crew of their boats and translated loosely this means that the operator has to provide a working environment for the crew that minimises any risks, whether they are medical or physical as far as is reasonably possible. ‘Duty of Care’ is a very negotiable term as far as its legal aspects go and the operator’s responsibilities have to be balanced against getting the job done and not taking any unreasonable risks. This has to be achieved in boat operations where the weather and the operating conditions can vary from day to day and where assessment of the risks and the measures taken to mitigate them tend to be subjective rather than objective so that there are no hard and fast standards.

Any assessment will depend a great deal on the area of operations for the vessel. Harbour craft tend to have a fairly static environment at least as far as sea conditions are concerned so the requirements for safety and security on these craft can be compared to those required for many industrial operations on land. Compare this to the way in which a fast patrol boat might operate where the crew can be subject to considerable impacts as the boat attempts to maintain speed in waves and where boarding operations can present an additional risk area. In this sector there are many mixed views about safety and security standards

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with much of the safety being in the hands of the person driving the boat which makes it harder to set and to quantify the safety standards required and expected.

Boating is always going to be an area where safety and security are much harder to quantify than on land and with workboats and patrol boats often having to operate in challenging conditions it can be hard to make objective judgements. The aim is always to reduce accidents and to prevent any long term damage such as loss of hearing but with so much of the accident side of the equation being in the hands of the individual and the captain/skipper regulation cannot always come to the rescue. We are seeing an increase in the legislation that covers this sector, most of it aimed at creating a safe vessel, but there are so many variables that legislation can only go so far.

Legislation can only cover those aspects of the vessel and the operation that can be measured but with so many aspects of operations being unquantifiable, that term, Duty of Care, becomes the catch-all phase of legislation that covers everything else.

HARBOUR CRAFT SAFETY As we have said, on these craft it is largely a case of following the standards required for industrial operations.

Factors like non-skid surfaces, suitable handrails on stairs and handholds where required are the obvious ones but there could be extra demands such as marked snap-back areas around winches where there could be dangers if a wire or rope parts. Bulwarks have to be at set heights as far

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CREW COMFORT, SAFETY & SECURITY

8 A Hadrian clip on deck security system that is widely used on pilot boats. Far left: Many workboats now offer full air conditioned control stations where protective equipment is not required

as possible to offer protection and these add an extra burden particularly on smaller vessels where space can be at a premium. Where-ever there is moving machinery and on construction craft there could be quite a lot of this concentrated in a relatively small area then precautions are necessary and these need to be worked out for each individual vessel. A risk assessment that shows what the potential risks might be, the possibility of them occurring and steps that can be taken to mitigate the risk is an important part of assessing the risks and in most cases it can be a legal requirement. Such a document will not stop accidents but it can at least create an awareness of the potential risks.

Then there is the provision of facilities for relaxation such as a crew mess room. Much of this will depend on the type of vessel and the way it is being operated. Up in the wheelhouse the skipper would expect seating at the controls and it is to be hoped that there has been some measure of ergonomic design in the layout plus good visibility of the working areas and around the horizon. Noise levels are coming under increased scrutiny and keeping these down to acceptable levels can be a real challenge when the machinery such as the engines are working inside a metal box and the operations themselves such as pile driving can generate their own considerable noise. Ear protection has to be considered in many cases and hard hats and steel capped shoes can also be mandatory as well as possibly wearing lifejackets.

Smaller harbour craft such as those used for patrol and monitoring duties will vary greatly in shape and style but here the requirement will match those for other fast craft that operate out at sea such as safe secure seating, good handholds and good layout.

PASSENGER BOATS Much the same requirements apply to passenger boats both large and small with the added requirement that fare-paying passengers expect and should be provided with high levels of security and safety both as they move around the vessels and when seated. Handholds require special consideration bearing in mind that passengers may not have any familiarity with boats and so will be, in what to them is an alien environment. Provision may also have to be made for aged, disabled and infirm passengers. If the passenger boats are operating out in the open sea then even more care is needed with secure seating and possibly even seat belts. Here much of the safety and security can depend on the way that the boat is driven and a very conservative approach is required. Safe entry and exit to and from the boat must also be considered and this may vary a lot with the variations of the tide and shore facilities.

A different approach to safety is needed with the ‘Thrill

Ride’ type of boats where clients are taken out in a fast boat in waves to allow them the ‘thrill’ of travelling at speed in waves. Once again a conservative approach is needed when carrying inexperienced passengers. They need to be well briefed, they needed to be provided with secure handholds and they need to be monitored carefully so that anybody in distress can be quickly identified. Lifejackets are a must and protective clothing needs to be offered. There have been a number of accidents in these boats and the person driving the boat can tread a narrow line between giving the passengers a thrill but at the same time ensuring their safety. The authorities are taking a more pro-active role in these boats, both in the way that they are operated and in the way that they are fitted out but they can only go so far and it is the driver of the boat who ensures safety at the end of the day.

FAST PATROL BOATS With fast patrols boats, the ride can be lively, introducing some high shock loadings on the crew. There has been considerable research and investigation into shock mitigation and sprung seating is the main option to meet

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8 Lifejackets are essential wear for all on deck operations

WORKBOAT REVIEW | 61

CREW COMFORT, SAFETY & SECURITY

8 Sprung seating with safety harnesses on a Norwegian lifeboat.

Right: These crew sprung seats have adjustable back rests

the ‘duty of care’ requirements. It is possible to reduce shock loadings at source rather than take steps to reduce it in the boat design and this is combination of the way in which the boat is driven and the design of the boat.

The modern solution of adopting sprung seating can go some way to reducing the vertical impacts but can have a detrimental effect on the lateral movements that affect the crew. The seats add weight high up in the boat and also locate the crew in a higher position which raises the centre of gravity which in turn makes the boats less stable and more prone to sharp lateral movements and impacts. This can be accentuated by having outboard motors for propulsion where the centre of gravity will be considerably higher than with a corresponding inboard engine mounted low down in the hull. With sprung seating the occupants are moving up and down with the seat and this can make it more difficult to get the more subtle throttle control that is required for sensitive fast boat driving, demonstrating how solving one problem can make another worse.

Also the sprung seating only absorbs shock loading that are vertical or near vertical but a lot of these shock loadings are created transversely when the boat heels over in waves and the flat of the vee of the hull impacts with the waves.

Most of these transverse impacts are caused by overenthusiastic use of the steering and the aim should be to minimise the use of the steering wheel either by steering by autopilot or by just minimal use of the wheel to correct the course. It is hard to get helmsmen to just caress the steering wheel when it tends to be used as a handhold as well as for steering but the improvements can be considerable and again this is an area where a compromise solution is required. Fitting shock mitigating seating for the crew is a

8 Pilot transfer operations at night can be a very hazardous operation

62 | WORKBOAT REVIEW

visible and quantifiable method of meeting Duty of Care requirements whereas the way the boat is driven is not.

The design of the boat can help to minimise impacts with a deep vee for the hull and with RIBs, reducing the pressure in the tubes can make a significant difference and reduce the ‘bounce’ of the tube. Fitting sprung seating is a solution that tries to cure the problem inherent in the boat and the way it is driven but the best solution or at least a supplementary solution is to reduce the impacts at source.

The result of these various aspects of boat design and development is that whilst the seats may help to reduce the measured vertical impacts and reduce them to levels required by legislation, the increased potential for impacts and increased lateral movements can have a detrimental effect on the crew which can be accentuated by the general lack of support against lateral forces except by holding on tightly. Seat belts can also help to reduce the stress on the crew by reducing the need to hold on securely but they are not always acceptable by crews. This is a classic case of the application of the law of unintended consequences with the proposed solution actually making the situation worse. We are seeing some seat designs with a degree of lateral support for the crew which at least acknowledges that there is a problem but by going back to the basics of high speed boat design both the vertical and lateral impacts can be reduced considerably and sensitive driving techniques can also significantly reduce the impacts forces on fast boats.

Running at speed through the water it is important that the water has a smooth flow path to help give the boat a smooth ride. Any part of the hull that forces the water flow to change direction acutely will lead to the generation of impact forces. This phenomena can be found at the wide chines that are used to generate lift which helps to stabilise the hull. When the hull is upright on re-entry into the water these flat surfaces can cause impact and this will be accentuated if the hull is not fully upright on re-entry when the chine and the hull surfaces will form an inverted vee that will force the water to adopt a very sudden change of path.

Here the chine does not need to be a single flat surface but could be a stepped chine that would have the same surface area of a single chine but would generate lift on a gradual rather than a sudden basis and thus cushion the ride. For the bow to generate lift in following sea operations it is volume more than wide chines that are required and a hull with an accentuated flare at the bow will have a rapidly increasing buoyancy as it becomes submerged and at the same time reducing the need for substantial chines in the forward area to give a smoother ride.

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CREW COMFORT, SAFETY & SECURITY

The original concept of the RIB was for the inflatable tube to deform under wave impact and thus help to absorb the shock loadings of wave impact. The lower attachment of the tube to the hull can form an inverted vee when the boat is running in calm water and in waves this inverted vee can act like a chine and force the water to follow a torturous path to escape at the sides. The original RIB concept was that the tube would deform under this type wave impact and create a relatively smooth path for the water flow but on most modern RIBs where the tube is inflated hard the tube will not deform and thus higher impact forces are generated.

Worse still, a hard tube will generate ‘bounce’ so that not only will the tube create a sudden change in hull shape that is not wave kindly but it will also generate forces that can make the boat bounce from side to side generating considerable lateral forces. In a worse case scenario the boat can end of bouncing from side to side on the tubes and in one case with a race boat, the boat ended up by capsizing.

So with RIBs, a simple solution to reduce impacts is to

reduce the tube pressure but the design and location of the tubes can also influence the ride. Tapered tubes at the bow can reduce the impact potential here and still provide adequate buoyancy for following sea operations. Tubes mounted high above the waterline will have less influence on the ride but the hull will have to heel over considerably before their buoyancy becomes effective and they become more of a fender than a part of the hull variable geometry. It has been suggested that tubes inflated to a high pressure are required to protect the rigid hull during launch and recovery operations from a mother ship where the boat can swing against the ship’s side. However this should be solved by improving the launch and recovery system to prevent the impacts rather than using it as an excuse for high tube pressures and a rough ride.

A stepped hull can help to reduce pitching motions because the hull is riding on two of three longitudinal points rather than a single one. However you cannot use water jet propulsion with a stepped hull so this feature may be ruled out if water jets are considered to be an important

8 Head rests on seating can make life on board more relaxing in adverse conditions. Left: Sprung seating may not always be compatible with using the controls easily

8 Another view of the Hadrian security rail system on the foredeck of a pilot boat

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WORKBOAT REVIEW | 63

CREW COMFORT, SAFETY & SECURITY

8 The critical pilot transfer operation

8 The near vertical wheel is not always compatible with sprung seating for easy operation

operational requirement such as to facilitate beaching or when recovering casualties from the water is part of the operating scenario.

Flaps or interceptors can be used to improve the ride in head seas where they can be used to keep the bow down and reduce the pitching motions. This comes under the driving of the boat rather than the hull design but the manual adjustment of flaps is not always easy and operators might consider the use of fast acting automatic flaps or interceptors to improve the ride control in head seas.

Modifying the hull design to give the crew a softer ride and reduce the impacts can lead to a considerable improvement in the ride quality. This has to be mainly done at the design stage but on RIBs, considerable improvements to the ride quality can be achieved just by reducing the tube pressure. A pressure of 2 psi is about right rather than the 4 psi or more used on many modern designs. The boat may not look so pretty as wrinkles in the tubes may show up but it is a question of priorities.

If a driver is going to drive a fast boat sensitively and reduce the impact loadings then the controls need to be considered. So often a steering wheel is used more as a handhold than for steering because the helmsman is not securely located in the boat. Ideally a helmsman should the strapped in so that he has both hands free for the controls.

Recognising that this is not always practical partly through seat design and partly through the operational requirements, the seat should at least provide support both against impact and lateral forces.

The steering wheel should ideally have one ratio for open

64 | WORKBOAT REVIEW

sea use and one for slow speed manoeuvring. In the open sea a considerable movement of the wheel should provide only a small movement of the steering system so the excessive steering movements are eliminated. Excessive movements of the steering can be eliminated by using auto-pilot control for the steering so that course corrections are kept to a minimum so that the boat does not heel over.

Useful reductions in impact loadings can be achieved by minimising the use of the steering wheel although it is recognised that such steering control would not always be acceptable when travelling at speed. Coxswains should be encouraged to minimise steering wheel movements rather than use it in fierce attempts to maintain a set course. Attempts to use a motor cycle handlebar type of steering system in fast boats always leads to excessive steering corrections and a rough ride.

For the throttle, again this should be capable of sensitive adjustment and the popular single lever controls that embrace neutral and reverse restrict the important ahead arc of operation to just a small section of the possible movement.

This does not allow sensitive throttle adjustment and on fast boats the throttle should be separated from the gear operation so that the throttle movement can operates over a considerable to give sensitive control.

Flap or interceptor control when driving a fast boat is challenging because the driver only has two hands which will be engaged with the steering and throttles.

There is a lot to be said for using fast acting interceptors coupled to an automatic system and this combined with the use of the autopilot for steering can go a long way to reducing the impacts.

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CREW COMFORT, SAFETY & SECURITY

Modifying the hull design to give the crew a softer ride and reduce the impacts can lead to a considerable improvement in the ride quality

‘‘

To sum then fitting sprung seating appears to satisfy the Duty of Care requirement as far as authorities are concerned but equally good results can be achieved through sensitive boat design and driving. However the latter are not visible to the authorities that judge these things and so as a general rule sprung seating is now widely used to help smooth the ride. So the safety and comfort of the crew in a fast boat is a combination of factors but as far as the authorities are concerned the focus is likely to be on the seating rather than other factors.

NOISE AND VIBRATION LEVELS These are mainly industrial problems that have spilled over into boat operations and again as part of the Duty of Care an operator is required to minimise both noise and vibration. The two generally go hand in hand with the factors that produce noise generally also creating vibrations and because both of these factors can be measured there are levels set for workboat operations.

The main noise and vibration on board will almost certainly come from the engine compartment and here there are two remedies. One is to mount the engine(s) flexibly so that engine noise and vibration is not transmitted directly to the surrounding structures and the other is insulation which is now widely used to absorb noise.

Mounting the engines flexibly does pose problems because it means that all of the connections to the engine, cooling water, electrics, fuel supply and exhaust have to have flexible connections built in which obviously has an impact on reliability. Modern flexible connections can cope with this but there is also the factor of added cost but that is the penalty that has to be paid for reducing noise and vibration.

Hull noise through wave impacts can be a factor that adds to the noise levels and this is normally found in fast boats as they pound in waves. Once again insulation is used to help damp out this noise and keeping doors shut below decks can also help. There was a time when it became the norm for the whole superstructure to be flexibly mounted on some workboats in order to reduce noise and

vibration affecting the crew but the complications involved have taken this option out of the equation and it has been found that acceptable noise and vibration levels can be achieved by treating them at source.

For many boats that work on construction projects there can be noise and vibration from the machinery on deck but this tends to be temporary and the cure here is to use ear muffs at least to lower the noise levels. Hard hats and ear protection are now the normal wear for workboat crews carrying out this type of operation and this applies to crews both those working on deck and in the wheelhouse.

Whilst expertise and knowledge can help to predict noise and vibration levels at the design stage the measurements are taken once the vessel is completed and there may always be the requirement to add further damping after completion. This is largely a matter of first tracking down the source of the problem and then finding a solution, which is a job for the experts. One way to reduce both noise and vibration that is gaining traction is to use electric motors rather than diesels. This may not be a viable option for many workboat operations at present but it represents the future and the simple rotating part of the electric motor can significantly reduce both noise and vibration compared with that from a reciprocating engine. At present it is largely an option for harbour craft because of recharging requirements but there are also hybrid options.

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8 Pilot transfer even at deck level can still be hazardous

WORKBOAT REVIEW | 65

HARBOUR, DREDGING & CONSTRUCTION CRAFT

CHAPTER ELEVEN

HARBOUR, DREDGING AND CONSTRUCTION CRAFT

8 A compact harbour tug/workboat that can undertake a variety of harbour duties.

Right: A harbour tug that is also capable of sea-going operations

This chapter covers a wide range of vessel types from small agile harbour master launches to heavy duty construction craft but the common factor here is that they are generally operating in the protected waters of a harbour or a river. This means that seaworthiness is not such an important factor and speeds are generally slow although some small patrol and monitoring craft may achieve planing speeds in order to have the capability to catch offenders.

These smaller harbour craft may be operated by the police or the harbour master and in the past there have been customs and medical inspection craft. In smaller harbours that cater for leisure craft these craft may be based on a hulls such as the trihedral Boston Whaler type which provide a practical solution, combining a useful speed with stability and low wash. Being open boats they do create a hostile environment for the crew if they have to operate in the winter and where this is the case it is usual to find that larger vessels with an enclosed wheelhouse will be used. As much of their operational duty will involve going alongside other craft good fending is required and RIBs are often used for these roles. As always it is a balance between cost and operational requirements but with modern requirements for Duty of Care it is becoming common to find that an enclosed wheelhouse is now an important requirement.

One area where open boats are still used is for mooring launches that handle the ropes of large ships as they come alongside. This can be a dangerous area of operation working close under and around the ships as they come alongside and their use is dying out as modern tugs can handle ships right into their berths so that mooring ropes can be passed directly ashore. However there is an expansion of dock facilities in more remote and exposed areas such as oil and gas terminals with minimal connections to the shore where larger mooring launches are still required. These larger mooring launches tend to be

66 | WORKBOAT REVIEW

based on displacement hulls and in smaller harbours can also double up as a small tug perhaps for handling disabled craft and barges etc.

Smaller tugs come within the categories covered by this book and here we can see a dichotomy of ownerships with smaller harbours operating their own tugs because the work will not justify a commercial tug operation. A tug is still necessary for ship operations although here we are seeing changes as ships are coming more manoeuvrable so that the requirement for tugs is reduced. We are seeing this particularly with smaller cruise ships that are now visiting smaller harbours to widen the passenger experience and these are often fitted with azimuthing thrusters for propulsion to achieve excellent manoeuvrability and to reduce the cost of employing tugs. For larger harbours with the size of ships increasing and these becoming less manoeuvrable, more powerful and larger tugs are required so that the role of smaller tugs tends to be moving towards employment for dredging and construction work where they are required to handle un-powered hopper barges or pontoon floats.

The role of smaller tugs is being widened to keep them employed and we are seeing them used for operations such as seabed levelling where a plough is towed behind the tug to level out high spots in the seabed as a viable alternative to full scale dredging. Small harbour tugs can also be adapted to lift moorings for annual inspections of chains and with relatively small modifications to the layout of tugs they can be adapted to a variety of additional roles that can help to justify their costs. In the US small push tugs are widely used to handle the single barges that are made up into major tows which form a significant part of the US river transport system. Push knees on tugs are becoming more common in Europe as a way to use the tug that avoids the need for tow ropes and their potential dangers. Where rope handing mooring boats are still a requirement small tugs with a protective frame over the

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HARBOUR, DREDGING & CONSTRUCTION CRAFT

and so the vessels need gainful employment and adapting them for debris removal is one alternative with floating debris becoming a hot topic as this book was written.

Harbours are required to have plans and equipment to cope with oil pollution incidents or oil spills and most of this comprises booms to contain the spills and chemicals to help remove the oil. The plan is for this equipment to be

8 A harbour RIB workboat equipped for towing duties

Credit: Damen

superstructure can be adapted for the job to widen their role. The tug is still the ubiquitous workhorse of the small harbour with the design of tugs changing quite significantly to widen their employment.

Harbour tugs need to be compact because they may have to operate in very confined areas of water and it is not uncommon to find tugs of around 24 metres in length fitted with engines of 3-4000 hp. This power is coupled to azimuthing thrusters to provide excellent manoeuvrability with the tugs capable of operating in any chosen direction.

These tugs tend to be dedicated to ship handling rather than being multi-purpose craft.

Whilst major dredging operations are outside the scope of this book and are generally carried out by specialist companies, many smaller harbours will have a form of dredger to carry out maintenance dredging in order to maintain prescribed depths. In many cases these can be a form of earth moving equipment mounted on a pontoon type of vessel rather than a dedicated dredger which can be hard to justify in terms of cost and use. In particular small dredgers of this type might be used for maintenance dredging in marinas where a versatile and manoeuvrable vessel is required to cope with the tight spaces. However in addition to this type of versatile craft where the crane carrying the grab might also be adapted for lifting moorings there is a wide variety of small specialised dredgers of varying types that are small enough to be road

transportable that might be brought in for a particular job. Like so much of the workboat sector there are vessels that have been developed for a wide variety of specific roles but the trend is towards a more versatile approach where other craft can be adapted to the role or where dedicated dredgers can fulfil other roles such as coping with oil pollution, are required. In any assessment of dredging requirements for smaller harbours it is necessary to compare the necessity of dedicated units against adaptable equipment that can perform other duties.

It is much the same with oil pollution control equipment and debris removal vessels. Here again there is a considerable range of dedicated types of vessel but oil pollution requirements will only occur at random intervals

8 Operating tugs can be a challenging business.

Inset: An inland waterway push tug with elevating wheelhouse

deployable by harbour workboats rather than having dedicated vessels although the latter may be justifiable in larger harbours. However it is very likely that any oil pollution control vessel will need to be capable of other duties as well and one of these roles could be dredging. This cross fertilisation of roles is a bit like trying to create a Swiss Army knife, with the economics suggesting that if you can get one boat to do many of the jobs required in a smaller harbour then this could be a god solution. However as always when you try and adapt one boat to do many jobs it may not end up doing any of them well and effectively but there are boat builders who can offer a variety of versatile craft for harbour roles. Much will depend on the size of harbour involved with larger harbours having more resources to pay for and to justify dedicated

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WORKBOAT REVIEW | 67

HARBOUR, DREDGING & CONSTRUCTION CRAFT

8 A compact harbour dredger with associated workboat

vessel compared with smaller harbours.

When we come to look at construction craft we find that many of them are also trying to be suitable to carrying the wide range of construction jobs. These can range from pile and sheet steel driving to working with moorings and concrete construction, in fact all of the construction roles that you find on any construction site. Most of the pontoon types of construction craft are fitted with perhaps a crane and a winch on the deck as these have to be fully secured and installed and these can be supplemented by land based equipment as required. Portable concrete mixers and pile driving equipment are relatively easy to mount of the deck and the crane can be adapted for dredging and excavation work. Another type of portable tool is to mount cherry pickers on deck which can then be used to carry out bridge inspections. Basically the pontoon is used to create a work platform that can be adapted for a wide variety of jobs and they may be equipped with generators for a power supply and also mooring systems such as winches.

Pontoons can come in powered and un-powered versions but even the latter usually have some form of power if only for provide electrical or hydraulic power to equipment or electricity for lighting. The work of these pontoons vessels has to be carried out day and night in many cases to take advantage of tidal conditions. Powering these vessels whilst still maintaining a shallow draft is a challenge but the propellers are usually installed in tunnel recesses at the stern so that the pontoon can easily take the bottom if required. This type of flat bottom, squared off hull shape is not the most seaworthy concept and if the vessels are required to move from job to job by sea then they would normally have to wait for a weather window.

Typical of this new generation of multi-purpose construction craft is one developed in the US where the pontoon type hull has been developed to accommodate three engines and a triple screw propulsion system totalling 2200 hp within a draft of about 1.5 metres even though the propellers are 1.2 metres in diameter. On deck there are two winches, one for a towing wire and one for handling moorings plus a crane and at the bow there are retractable mooring knees for push towing, all this within a 17 metres overall length. It is perhaps the push towing roles that justifies the high power fitted to this vessel.

Apart from normal rope moorings these pontoon craft have two main options. One is to layout moorings attached to anchors in the seabed, a system that allows the position of the pontoon to be adjusted within the limits of the moorings as construction work progresses. The other is to use spud poles that are lowered into the seabed to hold the vessel in positions. In tidal conditions both need to be adjusted to match the changing sea levels and a further mooring option is the lift boat where the pontoon hull has three or four spud legs and machinery that allows the hull to be lifted out clear of the water to create a very stable construction platform although such lift boats are really outside the scope of this book as far as size in concerned.

Credit: Goodchild Marine

8 A river pilot boat with a ‘beak’ bow

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SAFETY AND SECURITY Safety and security have to be considered when operating most types of construction craft with the main risks being stability, ropes and wires under tension and people going overboard. For the latter this risk may often require that the constructor provides a safety boat, usually a small RIB that can patrol the adjacent waters to quickly recover any one overboard. Such safety boats are a feature at many construction sites with specialist operators providing vessels and crews for this job. Another safety requirement is that the vessels themselves have to be fitted with a rescue zone, a marked space in the bulwarks where there is a door and a ladder or Jason’s Cradle to facilitate rescuing people from the water. Safety markings are also used on the deck to indicate hazardous areas where wires or ropes might lead to winches or where crew should not stand.

These safety features can be found on most harbour craft such as dive and survey boats and of course it is now an almost universal requirement that anyone working on deck is required to wear a lifejacket and a hard hat and often steel capped shoes. The two latter requirements may

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HARBOUR, DREDGING & CONSTRUCTION CRAFT

appear to be un-seamanlike but it demonstrates the way the construction practices are moving from the shore to out on the water.

PROPULSION Diesel engines are still the primary source of power for harbour craft because of the often higher power requirements but also because of its flexibility and selfcontainment. However, there are concerns about both pollution and noise because these craft are operating in harbour areas and it would seem that electric power could be viable for many of these craft because of their close access to charging points, particularly for smaller craft like harbour patrol, survey and mooring launches. For construction vessels and tugs diesel power remains supreme although for tugs there have been moves towards hybrid systems where there is diesel power when maximum towing pull is required and electric power can be used when the tug is engaged in loitering time or lower power operation which can be a considerable proportion of modern tug operations.

A Belgian company is experimenting with the use of hydrogen as a fuel for a tug and the ‘Hydrotug’ is under construction where the ABC diesel engines will be capable of operating on hydrogen as the fuel but with the option of switching to diesel fuel when required. The hydrogen fuel will be stored under pressure in a bank of smaller cylinders rather than one large tank because this offers a reduced weight solution but with hydrogen, the storage of adequate fuel is still a problem to be solved. Operating a vessel on hydrogen does depend on having a refuelling station and this can be arranged but widespread use of hydrogen as a fuel will depend on the establishment of readily accessible refuelling stations which will probably limit its use to harbour craft at present.

8 A pontoon workboat working to support dredger moorings Left: Pontoon workboats has a limited sea-going ability

8 A pair of harbour tugs with a fire-fighting capability. Inset: dedicated workboat working on inland waterway weed clearing

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WORKBOAT REVIEW | 69

SEARCH & RESCUE OPERATIONS

CHAPTER TWELVE

SEARCH AND RESCUE OPERATIONS

8 A fast Norwegian lifeboat based on a double chine deep vee hull

Operating boats on search and rescue represents one of the most challenging areas for workboats mainly because of the wide range of operations that it can entail. The sector is dominated by voluntary organisations although in some countries there is government sponsorship or at least financial help and the boats employed in SAR can range from small RIBs up to large dedicated vessels. Although the sector is largely involved in saving lives at sea it can also involve fire-fighting and towage because using these techniques might be the best way to cope with a casualty. Fire-fighting is mainly a harbour operation as far as dedicated vessels are concerned and relates as much to property fires as well as vessel fires.

LIFEBOATS The dilemma facing the provision of search and rescue craft is that it is hard to predict where and when casualties will occur and they take place in a wide range of weather conditions. The traditional lifeboat was designed to operate in weather extremes because that was when ships and boats tended to get into trouble but that has changed over the years and today casualties occur in fine as well as bad weather and the time to reach a casualty can be a lot more critical. This has led to a complete re-design of lifeboat concepts with modern boats now being designed as all-weather lifeboats combined with having a planing speed capability. Virtually all lifeboat operations are now carried out by fast boats based on a modified deep vee hull and with a speed potential of at least 25 knots. For operating in extreme conditions, lifeboats need to be able to travel faster than the waves that they are operating in so that they can dictate their position in regard to the waves in following sea operations. This means that in offshore waves a minimum speed of 25 knots is required but now we are seeing lifeboats such as those used in Norway having speeds of 40 knots and a pioneering Italian lifeboat design

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is reaching speeds of 55 knots and combining this with self-righting and an all weather capability.

With almost all modern lifeboat designs being based on deep vee hulls which have been clearly shown to be effective in extreme sea conditions and a good compromise for higher speeds, there appears to be little requirement for design innovation. However, working with the Dutch lifeboat people, the research centre Marin and Dutch shipbuilder Damen, a new hull concept has been developed.

This is the Axe Bow lifeboat which features a vertical stem connected to a sharp right angle at its bottom where it turns into the keel. A heavy chine rises at the bow and generates lift to help planing and trials have shown this concept to be very effective in rough seas. Whether it is more effective that a conventional deep vee hull is hard to judge because it can be challenging to carry out comparison trials and one wonders how much of the effectiveness of an alternative design comes from the competence of the person driving it.

This combination has been a long time developing and essentially modern lifeboats are not very much different in hull design from many patrol and other fast boat designs.

Where they do differ is that the lifeboats are designed not to fail because any failure in extreme conditions could be disastrous. The engineering and scantlings are only the best available and the hulls are sub-divided so that the boats can stay afloat and hopefully operational even after damage. One part of the boat where this is not done and which could be a vital flaw is in the engine compartments where almost universally, both engines are in the same compartments so an engine fire or hull damage in this area could quickly immobilise the boat. To install the engines in separate compartments can be quite a design challenge but it does seem to be an essential requirement for the potential safety of SAR craft. These planing lifeboats depend on having the engines fully operational for a large measure of their safety as they have transferred much of the safety of the craft from the design of the vessel into the hands of the person driving it.

8 A RIB developed as an airport rescue craft with high capacity liferafts to cope with large numbers of casualties

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SEARCH & RESCUE OPERATIONS

Most lifeboats these days are self-righting so that if they do capsize they will automatically right themselves again.

This is one more safety feature in lifeboat design that is now being adopted for some other workboat applications.

Making a lifeboat self-righting can be quite a design challenge which is why the sub-division of the engine compartment seems to be a design omission to extend the safety of the boats. It is all a case of judgement on the part of the authorities who develop the design criteria of the lifeboat where for instance the British RNLI insist that all of their lifeboats are self-righting because there have been capsizes in the past whereas the Norwegian lifeboats are not self-righting because they have never had a capsize.

The trend these days is to make lifeboats inherently self-righting so that basically they are unstable when they capsize so that they will automatically return upright from the capsize. This is achieved largely through designing enough buoyancy into the superstructure to create that instability when upside-down. It sounds a simple solution but it introduces a lot of other factors that have to be considered such as making the crew self-righting as well as the boat. A boat capsizing can introduce some quite violent movements as the boat rolls and unless the crew are fully secured in seats then they could suffer considerable injury as the boat rolls through 360°. The same applies to any equipment inside the superstructure which also has to be secured. Then the self-righting depends on having the superstructure sealed so that water cannot enter during the capsize and the crew have a vital role in ensuring this.

Finally the engines have to cut out during the capsize to prevent damage to the engines if the oil in the sump hits the pistons if the engines are still turning.

Not only is it a considerable design challenge to engineer all these requirements without compromising the capability of the lifeboat but consideration needs to be given to the conditions under which a capsize may occur. This is likely to be when the boat is going too slow in heavy following seas

and the coxswain does not have sufficient control. Then there is always the risk that when there is one capsize it could be quickly followed by another before the crew manage to regain control of the boat and drive out of the situation. This means that the crew have a vital role to play in the safety of these fast planing lifeboats so that considerable training and experience is necessary to operate them safely in the extreme conditions that they are designed for. The introduction of self-righting may relieve the conscience of the designers of these boats on the basis that they have done everything possible to ensure the boat’s safety but maybe this can lead the crew into a false sense of security.

In a new development the Swedish Sea Rescue service has taken into service what is though to be the first lifeboat with a hybrid propulsion system. This is really an attempt to reduce emissions rather than any advance in life-saving capability but the reasoning behind this development is to provide an alternative propulsion system when the lifeboat in standing by a casualty or otherwise engaged in low speed operations when the low power electric propulsion can be brought into operation.

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8 A RIB rescue boat with a self-righting superstructure

8 Lifeboat testing in heavy surf

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SEARCH & RESCUE OPERATIONS

8 A basic rescue boat similar to those required to be carried on some ships Right: A fast rescue boat coming alongside a casualty at night

INSHORE LIFEBOATS Supplementing these all-weather lifeboats are fleets of inshore lifeboats and rescue boats which are mainly based on RIB designs. These range from the small sailing club rescue boats that escort fleets of sailing dinghies up to significant sized RIBs complete with wheelhouses. RIB designs are also being used for all-weather lifeboats and first ever RIBs were originally developed by this rescue boat role. The RIB has a number of advantages for search and rescue work, notable of which is the high level of stability that the inflatable tube gives to the boat, useful when recovering survivors from the water. The tube also acts as a fender when going alongside at sea and as we have seen in the section on hull design the inflatable tube can improve the seaworthiness of the boat if the inflation pressure in lowered to allow the tube to deform and help to absorb shock loadings.

The smaller RIBs used for inshore operations have the ability to operate close inshore even amongst rocks and they can be beached making them able to cope with a wide variety of casualties. Indeed they are so versatile that in many cases they are taking over the role of the all-weather lifeboat and there is certainly a blurring of the lines between the role of the inshore lifeboats and the all-weather lifeboats.

The seaworthiness of RIBs allows them to be driven hard when out on rescue missions and to enable the crews to survive the impacts and pounding, sprung seating is now widely used. Good handholds are also required and many of these inshore rescue boats are fitted with self-righting systems. Because there is no superstructure to help with self-righting and the tubes tend to provide good stability when the boat is inverted, the self-righting systems comprise an inflatable bag attached to a frame at the stern.

Inflation is triggered by a pull cord and when the bag inflates the boat will turn the right way up. At with the inherent self-righting lifeboats there are several factors that have to be considered when designing and operating these self-righting systems.

Firstly, these are open boats so the crew will be in the water when the boat capsizes and there is always the possibility that one or more may be trapped under the boat.

To reduce the chance of injury when being the boat is being righted it is essential that all the crew are seen to be clear of the boat before the inflation is triggered. Then, like the larger boats, the engines have to be modified to survive the self-righting movements. If the engines are diesels then similar cut-out systems to those used on the larger boats are used whilst with outboards cut outs are required along with systems to seal inlets and outlets from the engine.

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Self-righting for these inshore boats is further complicated by the fact that adding the self-righting air bag and its frame above the boat reduces the stability of the boat in the first place and so makes them potentially more prone to capsize. Because they can be operating in surf and other inshore areas where breaking waves are more likely these inshore lifeboats can be more exposed to capsize risks and there is always the risk that a first capsize will be followed by more before the crew can get back onboard they offer no guarantee of survival. Once again so much of the safety of the boat is in the hands of the person driving it and this is why there needs to be a strong focus on the controls and the layout and design of the wheelhouse of console.

CONTROLS We have looked at control in Chapter 6 but nowhere are the factors involved in controlling the boat more important than on search and rescue operations. As we have said, so much of the safety and capability of these craft is in the hands of the person driving them and the ability to operate the controls and the response that the engine and propulsion offer is vital to success. We are seeing a higher reliance on electronic systems for control such as electronic steering and throttles and in some cases, the removal of the steering wheel altogether and replacing it with tiller control.

Automated systems such as the autopilot which can be a great asset in lively sea conditions can help to maintain a stable heading whilst automated trim systems can both improve the ride of the boat in waves as well as relieving the workload on the coxswain. Joystick control can be a real bonus when rescue craft are operating alongside a casualty but for rescue operations this form of control does require a powerful response.

With all the crews now being seated in dedicated positions in the wheelhouse of lifeboats there are moves to share the workload amongst the crew. For instance there

Automated systems such as the autopilot which can be a great asset in lively sea conditions can help to maintain a stable heading whilst automated trim systems can both improve the ride of the boat in waves as well as relieving the workload on the coxswain

‘‘

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SEARCH & RESCUE OPERATIONS

may be a dedicated navigation station where one crewman works with the electronic chart systems whilst communications can be handled by a third station. This type of workload sharing does require trust and capability amongst the crew but it can leave the coxswain free to focus on the handling of the boat and to consider the tactical situation such as the requirements of a search operation and how to usefully employ other vessels that may be assisting in a search operation. Lifeboats may take over the role of on-scene commander is a search and rescue operation and here the coxswain may even relinquish control of the boat to a crewman to focus on this role.

Each lifeboat organisation will have its own way of operating and much will depend of the competence of the crew. The Norwegian people operate their sophisticated lifeboats with just a three-man full time crew. They are highly trained in all types of rescue work including diving, medical and recovery operations but the coxswain has a heavy workload with not only controlling the boat but he also has the controls of the towing winch and other deck equipment at his station as well as having to handling radio and navigation work. Good visibility from the helm is an essential requirement if such systems are going to work and indeed should be a factor for all lifeboat wheelhouses even when there is a flybridge control station fitted to give better visibility. Such control positions can be a great feature when carrying out search missions.

Others organisation like the British RNLI rely heavily on volunteer crews who can never have the same level of training which can put a heavy load on the coxswain who is usually full time. With such a system it can be more challenging to build up the teamwork required because the availability of dedicated crew members cannot be guaranteed. This brings us to the challenge of operating lifeboats and rescue boats and in many cases these boats can lie idle for a month or more, waiting for the call to come.

This is a considerable waste of resources in terms of the high cost of providing a lifeboat service and there are arguments in favour of giving lifeboats a secondary role such as possibly being used as a pilot boat or a patrol boat of some type. This would have the benefit of having a full time crew who could become highly proficient in operating their boats because they are using them all the time and

could lead to considerable cost savings without having to compromise the design of the lifeboat. Another possibility is that lifeboats and rescue boats could be available for other emergency work such as coping with oil pollution, fire fighting or debris recovery.

8 A French lifeboat carry a small daughter rescue boat for working inshore

RECOVERING CASUALTIES Recovering casualties from the water is an essential part of search and rescue operations but it can be quite a challenging task. Medical advice is that casualties should be recovered in a horizontal position as far as possible but if they are just being hauled aboard from the water that can be virtually impossible. Even when the recovery is from a low freeboard rescue RIB the casualty will almost certainly be hauled over the side head up and even that can be a heavy lift for two people, one on each side because you are lifting quite a quantity of water as well as the casualty themselves so in the interests of expediency the aim should be to get the casualty out of the water as soon as possible.

One of the best solutions once the casualty is alongside is to push them down and then do the recovery on the bounce as they spring up from the dunking but casualties do not tend to be very cooperative to having this done.

8 A proposed Icelandic all-weather lifeboat design

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WORKBOAT REVIEW | 73

SEARCH & RESCUE OPERATIONS

8 A combined rescue boat and ambulance boat for operation in Scandinavia

There are a number of dedicated recovery systems to aid recovery in the horizontal position. These can be particularly valuable when trying to recover casualties from vessels with a higher freeboard and essentially they entail getting a flexible platform under the casualty and then by pulling on the outer ropes, rolling the casualty up and on board. The challenge with all of these systems is taking the first step and getting the tail end of the flexible platform under the casualty. Workboats with a working after deck are required to have bulwark doors to aid the recovery of casualties from the water and most modern lifeboat designs have a section of the deck that is lower or a side platform to aid casualty recovery from the water. There are also systems that can help to bring a casualty alongside and in some cases get a sling around their body so that they can be lifted on board with a davit.

TOWING Towing a casualty back into harbour is a common feature of rescue operations and despite the fact that the primary role of the lifeboat may be saving lives, bringing the boat back as well can be the expedient way of effecting the rescue. For effective towing a strong mooring post is a feature of the aft deck as is the ability to lower railings where necessary. Some lifeboats have a dedicated towing winch fitted which can be a useful feature where the vessel is being operated with a limited crew as it allows the winch to be operated from the helm in the wheelhouse whilst the rest of the crew is engaged in connecting the tow.

Towing out in the open sea can put a heavy stress on the tow line and the equipment and a non-stretch rope is best so that the rope does not snatch as the strain comes on it.

Wire rope is another possibility but it does not float of course so it can be heavy to handle particularly when being hauled on board a casualty where tired and weakened crew might be involved. When connecting a tow there is always the risk of getting a rope around the propeller and one of the snags with joystick control is that you can never be quite sure what propellers and thrusters will be used when you move the lever so it is not easy to isolate the propellers if a rope gets in the water.

FIRE Many lifeboats are fitted with a fire monitor because rescue work at sea can involve having to cope with fire which is the reason for the vessel calling for help. Coping with a fire on board a casualty can be quite a challenge and the priority should always be to get the people on board transferred to a place of safety and then the fire can be tackled. Whilst lifeboats can have fire-fighting equipment for this secondary role most major harbours will have a dedicated fireboat that is equipped to carrying out fire

8 Carrying out recovery operations in shallow waters

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SEARCH & RESCUE OPERATIONS

fighting duties both on shoreside properties as well as ships and boats in the harbour. These fireboats are like a reversal of roles with lifeboats where the primary duty is to save lives whilst the fire boats are equipped primarily to fight fires. Trying to combine the two roles is not very successful as one role could compromise the other because a dedicated fire boat needs considerable amount of dedicated equipment. This can range from tanks to hold foam for fighting oil fires through to high placed remote controlled fire monitors that can aim powerful jets of water down onto a fire and water mist sprays that can protect the fire boat itself when near to a fire. Shallow draft and a low profile may be other requirements to allow access to various parts of a harbour. Plans have been developed for autonomous fire-fighting vessels and these can take some of the risk to human life out of the equation. We will look at this in more detail in Chapter 15.

MULTI-ROLL EMERGENCY VESSELS Providing vessels for emergency roles can be an expensive business if each role requires a dedicated vessel so there is a lot to be said for trying to integrate several roles into one vessel. Many would argue that only by developing dedicated vessels for each, search and rescue, fire-fighting, oil pollution, ambulance etc. can the most effective solution be found. Much will depend on the resources available and technically there can be limits on what roles can be combined whilst still retaining an effective vessel for each role. Where savings might be made is to combine emergency roles with more routine roles such as pilot boats and lifeboats where one role does not compromise the other or at least only to an acceptable degree. What is sure is that many emergency vessels are very under utilised which can be challenging in trying to motivate their crews and emergency vessels of one sort or another tend to require highly trained crews if they are to be effective. Perhaps that is a good reason to look carefully at the use of automated vessels in some of these emergency roles which would not only take crew risks out of the equation but which could

also provide a more effective vessel because risks to the crews do not have to be considered.

AUTONOMOUS EMERGENCY CRAFT With the crew often being the weak part of any emergency vessel operation there is considerable interest in whether emergency vessels could be effective without a crew on board. This aspect of SAR will be looked at in much more detail in Chapter 15.

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8 Demonstrating the capabilities of modern lifeboats, this one towing a large disabled ship

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PILOT & PATROL CRAFT

CHAPTER THIRTEEN

PILOT AND PATROL CRAFT

8 A fast pilot boat demonstrates its capabilities

A great deal of what was covered in the last chapter on search and rescue craft also applies to the roles covered in this chapter, both of which are demanding but with the difference that the use of the boats is much more planned with hopefully little or no emergency situations to deal with. This means that there should be no demand to operate in more extreme conditions and no requirement for the boats to be capable of survival in extremes. Having said that, pilot boat operations can be challenging and demand both sound boats and skilled crews. Patrol craft may have to operate some way offshore which requires good autonomy and for some operations, have to carry out boarding at sea so both types of craft require vessels designed for the job with a lot of attention to detail.

PILOT BOATS The concept of pilot boats has changed over the years with only just a few cruising pilots ships left in operation, transferring their pilots to ships by boats launched from davits. From there the concept of fast pilot boats ferrying pilots out from the harbour was developed first with semi-displacement hulls and now with fast craft based largely on the deep-vee concept. For a conservative approach to pilotage operations this represents a major change and has opened up a whole new market area.

The demands for pilot boats will vary from harbour to harbour depending on the distance outside the harbour where the boarding takes place and the sea conditions that

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can be encountered both on the way out and in the boarding areas. Shipping these days is less tolerant of delays to their schedules which can make heavy demands on pilot board operations and the conditions in which they can take place. The actual boarding operation or disembarking is the critical area when the boat is alongside the ship and the pilot has to transfer from boat to ship or vice versa. This is a high risk operation and is what one pilot boat builder described as ‘Controlled Collisions’ and little has changed in the basic process over the years except in detail. The boats are equipped with well placed handrails on the foredeck, fendering has improved considerably and the regulations regarding the quality and installation of the pilot ladders has improved.

Still there are risks involved, the main one being the pilot missing his/her footing or handhold during the transfer and either falling back onto the boat or worse, falling between the boat and the ship. There is a requirement for the pilot boat to be able to recover someone from the water quickly and it is for this purpose that we are seeing powered personal hoists fitted at the transom of many pilot boats.

This is not the ideal solution because the recovery has to take place close to the propellers and other systems are like the man overboard recovery systems found on many workboats, using slings and davits. The risk of a pilot falling in the water is not high because the consequences can be so serious so careful steps are taken to ensure safety but falling between boat and ship could entail serious injury which is likely to handicap recovery efforts.

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PILOT & PATROL CRAFT

There are many schools of thought about the fendering requirements for pilot boats. There is no argument about the need for fendering because the constant going alongside ships in the open sea requires some form of cushioning to absorb the shock loads and rubber or plastic fendering is the normal system in use. Because the pilot boats can be rubbing alongside in both a fore and aft direction as well as an up and down direction, designing fendering that will cope with this twin movement direction is not easy. One problem with rubber fendering is that it has a high resistance to movement but the pilot boats needs to be able to slide along the ship’s hull in all directions so there is a move towards some form of heavy duty plastic rather than tactile rubber. The consensus about fendering appears to be to fit vertical type strips that are angle forward at the top combined with a deck edge fender with the latter taking the main impact.

When it comes to fendering it would be thought that the inflatable tube of a RIB would be perfect for use on a pilot boat but in general there has been a reluctance to use RIBs as pilot boats although this is changing. Currently the RIBs that are used as pilot boats tend to be smaller RIBs operating out of smaller ports where they can provide an economical solution but there are several reasons for this reluctance to use RIBs. One of these is that RIB tubes tend to be inflated to higher pressures than that of earlier designs and this means that when coming alongside the tubes ‘bounce’ off the hull of the ship and it can be challenging to hold them alongside because they ‘bounce’ away. Then with the inflatable tube forming the extreme edge of the boat, the pilot has to stand on this inflatable tube to step onto the pilot ladder and this does not give a very secure footing. Finally we must add in the conservative nature of the pilot boat sector which shows a distinct reluctance to change from the tried and test solutions. It took years for pilot boat to switch to faster designs from the old proven displacement hulls and now we are seeing the same with RIBs but their time may come once the demanding requirements of pilotage are fully understood and RIBs designed accordingly.

Features that we see that are mainly unique to pilot boats are the sliding rails around the side and forward decks that allow both pilot and crew to clip on when moving around the deck. Because of the boarding operations, the normal rails or bulwarks around the deck cannot be fitted and in addition to these slides, there is usually a system of rails mounted inboard on the forward that allow crew and pilot to hold on during transfers.

Another feature is the visibility from the wheelhouse.

Because these boats are generally operating alongside high sided ships there are windows in the roof of the wheelhouse to ensure good visibility. In addition the superstructure is set well in from the side of the hull so that it will not make contact if the boat rolls when alongside. Pilot boats tend to be a specialised type of workboat but their sea-going qualities and competent crews can make them effective rescue craft as suggested in the last chapter.

For pilotage operations that can required a long journey our from harbour to the boarding point, which is mainly carried out in ports based on rivers, there is a requirement to ensure that the pilot arrives at the ship in good order, both to be fit enough to climb the boarding ladder and to be alert for the often long hours of pilotage. This has led to the fitting of special high comfort and security seating for the pilots and to fitting automatic trim systems to help reduce the vessel motions. In the US a considerable fleet of pilot boats now have these automatic trim systems and they are reported as offering useful benefits in terms of ride comfort.

Pilot boats tend to favour diesel engines coupled to conventional propulsion systems and water jets are rarely used. However a new development is the use of electric propulsion. Pilots operating on the River Thames have what is claimed to be the first hybrid pilot boat, one where the main propulsion is diesel engines but it is possible to switch to electric power when idling or low speed cruising. In the US a full electric pilot boat is under development where the main propulsion is electric motors with diesel engines as a back up or for longer journeys. This boat is aimed at a pilotage where the voyage out to the pilot station is 8 to 10

8 A SWATH pilot boat provides a stable platform alongside a ship

8 Fendering is an important part of pilot boat design. Far left: A large pilot boat design for offshore operations

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8 A high speed patrol boat designed for hot climates. Inset: A patrol boat with an Axe Bow that is claimed to have good seagoing characteristics

miles each way and a speed of 18 knots is planned for this 40 footer. It sounds like a logical development and one where many other pilot operations could follow suit in the interests of reducing both emissions and noise.

Whilst we are talking here mainly about the type of dedicated pilot boats that are used at major ports and harbours, smaller harbours may have a wide variety of boats that are employed on pilotage duties. Much will depend on availability but maintaining a dedicated pilot vessel can be an expensive operation and for small ports where there may be a requirement for pilotage perhaps just two or three times a week then the harbour masters launch may double up as the pilot boat just as the harbour master may double up as the pilot. Also when a pilot boat is out of commission on its annual overhaul there has to be some form of stand in vessel for the job and a local tug or mooring launch may fill this role.

PATROL BOATS Patrol boats embrace a wide variety of vessels both large and small that carry out a wide variety of duties. On the one hand there are fishery protection vessels that are out there to enforce fishing regulations whilst on the other there are military craft of varying sizes that can actually engage in warfare and where high performance might be at a premium. In between are boats designed for operations

such as customs and immigration and police, and perhaps the major operations for patrol boats are those carried out by coast guard organisations. Added to these stand alone roles there can be smaller patrol boats that are carried on board mother ships that can operate further offshore and which are launched to carry out boarding operations.

Where the type of operation demands a larger vessel, perhaps one over 15 metres in length for extended patrol duties and such a vessel is less suitable for going alongside in boarding operations then it may carry a small tender for boarding purposes. Launching and recovering such a tender can be a challenge on this size of vessel and rather than use a davit-type launch it is now becoming common to introduce a stern ramp into the design that allows quick and safer launch and recovery. Such systems are now well proven with even lifeboats using them but they do take up a lot of the aft section of the hull and the deck area and they do need to be carefully engineered if they are to operate successfully and safely. The tender would normally be a type of RIB and there have to be compromises between having a tender of adequate size and finding space for the launch and recovery ramp on the mother patrol vessel.

This patrol boat sector employs a wide spectrum of boat designs and these days almost all of the boats used are planing boats based on deep-vee hulls. For those patrol boats that are operating independently they can be

8 A Dutch law enforcement patrol boat with its daughter boat for boarding

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Defining a speed requirement for a patrol boat is never easy.

At the one end of the spectrum are the high performance interceptors that are mainly used by the military where speeds can range up to 70 knots whilst at the other end there can be patrol boats that do a leisurely 20 knots

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required to spend long hours at sea and so like the pilot boats, there has to be a strong focus on comfort and security for the crews. It is now the norm to find these boats fitted with sprung seating for all the crew and with these fitted with seat belts. Interceptors coupled to automatic trim systems are used to reduce the vessel motions at sea as they are for pilot boats and in addition these is often the need to have facilities for food and drink preparation as well as overnight accommodation.

Seasickness can be a problem with many patrol boat operations and having good visibility for all the crew can be a help in reducing its impact. There are also seasickness monitors that record the frequency of strength of vessel motions and impacts and these can be a useful guide to skippers that to a certain extent can predict the onset of sea sickness and alert the skipper to take possible alterations in course and speed to reduce vessel motions.

Where boats are designed for boarding operations at sea, the maximum size for these boats would probably be around 15 metres with any larger sizes leading to the generation of high impact loadings when alongside in a seaway. Many of these patrol boats have to find a compromise in size between the impacts alongside and the performance in rough seas. This can be challenging and the introduction of RIBs for many patrol duties has partially solved this problem but as said earlier the cushioning effect of the RIB tube has to be balanced against the ‘bounce’ effect when trying to go alongside at sea. The other factor to be considered is that none of the trim systems that might reduce vessel motions will be effective when at very slow speed alongside except perhaps the gyro stabilisers that are claimed to offer both high and low speed stabilisation.

Because they often spend considerable hours at sea on patrol it is likely that many patrol boats will be called upon to deal with casualties at sea which can widen the requirement for casualty recovery systems and some expertise amongst the crew. This casualty requirements is likely to be more that the normal requirements for vessels at sea to offer help in any emergency situation and the same goes for other factors that they may be called on to deal with such as oil pollution or simply escorting damaged vessels. Just being at sea can open up a wide range of potential emergencies and the best solution for dealing with these is to have a sound boat matched to an experienced crew.

It is likely that almost all of the patrol boats operating

around the world will be equipped with two engines but this may not always be the best solution. For many patrol boats there is likely to be a mix of both high and low speed operations when on patrol and equipping patrol boats with some form of loitering capability can be effective. With modern hybrid designs this could mean having an electric motor built into the system that would offer slow speed operations under electric power only with the electric supply coming either from a battery bank or having just a generator running. Another alternative would be to have a triple engine installation where the boat can operate on just the central engine when loitering.

Finding engine solutions is quite easy but matching them to an effective propulsion system can be challenging because you want a system that does not add drag when operating at speed. Water jets can be a good solution here because of their ability to operate effectively at a wide range of loadings and to offer minimum drag when not in use.

Defining a speed requirement for a patrol boat is never easy. At the one end of the spectrum are the high performance interceptors that are mainly used by the military where speeds can range up to 70 knots whilst at the other end there can be patrol boats that do a leisurely 20 knots. The speed requirements will be largely determined by the role of the boat and an assessment is likely to include the potential speeds of the vessels being

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8 A compact patrol boat designed for coastal waters enforcement Centre: A typical fast patrol boat designed for law enforcement

8 A patrol boat of conventional design developed for operating in the waters off Monaco

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Credit: Goodchild Marine

PILOT & PATROL CRAFT

Credit: Safehaven Marine

8 A pilot boat coming alongside for pilot transfer

8 Testing a new pilot boat to the limits in rough seas of Ireland

monitored and the waters being patrolled. For instance if a patrol boat is engaged in fishery protection that it will be mainly dealing with fishing boats based on displacement hulls operating at slow speed but there are some such as potters that can operate at higher speed of 20-25 knots.

Then the element of surprise also has to be considered with fishing boats reporting the presence of a fishery protection boat in the area to alert the others. Having higher speeds can allow the element of surprise inspections to be made with much more flexibility so the solution might be found with a fast patrol boat that can operate effectively and

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economically at lower speeds. The element of surprise can come into other patrol boat operations so that the potential for higher speeds can always be useful but that has to be balanced against the cost of higher speeds, particularly in terms of capital costs. It can be a delicate balancing act.

We tend to look at patrol boats as being based on monohulls but there are also possibilities for using catamarans and other multihulls. These multihulls may not have the rough sea capability of monohulls but then it would be rare for many patrol boat activities to be carried out in rough conditions. A catamaran offers a large deck

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PILOT & PATROL CRAFT

area and in moderate conditions it can provide a stable platform and they have been used for some specialised applications such as ambulance boats and police boats where the conditions that they have to cope with may be more moderate. It is the same with trimarans where the rough sea capability may be a benefit but trimarans are perhaps not a suitable vessel for going alongside at sea and they tend to be used in larger sizes where boarding is done with a tender.

There is such a wide range of designs out there for this sector of the market that it can require considerable research to find the right vessel for the job. Speed and seaworthiness will often be major factor in the design and modern developments are now allowing these two requirements to be combined in a single vessel as witness many modern lifeboat designs. Other detail requirements can influence the choice but the monohull, either in conventional or RIB versions is still the main solution.

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PASSENGER & WIND FARM VESSELS

CHAPTER FOURTEEN

PASSENGER AND WIND FARM VESSELS

8 A wave-piercing wind farm vessel with an escape vent for water trapped in the tunnels

Passenger carrying is a challenging area of workboat operations mainly because you are carrying a perishable cargo and one that will not suffer excess noise and movement. In addition there is a range of additional safety requirements and regulations that have to be met and speed can become an important aspect of the vessels involved. A wide variety of designs have been developed to cater for passenger carrying and this sector provides one of the most innovative areas of workboat design. Passenger carrying vessels in the sizes covered in this book can range from water taxis, ferries that cross harbours in calm waters, river ferries and so called ‘Thrill Rides’ out to the latest challenge which is taking technicians out to wind farm sites. Carrying passengers brings extra responsibilities to bear with the object of providing a safe passage and this in turn has lead to increased legislation and safety requirements. Each time there is an accident it can lead to an upgrade in the rules and regulations and this is a challenging sector both to build boats for and to operate them.

There is a trend towards exploiting the potential of water transport in harbours and rivers as it is seen to been a ‘Green’ alternative to road transport but it is becoming increasingly regulated in the interests of safety. Once again the Duty of Care comes into the equation and whilst most harbour and river ferries operate in calm conditions they are carrying passengers with little or no experience of the water. One of the key areas is in the boarding and exit areas where there can be many trip and other hazards and operators these days are required to make a detailed risk assessment. In some cases there is a requirement to make a

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safety broadcast in order to brief passengers about the safety procedures but many ferry crossings are very short so that these briefings are not required. The regulation of safety on small ferries is an area that is still developing and like so many aspects of marine safety the regulations tend to be reactive rather than proactive.

There are quite strict requirements for survival equipment on passenger carrying vessels, even for smaller ones but like most safety requirements these tend to be restricted to those factors that can be either quantified or forecast. Fire, collisions and machinery and hull failures are probably the main risks but because these vessels operate mainly in waters where there are other vessels nearby it is assumed that help will be quickly available in the event of a problem.

Items such as lifejackets, lifebuoys, liferafts and fire-fighting equipment can add considerably to the cost of a ferry operation and there will also be a requirement for a competent and qualified crew.

River and harbour ferries come in a wide variety of types and sizes. At the bottom of the scale there are water taxis that operate like land taxis and these can range from the beautiful varnished wood water taxis found in Venice to the advanced hydrofoil assisted Sea Bubble that is operating on the River Seine. In between there are more functional craft capable of carrying perhaps 6 to 8 people and the main criteria in these designs is a low wash and a good speed potential. Because they do not carry more than 12 passengers, these smaller taxi boats do not come under the more strict safety regulations of larger ferries but operators can tread a narrow line between speeding customers to their destinations and keeping the operations safe

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PASSENGER & WIND FARM VESSELS

particularly when operating at night. A big hazard for these smaller craft in many areas is debris in the water to which smaller boats can be vulnerable and craft riding on foils can be particularly exposed to this danger. Propeller propelled boats can also be vulnerable and water jet propulsion can be the system of choice to avoid this type of debris damage.

For ferries that cross rivers and harbours speed is not generally an important factor because of the shortness of the journey. However there is a growing trend to operate ferries along rivers, calling at dedicated stops, rather like a bus service and here speed can be important. For this type of operation planing monohulls will probably generate too much wash and the catamaran with its long slim hulls tends to be the preferred option. A catamaran with it large deck area also offers better passenger accommodation. Again water jet propulsion is the preferred option to minimise floating debris damage. The speed potential of these ferries can be in the region of 30 knots to provide a viable service and this speed in crowded waters demands a high calibre of crew to operate them safely, particularly at night.

ELECTRIC POWER Most ferry and water taxi operations operate in cities and because pollution is a concern there is a strong movement to use electric power rather than diesel but speed and electric power are not currently happy partners. Certainly there are many electric ferries coming into operation but at present it can be challenging to operate a fast ferry under electric power so electric ferries tend to be restricted to those ferries on short routes across rivers and harbours.

The need for regular changing is a big consideration and quick charging systems that can be connected at each terminal and allow a boost during passenger turn round are starting to be introduced. Converting ferries to operate under electric power is not a simple operation and there is also the safety aspects to consider when battery banks store a lot of power and new stringent safety features to reduce the chance of fire and/explosion are required. For excursion vessels that may operate a regular service but tend to operate at slower speeds, operation under electrical power can be an option and in Paris a fleet of these vessels that operate a regular service along the Seine are being converted to hybrid operation. The hybrid system allows the vessels to operate under electric power when there is power in the batteries but under diesel power at other times. It is estimated that the cost of this conversion is just 20% of the cost of new hybrid vessels which makes conversion a very viable option when the time comes for a refit.

The use of electric power is being expanded to ferry operations though and here there are two alternatives. One is to use solar power to supplement charging from the shore and this can work when the ferry operation is short such as across a river. One such operation is being trialled in France where it is being considered as an alternative to building a foot bridge across the river with the ferry operating at just 7 knots. The other possibility is the development of rapid charging systems that can be automatically connected when the ferry enters its terminal berth. Such systems are being developed and are becoming viable and could become the norm for any harbour ferry operations. In Norway electric ferries are being used extensively already, using such charging systems but these are larger car carrying ferries that operate across the fjords as a part of the road system in this challenging transport country.

Electric power is being used more widely in excursion vessels that carry passengers around a harbour or along a river. Here speed is not a requirement and the vessels can often be fitted with a large expanse of solar panels to help the recharging of the batteries. Generally more time is spent alongside as well and with a low speed requirement the electrical power requirements are more manageable. As many of these craft also operate in pollution sensitive areas this type of passenger vessel is leading the way with electric propulsion and the relatively quiet operation is another bonus. There is no doubt that electric ferries will be the future and they will present a considerable challenge to designers and to operators to develop the required infrastructure.

8 A SWATH wind farm vessel in operation

8 A catamaran passenger vessel designed for low emission inland operations

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8 A low profile passenger boat design for operations on Amsterdam’s canals

UNMANNED FERRIES Another area being explored for passenger operations such as ferries is to use unmanned vessels. There can be challenges for this type of operation such as how to limit numbers of passengers and how to control them but this should be possible with control from the shore. Automatic docking systems are now available and by using a vee berth where the ferry simply enters a vee into the terminal, docking can be simplified and no mooring ropes are required if the engines are kept running ahead to keep the ferry in place. Whilst this is an area being explored the rules and regulations relating to passenger vessels might restrict the implementation of such operations.

8 A Norwegian passenger boat with a bow loading ramp

THRILL RIDES One area of passengers carrying that is far removed from thoughts of electric propulsion is the so-called ‘Thrill Ride’ sector. Employing mainly large RIBs these boats are the modern equivalent of the ‘trips round the bay’ boats of the

1950’s - 60’s. The concept treads a narrow line between excitement for the passengers and their safety and there have been a number of accidents where passengers have been injured either through overenthusiastic driving, failure to assess conditions or passengers not holding on securely or following instructions. It can be a challenge for inexperienced passengers to cope with the rigours of high speed and many of these boats are not fitted with adequate seating and handholds. It requires constant monitoring of the passengers to ensure that they are comfortable with the ride of the boat they are often told to hold up their hand if they are not coping. That assumes that they have a hand free and do not require both hands to hold on with. For a thrill ride boat to be effective and relatively safe they require much more thought to be put into passenger security and one of the main problems is that the skipper does not know that he is driving too hard until one of the passengers complains or is hurt and then it is too late. The authorities are not comfortable with this type of operation but it appears to be a major challenge as to how to limit these operations without banning them altogether although there has been a significant reduction in injury accidents recently suggesting that operators are moderating their thrill tactics. These boats show how there can be a narrow line between safe and unsafe operations and you only know you are crossing that line when something goes wrong.

WIND FARM TRANSFER VESSELS A relatively new sector for passenger carrying has been developed in the requirement to get technicians out to the wind farm turbines that are springing up around many coastlines. For a long time there has been a demand for crew and technician transfers out to offshore oil installations and in relatively benign sea condition areas this has been done by crew-boats with the transfer to the rig or platform carried out by means of a basket lift. The alternative of course is helicopter transfers but neither of these methods is viable systems to use with unmanned

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8 The ultimate thrill ride down narrow gorges in New Zealand in water jet propelled RIBs

wind farm turbines. The solution that has been developed demonstrates just how a workboat problem can be solved by thinking outside the box.

Initially most of the transfers were done at the early wind farms that were located close to shore and the boats used were adapted monohulls. In these areas the sea conditions that had to be contended with were probably waves of 1 to 1.5 metres high and the journeys were relatively short. There are two main problems involved in this crew transfer operation, one ensuring that the technicians being transferred arrived in a suitable condition to be able to make the transfer and carry out the required work. The other was

the actual transfer itself from the boat to the turbine and the system developed meant that the CTV would put its bow up to the landing place on the turbine tower where the technicians could transfer onto a ladder. This transfer system has been developed into a relatively safe operation with the CTV’s having a squared off bow at deck level so it can butt up against the turbine landing and in some cases a shock absorbing system has been fitted to this bow area to help absorb the impacts and extend the potential range of conditions in which transfers can be made. On the turbine tower the ladder was located and recessed between two steel tubes to give protection to the person making the

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could reduce both pitching and rolling but of course these were only effective when underway at speed and did not contribute to stability when stopped at the turbine.

As the installation of turbines has moved further offshore, the demands to reduce the transit times has increased and more stable vessels are being sought this has led to the developments of a variety of new hull design concepts. Indeed it could be said that the wind farm vessel sector is now the pioneering sector of the workboat market although the basic catamaran hull still forms the workhorse of the sector. This work on new developments could have an important spin off in other sectors of the workboat market where there might be financial benefits in looking at proven new design concepts as a better solution for challenging operations at sea.

8 Passenger boats come in all shapes and sizes, many specially adapted to local requirements

8 A typical wind farm transfer vessel based on a catamaran hull with high deck clearance

transfer. It was pioneering work that has transformed the ability to transfer personnel at sea and this bow-on transfer is being used on some ships for transfer operations.

Those early monohulls were replaced by catamarans which were better for the particular requirements where transfers to the turbines could only take place in waves less than 2 to 2.5 metres depending on the wave direction and the vessel involved and these were the size of weaves in which the catamaran could perform well. This matching of the vessel capabilities to the transfer limitations is what has dictated the design of CTVs and the selection of catamarans as the primary vessel of choice. In waves much higher that around 3 metres the wave crests would start to impact on the underside of the cross deck of a catamaran and this would have required a reduction in speed. So the performance of the catamaran and the suitability of the transfer conditions were pretty much closely matched. In addition the catamaran offered a better stability when making the transfer and the fine bows of the catamaran hull were less prone to vertical movements when against the turbine tower landing.

So the catamaran became the vessel of choice for this passenger carry role and modern versions are equipped with comfortable and shock absorbing seating for the technicians in order to allow them to arrive at the turbine in good condition. Most boats were capable of speeds of around 25 knots which was adequate for the distances involved from shore to turbine in this second generation type of operation where the turbines were located up to 50 miles offshore. In order to reduce the vessel motions and to reduce the onset of seasickness some of these wind farm vessels were fitted with automatic interceptor systems that

As the installation of turbines has moved further offshore, the demands to reduce the transit times has increased and more stable vessels are being sought this has led to the developments of a variety of new hull design concepts

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NEW CONCEPTS There are always demands to extend the capabilities of this type of transfer operation to make them more financially viable and this has led to new concepts being developed.

More sophisticated designs might be more expensive but if the operation period can be extended in adverse conditions then this extra expense can be justified. There are two factors involved here, one to provide a comfortable ride out to the turbine towers and one to carry out the actual transfer but with the establishment of turbines further offshore there is also the question of speed in order to reduce the transit times. Another factor is the possibility of having accommodation on board so that the CTV does not have to return to shore each day so we are seeing considerable changes as the wind farms move further offshore.

The wave piercer hulls developed in Australia as the basis for large fast ferries use long slim side hulls to support the weight of the craft under normal running conditions with these slim side hulls offering very little response to the passing waves so you get a level ride. Between them is a deep central hull that under normal running is clear of the water but which provides additional buoyancy when waves get higher. This gives these wave piercers a more gentle cut off point when the waves get larger that is the case with normal catamarans. One of the problems with this concept is that in larger waves this centre hull splits the waves and this diverts the water up into the inverted vee above where it does not find an easy escape route and so certainly on smaller wave piercer designs you can find slamming occurring in larger waves.

Designer Juan Moreno found a solution for this by incorporating large vent holes moulded into the upper section of the side hulls which gives this diverted water an escape route and helps to reduce this slamming potential.

This concept has been used on some wind farm vessels in an attempt to provide a more comfortable ride on extended voyages in lively sea conditions. With catamaran designs, designers have found various solutions to try and soften the ride in adverse conditions but it is my belief that when a hull diverts water in some way you must always provide that water with an easy escape route so that it does not impact on the hull and this modified wave piercer concept could be one solution.

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SWATH and SWASH designs have also been tried where the main buoyancy for the hull is provided by torpedo shaped hulls underwater. In this way the buoyancy is largely isolated from being affected by wave motions and a more stable ride is promised. However the SWATH and SWASH concepts initially did not translate easily into smaller sizes partly because the concept requires a good clearance for the upper cross deck structure and because the ‘torpedoes’ have to be large enough to accommodate the engines. A SWATH is like a catamaran with two side hulls whilst a SWASH has a single main buoyancy ‘torpedo’ and slim side hulls to give stability.

Ad Hoc Design has been a pioneering the design of SWATH CTV’s and these have operated successfully with claims that the conditions in which transfers are viable being extended up to waves in excess of 3 metres. The benefit of the SWATH is that it provides a stable platform both when under way and when stopped alongside the turbine tower but the improved capabilities have to be balanced against higher costs of constructing the vessel and the limited speed capabilities of the SWATH. Two of the latest concepts to be developed for CTV operations are based on SWASH designs. These have already been proven by Danish operator World Marine Offshore, an operator that is known for its focus on high specification vessels with superior seakeeping characteristics. The Inertia PM5 design is an improved version of the company’s current SWASH designs and demonstrates how the design of CTV’s is a developing process where experience is fed back into future designs.

The latest designs have been developed with an emphasis on seakeeping, stability and 24/7 operation in mind in order to extend the operational window.

The Inertia PM5 vessels can transport 24 passengers in business class seats or alternatively accommodate 12 passengers in single cabins. The design will enable passengers and crew to remain offshore for up to 14 days and to carry out transfer in waves up to 2.5 metres high.

The service speed in 25 knots and a full automatic trim system is supplemented by a hydrofoil that can be lowered to generate up to 7 tonnes of lift and reduce hull pitching.

Even the propulsion is advanced with five water jets, one in each side hull and three in the centre hull. This gives enormous flexibility and is claimed to lead to significant fuel savings with the some of the engines being shut down when operating at the tower. The possibility of electric

propulsion has also been incorporated into the design.

This application of multiple engines rather than the more conventional twin engine installation can also be a viable alternative when a shallow draft is required. This feature has been exploited on some of the US crew boats that service the inshore rigs and platforms in the Gulf of Mexico. These vessels often operate from ports with a limited depth of water so a shallow draft was required and by splitting the propulsion between four or five units smaller propellers could be used and the draft reduced. One operator also used water jet propulsion with five engines, an installation that allowed the vessel to operate comfortable of the chosen number of engines depending on the speed requirement.

8 An alternative crew transfer vessel with forward superstructure Left: A crew transfer vessel for wind farm operations

HYBRID CTV’S A new design of CTV is claimed to be the World’s first the world’s first hybrid surface effect crew transfer vessel that will be used to service turbines off the Dutch coast. It is

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8 The scale of the crew transfer operation

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8 A small passenger vessel for offshore operations based on a RIB hull

claimed that the vessel will be able to handle transfers in 2m wave height and during transit there will be a significant decrease in fuel consumption and CO2 emissions. Power comes from 1,600 kW of diesel engines with electric power boosting this figure when required combined with the capability of operating on just battery power when at the turbine and in harbours. It is claimed this will reduce main engine use by up to 50%.

The Hybrid SES CTV has a 24 passenger capacity and the hull comprises a catamaran hull with the area between the hulls closed, by flexible reinforced rubber skirts. Fans blow air into this enclosed space, providing the air cushion that can support up to 80% of the vessel weight with a consequent reduce in hull resistance. It is claimed that the air cushion can also act as a shock absorber in waves, reducing hull motions

The remaining 20% is supported by hull buoyancy. This allows for higher vessel speed because the hull resistance is significantly decreased. It also reduces motion owing to less wave contact. In addition, the air cushion acts as a large shock absorber, improving the seakeeping and reducing seasickness. The hybrid propulsion can be used to boost the speed or to allow the vessel to operate on just battery power at slower speeds. This not only gives a greener footprint for the vessel but should reduce fuel consumption and at the same time allow higher transit speeds and a more comfortable ride.

OPERATIONAL LIMITATIONS One of the more interesting aspects of wind farm operations is that the limiting factor of the mission is the ability to transfer the technicians to the turbine towers. There is no

8 A crew transfer vessel design to operate from a mother ship

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PASSENGER & WIND FARM VESSELS

point in taking them out to the site if transfers cannot be made so that this transfer limitation tends to dictate the conditions in which the vessels might have to operate on the voyages to and from the wind farm. Because these weather conditions are not too onerous, probably waves up to a maximum of 3 metres this is what governs the sea-going capability of the vessels and there is no real requirement to be able to operation in severe sea conditions. It is thought that this is one of the main reasons why firstly, catamarans are widely used and secondly why designers and operators can be a bit more adventurous. The catamaran has rough weather limitations which are mainly related to the waves impacting on the underside of the cross deck but with the transfer conditions posing the wave height limits this cross deck limitation is not a severe problem.

It has always been a challenge to put operational limitations on passenger carrying vessels but in the interests of safety there is always this requirement particularly for smaller vessels. At the end of the day it is up to the operator or the skipper to make the final judgment and you only know you have got it right when it doesn’t go wrong. Passengers are a sensitive cargo and the margins between success and failure can be quite small because of the wide variety of capabilities between passengers of all ages and capabilities. The crew transfer vessels used by the

wind farm operators are in something of a special situation here because the ‘passengers’ will be generally fit and active but mainly because it is the ability to make the transfer that will be the limiting factor in the operations.

Because transfers can only take place in moderate conditions, the passage to and from the turbines will also take place in moderate conditions which can have a considerable influence on the design of the vessels.

Passenger carrying vessels are an area of the workboat sector that has invited some interesting developments, particularly pioneering work on the development of hybrid and pure electric propulsion. This has been particularly the case in the wind farm service sector where new concepts have been developed to meet the high demands of these operations. Here the emphasis on design has been to produce craft that can get a difficult job done and now it is switching to expand the operating window as the wind farms are being installed further offshore. These are pioneering operations and like the oil industry before it the operational requirements have produced new solutions.

With wind farms now being developed worldwide this European experience is being marketed internationally and the concepts that have been developed could start to revolutionise operations in other sectors of the workboat market, particularly in the patrol boat sector.

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AUTONOMOUS WORKBOATS

CHAPTER FIFTEEN

AUTONOMOUS WORKBOATS

8 An autonomous RIB workboat prototype

The weak point in many work and patrol boat operations is the human. Having people on board to operate the boat means that it is necessary to provide for their safety and security, to provide facilities perhaps for food and toilets and to ensure that the controlling interface works.

It can add up to a lot of extra complication and at the same time it can restrict the operation of the boat in the interests of the safety of the crew. So take the human out of the equation and it becomes possible to have a much more capable boat, one that is not restricted by human weaknesses.

The use of autonomous workboats is increasing and whilst these may be tentative steps into this new world the benefits can be considerable particularly when it comes to emergency craft and some other operations such as survey work. Unmanned operations may be restricted by rules and regulations that favour having a human crew but the climate is changing and the considerable benefits of autonomous workboats is staring to get traction.

SURVEY OPERATIONS Apart from military operations, this is where autonomous operations started. Survey craft often depend on covering the widest swathe of the ocean as far as possible with their soundings and sampling and modern electronic systems have enhanced this coverage but there are limits. So why not have an unmanned survey craft operating in parallel with the manned survey vessel to extend the coverage of the survey on each sweep? This was the motive behind this type of development and it can now be extended to having multiple unmanned craft working in tandem with the mother

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vessel. Perhaps the only limitation in numbers might be the ability of the mother vessel to launch and recover the drones.

This is a developing area and the Unmanned Surface Vessels (USV’s) that can carry out survey operations were first based on conventional craft but have now been extended to specialist designs that are more compact and which can be launched and recovered much more easily.

Because there is no need to provide for human control these dedicated USV’s can be considerably simplified with the design focussed on the survey and transmission equipment, the latter being required to transmit the data back to the mother vessel.

To demonstrate the emergence of the role of automated vessels for a wide variety of survey operations, Ocean Infinity has plans for a fleet of 15 vessels that can operate autonomously either by carrying out direct surveys from equipment carried on board and deployed through a moonpool or transmitting through the hull, or acting as the carrier and launcher for individual USVs that can roam from the mother ship. At the time of writing there is little information about these vessels but they appear to be around 20 metres long and capable of being equipped with a variety of equipment. Control would be by satellite communication links from the shore allowing the vessels to operate well offshore but at present there are no firm rules and regulations for offshore vessels operating in unmanned mode in the open seas. Satellite links for the control of USVs opens up the possibility of these craft operating far from shore which may be a considerable benefit for the offshore oil and gas industry and the wind farm sector.

Taking this development a stage further it then becomes logical to think about having survey USV’s operating on their own to reduce the cost and complication of the mother vessel. This can add considerably to the complication of the USV because not only is it required to have additional endurance but the recovered data has be to be transmitted over a longer range and the vessel has to be equipped with electronic systems that can undertake navigation and collision avoidance. This may be too much of a challenge for survey operations in deeper and more exposed waters but it can work for inshore waters, particularly those close inshore where the water may be too shallow for

8 A proposed autonomous cargo ship for operation in Europe

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AUTONOMOUS WORKBOATS

8 A proposed survey vessel design to operate autonomously

conventional craft to operate and where the operation of the craft can be controlled from the shore. Small USV’s that can be manhandled into the water and which can operate in very shallow water depths are now being used for survey operations and they are usually based on a catamaran hull and often with electric propulsion which is much easier to control remotely.

Unmanned survey operations are now being widely used and not only can it provide access to challenging areas of operation but it can also provide a solution for harbour surveys where the USV can be operated within line of sight so that the challenge of collision avoidance is removed from the equation.

USV’s AS FIREBOATS The use of unmanned vessels for emergency operations can offer considerable benefits largely because emergency vessels can often be required to operate close to their limits and with humans on board those limits have to be restricted. Take the human out of the equation and it is possible that many emergency vessels could be more effective. It seems likely that the first use of a USV for dealing with emergencies will be as a fire boat where an unmanned vessel would be able to get closer to the source of the fire without putting the crew at risk.

No only could an unmanned fireboat be more effective but it could also be cheaper with no requirement for a wheelhouse or crew facilities. It would simply be a platform with propulsion on which to mount the fire monitors.

Because it could be possible to get closer to the source of a fire then it might have to be built from better fire tolerant materials. Obviously communications would be a major factor in the design and control and this might pose a problem trying to establish effective links to the control station with what might be sensitive radio equipment.

Several design teams have developed what look like to be viable unmanned fire boats and because they can be tightly controlled and would operate mainly in harbour areas this could be the place where unmanned craft start to be used for emergency roles.

survey area can be extended. The challenge with a USV operating on a rescue mission would entail adding features such as a system for recovering casualties from the water and a system capable of connecting a tow. Cameras would be required to give a visual assessment of the casualty situation but this is current technology. These are all possible developments as the experience with USV operations expands and once again the use of a USV for search and rescue can take some of the risk out of the operation and also possible speed up the operation as the USV could be sent to sea immediately on receipt of the call rather than have to wait for a crew to turn up. The main problem with developing a USV search and rescue craft is likely to be an operational one because it would challenge so many of the current systems many of which are operated by volunteers.

One area where USV for rescue could be pioneered is for a rescue craft to be carried on board ships. Currently if a ship is called upon to effect a rescue out at sea the main solutions are to park the ship alongside the casualty and to try and lift the survivors up to deck level or to launch a lifeboat which is far from being the ideal craft for the job as they are designed just to make a one way trip and the crews often have little or no experience.

An unmanned rescue boat would take a lot of the risk out of the operation. Like a shore based rescue boat there would be a requirement for a casualty recovery system as

8 Recovering a survey drone onto an autonomous RIB

USV’s FOR EMERGENCY OPERATIONS Certainly on search operations a USV could extend the search area considerably much in the same way that a

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8 A compact autonomous rescue drone

well as a tow connector and for the return to the ship there would be a need for a system that would allow the boat to be automatically connected to the hoist for recovery. All of these requirements have been developed and it is really the current rules and regulations that are slowing implementation of such a craft. For the crew of the ship, the control of such a rescue boat would be no more challenging that operating a computer game so it is likely that there would be adequate skills on board amongst the younger crew, something that cannot be said the systems currently used for launching and recovering the ship’s lifeboats.

Autonomous craft could have a role in carrying out searches in hazardous areas such as when there is a major pollution event either in the water or in the air. In Norway unmanned large RIBs have been equipped with an automatic launch and recovery system that allows the unmanned craft to deploy a smaller unmanned craft that can greatly expand the areas that can be covered. Whilst not falling within the category of autonomous craft, the use of aerial drones is being expanded into the search and rescue role both as a way of greatly expanding the area that can be searched from the air and also as a potential method of transferring lines to a casualty. A small USV has been developed with electric power that can be launched from a beach to go to the aid of a swimmer in trouble with the drone being capable of carrying the survivor back to shore.

Many of these operations are still in their infancy but there will almost certainly be an expanding role for unmanned craft in search and rescue and other emergency operations.

MILITARY There have been several military USVs that have been developed mainly for use in minesweeping operations where there could be a risk to the crews of manned boats.

However we are now seeing a widening of military

applications into areas such as harbour patrolling and even as fast interceptors. For many military applications if you take the human out of the equation then the boat can be much more effective because human risk factors do not have to be considered.

Most navies are now using USV’s, mainly still on a trial basis and an example of this is a 40 foot version being used by the US Navy for harbour patrol duties. Controlled from the shore this boat has the ability to intercept and even fire guns at suspicious craft which adds a new dimension to the operation. Fast interceptor USVs could be loaded with explosives and used to attack hostile vessels and there are possibilities to use USV’s for a variety of patrol and interception duties although this will of course be limited to non-boarding interceptions in contrast to the type of boarding operations carried out by say, fisheries protection operations.

Patrolling harbours seems to be one of the more obvious operations that could be carried out by USV’s with the possibility of detecting vessels on the surface and divers and underwater craft as well. USV’s could offer a considerable saving in manpower and probably be more effective that manned patrols because there is no requirement to consider the limitations of human operations.

Patrolling harbours seems to be one of the more obvious operations that could be carried out

by USV’s with the possibility of detecting vessels on the surface and divers and underwater craft as well

‘‘

USV’s AS TUGS This is an interesting area for development but tugs directly under the control of the pilot or captain of a ship being berthed could open up possibilities. For an unmanned tug in this role in reality it becomes little more that a thruster directing power as required. However the thrust can only be applied in one direction because there is little possibility of connecting a tow line within current technology although line transfer systems are being developed. Most normal tugs are used or equipped for a variety of roles such as fire-fighting and oil pollution duties in addition to their normal towing role and whilst an unmanned tug could work well as a fire fighting unit other roles that require a rope tow line connection may be out of reach within the limits of current technology. However having said that, once

8 A recovery system for bring drones back on board. Far right: An autonomous survey vessel

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AUTONOMOUS WORKBOATS

an unmanned tug is accepted as a reality then it could open up developments that could widen its role.

Robert Allen Design has developed an unmanned tug design. Powered by a pair of 550 kW diesels coupled to Voith Schneider propulsion units they claim to have solved the problem of passing a tow line across by including an articulated hydraulic crane type unit on deck that can pass a tow line to a ship without human intervention. The same articulated arm could also be the mounting point for a fire monitor. This TOWBot concept is still at the design stage and awaiting approvals from various authorities but the question now is whether the market and operators are ready to implement this type of concept.

Another idea for connecting a towline from an unmanned tug is the use of drones that could carry a light line to the ship which then in turn could be used to transfer the towing line. Such a system is indicative of the possible solutions that are being developed to make the unmanned tug a reality.

IMPLEMENTATION There could be a wide requirement for unmanned workboats and patrol boats not only because they offer a potential saving in costs but also because they could be potentially safer. The technology is already there to meet the demand but there are two main problems towards their

implementation. The first is that the current rules and regulation that are not written to accommodate unmanned vessel operating away from a mother ship or from the shore. Even the Colregs make no allowances for unmanned craft and yet we are seeing them starting to be operated but in general all of the rules pertaining to workboats are written around the fact that there will be a crew on board.

Moving towards unmanned vessels could open up a big can of worms in terms not only of regulations but other factors such as insurance and responsibility.

The second factor is attitudes and trying to change a tried and tested system can be a long slow process.

We have already seen this in a number of areas of workboat operations such as the move from slow to fast pilot boats and from slow to fast lifeboats.

The sea is not a very tolerant place to operate many vessels and it is easy to stay with the tried and tested solution because you know it works despite what might be seen as shortcomings. However there is a new spirit of innovation coming in, mainly being led by new areas of operation, firstly by the offshore oil and gas sectors and more recently by the wind farm sector. Operators are becoming much more open minded and that could be the catalyst that spurs the development and implementation of unmanned vessels.

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8 A proposed autonomous fire fighting vessel. Left: An autonomous RIB with the capability of launching and recovering a drone

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SAFETY & SECURITY

CHAPTER SIXTEEN

SAFETY AND SECURITY

8 Good viability from the helm is vital to safety

of survival AFTER things have gone wrong. When they are called safety equipment the inference is that if you carry this equipment you will be safe when you go to sea but nothing is further from the truth and you will only be safe if you plan and prepare everything BEFORE you head out to sea. This so-called safety equipment should be called survival equipment because that is what it offers, a chance of survival when things have gone wrong.

Your liferaft may give you a chance to abandon ship if your boat is sinking and then you can hope to survive in the liferaft until help comes for your rescue. It can be much the same with life vests, which can give you a chance to stay afloat if you should be unlucky enough to fall overboard.

The life vest should extend your survival time in the water to give potential rescuers more time to pick you up. Carrying flares and having a radio on board will give you the chance to call for help after things have gone wrong and carrying fire extinguishers will give you a chance to fight a fire on board after it has started.

Note that none of these so-called items of safety equipment will do anything to prevent the crisis starting or occurring in the first place so they are very definitely survival equipment, equipment designed to give you another chance. So how can you arrange to make sure that your boat is safe when you head off to sea so that you don’t have to rely on this survival equipment?

Safety at sea relies on a wide variety of factors. Your chances of being safe at sea can be improved considerably if you plan things before you head out of the harbour. Firstly is the boat in good order so that something does not fail under the increased stress when a boat moves about in waves.

Many boats get into trouble at sea because something on board has failed so the first aspect of being safe at sea is to reduce the chances of failure. This, of course, means keeping your boat in good order so you need to carry out regular inspections. It is so easy just to open up the engine hatch and have a quick look around but to ensure safety you need a much more detailed look. Are there any signs of corrosion, are the engine cooling water pipes in good shape and not swollen or leaking? Are there any fuel or water leaks? Are the electrical connections in good shape and not showing

The words safety and survival mean different things to different people and they are two different stages in the quest to prevent accidents. My argument is that safety means stopping things going wrong in the first place so that any voyage or operation can proceed on its planned course. Survival means having another chance to survive when things have already gone wrong. If work and patrol boats want to be safe at sea then the best solution is to make sure that things do not go wrong in the first place. That should be the focus of safety at sea and it sounds simple but it can often be hard to achieve because there can be a lot of pressures on skippers when they head out to sea and those sorts of pressures are the ones that can be the catalyst for things going wrong and you can start on the downhill spiral when you need to switch to survival mode.

The difference between safety and survival can be quite critical and it is strange that much of the equipment that boats are obliged to carry on board such as liferafts, flares, fire extinguishers, lifejackets, etc is called safety equipment.

None of these items contributes to your safety at sea, they are all carried so that they may provide you with some hope

Credit: FB Design

8 A casualty recovery system on the side of a lifeboat. Far right: A inflatable bag can provide immediate support for a casualty

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SAFETY & SECURITY

any signs of corrosion? There can be a long list of things to check and it is not just in the engine compartment but in all those hidden areas such a in the bilges and behind the dashboard and in the lazerette. If something is showing signs of deterioration then you can be certain that it will not get better on its own and it should not be ignored.

Then consider the navigation. When carrying out passage planning to decide the route that it is planned to follow, are there adequate safety margins around dangers? Have you built in time and distance from dangers so that if something does go wrong you have time to sort it before you drift into danger? Have you considered passing through areas where there might be extra dangers such as strong currents?

WEATHER FORECASTS Finally it is the weather forecast that needs to be considered.

The weather can play a significant role in most workboat operations so quality forecasts are vital. Weather forecasts come in a variety of shapes and sizes almost to the point that you can find a forecast that will meet your requirements.

You have to pick what you can out of a weather forecast but at the end of the day it is up to you to make the decisions.

Will you be under the shelter of the land? Are the wind and current flowing in the same direction? What sort of conditions can your boat cope with out in the open sea?

These are all factors that you have to consider particularly if you are going to sea on a deteriorating forecast. Nothing seems to be cast in stone as far as a weather forecast is concerned and you will often find a significant vagueness in forecasts such as forecasting winds from force 5 to force 7.

Force 5 might be fine for the proposed operation but force 7 will not so which one for you choose?

Then there are the pressures of work and patrol boat operations. Often the rewards of getting a job done in the workboat sector are dependant on performance and getting the job done. This can mean pushing the weather window in which operations can take place and for instance operations such as getting technicians out onto wind turbines for essential maintenance can involve fine judgments in terms of the conditions. Experience can help here and can be a vital factor in safety. Without this experience, you can have the best safety equipment and routines in the world but it usually requires experience to find the often narrow line between success and failure.

Making these judgment calls it probably the main factor in safety at sea for work and patrol boats but there are many details that need to be considered as well. The rules and regulations that govern most work and patrol boats these days cover how the boats have to be designed and constructed with particular emphasis on stability the ability to cope with adverse conditions such as water drainage from the deck and watertight integrity. These are all aspects that can be quantified and measured so that provided the boat is well maintained you can be reasonably assured that nothing will fail. It is that question of maintenance where many vessels will come unstuck because a vessel that is out of action being maintained is not earning money and yet that maintenance is vital to keeping the boat running and operational.

HEALTH AND SAFETY Then there are what might be termed the health and safety factors to consider and this enters the area of making judgments. Providing crews with suitable clothing and personal safety equipment is important and much of this will relate to both the weather conditions and the work that

8 Connecting tow ropes can be a high risk area of tug operations

is being undertaken. Construction craft are more likely to go for the type of protective clothing that is found on land based construction sites, items like waterproof and hi-vis clothing, boots and hard hats but much of this is not suitable for operations offshore. Hard hats in particular are not suitable wear for fast boats as they are not secured in place and we are seeing a growing use of motorcycle type helmets that fit snugly around the head and are secured in place. Head protection can be important of fast boats as there can always be a risk on banging heads on hard surfaces bearing in mind that boats can make violent movements sideways as well as up and down.

In terms of clothing there are moves towards one piece suits for operations offshore. These are full waterproof and often incorporate boots and hoods and so provide full protection. Work and patrol boats tend to operate year round so protection from the cold is important and when considering clothing the operators have to consider their ‘Duty of Care’ to their employees so they may well go to extremes in terms of what crews are required to wear. When working offshore in the winter survival suits are also a requirement so that there is a chance of survival in cold water and of course lifejackets are an essential part of any safety equipment. Lifejackets are now mandatory wear on most boats and as they say, ‘A lifejacket not being worn is useless’. Today there is a wide variety of lifejackets available that have been developed specifically for workboat operations but it is important that a lifejacket is worn correctly with the straps tight and a crotch strap connected.

SHOCK MITIGATION Now we come to outfitting the boat to ensure the right level of safety and security for the crew. This is an area where there are few rules and regulations and once again it comes under the umbrella of Duty of Care although shock

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SAFETY & SECURITY

Credit: FB Design

them, perhaps several times more than the weight of the human body so they need to be strong and capable of supporting perhaps up to 500 kgs. Placing handholds in the right places is a skill on its own and there should be enough so that there is always one within reach at any time. For pilot boats in particular the Hadrian Safety Rail systems helps to provide security when moving around a deck where it is not practical to have side rails. With this system the person has a harness that can be hooked onto a slider by means of a short safety line with the slider connected to be able to slide along a rail built in around the superstructure. It is a good safety feature that should find application on work and patrol boats where transfers have to be made at sea.

8 Secure seating is vital to fast boat operations

mitigation which can be measured comes into this. It is now common for fast patrol boats to be fitted with sprung seating that is designed to reduce the impact of the boat pounding in waves from the boat to the human body. This is now extending into the area of pilot boat seating where it is important for the pilot to arrive at the ship he is boarding in good condition and the same applies to the ‘passengers’ on CTV’s.

Sprung seating is usually designed just to absorb the impact loadings in the vertical direction which is fine if the boat lands squarely upright in the water. This is rarely the case and there will always be more transverse impacts so if the seating is going to be effective it needs to be shaped to provide lateral support, particularly for the head. The jockey type of sprung seat is fine for smaller craft such as open RIBs because there is little space for anything larger that can offer more comprehensive support. For patrol and pilot boats with enclosed wheelhouses there is scope for a more embracing type of support seat and these should be fitted with full harness seat belts so that the occupant can sit down and strap himself in and then relax to a certain extent without having to hold on all the time. Seating for fast boats is still a work in progress to find the best solution and it has to be remembered that providing secure and safe seating is only part of the problem and the way in which the boat is driven can do a lot to make lie on board more comfortable and reduce the intensiveness of the shock loadings. To help the driver of the boat know when he is approaching the limits of comfort tolerance we are now seeing instruments fitted to fast boats that can give an indication when reasonable limits are being reached and when speed needs to be reduced or other action taken. It can be a narrow line between reducing the impacts that can be comfortably tolerated and making fast progress to get the job done. It used to be the case that it was the boat itself that set the limits because of what the boat and its machinery could tolerate but now as boats become more capable it is the human being that has become the weak point in the equation.

HANDHOLDS In addition to being safely strapped in for security and comfort crews also have to move about the boat on occasions and to facilitate this there is a need for secure handholds to be located around the boat both inside and outside. Boat handholds can have high loadings placed on

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CASUALTY RECOVER Pilot boats have also led the way with casualty recovery systems because of the risk inherent in transferring to and from the boat to the ship. The recovery system usually comes in the form of an elevating platform attached to the transom where the casualty can be floated on and then lifted under power to deck level. This is one of several casualty recovery systems that have been developed to facilitate what can be a very difficult operation. Some of the more simple solutions are designed to put a noose around the casualty so that they can be brought alongside but that still leaves the problem of getting the casualty on board. A variety of line throwing devices are available that can help when the casualty is mobile and able to help in the recovery but in a worse case scenario the casualty is unconscious and any recovery system has to be able to handle this scenario.

For this there are various systems that have been developed in addition to that pilot boat solution. Some of them involve using a davit and purchase to do the lifting once a strop has been placed around the casualty. Others use a sort of stiff netting that is deployed down the side of the vessel and then placed under the casualty so that they can be rolled up in the net to bring them inboard. It is important to try and keep the casualty horizontal during recovery as this is reported to reduce the possibility of further medical problems. Many workboats are now required to have a rescue area marked on the side of the hull in yellow and black stripes and whilst this might give some idea of the best place to recover a casualty it does little to tackle the major problem of getting the casualty on board.

8 Full seat harness can reduce crew fatigue on fast boats

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SAFETY & SECURITY

It is important to try and keep the casualty horizontal during recovery as this is reported to reduce the possibility of further medical problems

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Part of the safety and security regime is that crew members have to have had basic training in first aid so that they can deal with casualties of one sort or another and the carriage of a first aid kit on board is mandatory as well as common sense. Once again the first aid kit is part of the ‘safety equipment’ when in fact it is another piece of equipment to deal with a casualty after an accident has happened and so should be part of the survival equipment.

Safety and security is best tackled by prevention rather than but cure and it requires careful study to look at work or patrol boats and identify the potential risks that might be involved and to find solutions. Much of this should be done at the design stage of the boat but the designers and naval architects rarely have the knowledge and experience to go into the design at that level of depth. It is much easier to identify potential problem and risk areas once the boat is operational but at that stage it is harder to find suitable solutions. Most operators, particularly those involved in the carrying of ‘passengers’ are required to carry out a risk assessment of the operations of the vessel and making sure that solutions are found to minimise any risks so that any high risk areas of the operation can be clearly identified and hopefully, mitigated.

For fire in the accommodation or other areas of the vessel the usual solution is to place fire extinguishers at strategic points. These should always be near the exit of the compartment or even just outside it so that the fire can be tackled without having to actually enter the compartment. Fire is a challenging thing to deal with out at sea and even in a worst case scenario when the crew have to abandon ship and take to the liferaft it can be challenging to launch the liferaft on the lee side where smoke and flames might be present and where if you launch on the weather side away from the fire it may be difficult to actually get away. As with most thing to do with safety and security prevention is better than cure and as far as fire in concerned prevention is largely through careful and thorough maintenance.

8 A casualty recovery system tht keeps the casualty horizontal.

Left: Another casualty recovery system for workboats

8 Drones are a new way of connecting ropes for towing and recovery operations

FIRE The risks of a fire on board have to be considered with the engine compartment probably representing the major risk area as far as fire in concerned. This is why engine compartments are fitted with systems that allow the compartment to be flooded with an inert gas that stops oxygen getting to the fire. A fire cannot burn without oxygen but for this gas suppression to be effective it should be possible to shut off any openings such as the air intakes and of course to stop the engines. If a fire is suspected in the engine compartment the temptation will always be to open it up to check what is burning but that would normally be a big mistake as the fire can flare up but it takes some discipline to keep the compartment closed and just start the fire suppression system.

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FINANCE & INSURANCE

CHAPTER SEVENTEEN

FINANCE AND INSURANCE the operational budget as routine payments and thus be much easier to get approval for. This can be particularly the case where it is official bodies rather than commercial ones that are making the purchase. So financing has to be both creative and flexible to meet the needs of the purchaser as well as the supplier. Let’s look at the various ways in which financing for new build projects can be arranged.

8 Workboats can operate in extreme conditions making it difficult to asses the risks involved

Financing and insuring workboats are specialist areas mainly because of the wide variety of craft that are involved and the variety of duties that they carry out.

When you look into these areas in detail it becomes apparent that each work or patrol boat operates in a very individual manner and the range of duties that they undertake is equally varied. Because of this the financing and insurance of work and patrol boats is equally individual with the details and risks being assessed on a vessel by vessel basis.

NEW BOAT PURCHASE When placing a contract for a new work or patrol boat the conventional or perhaps traditional way to finance it is to pay a percentage on the signing of the contract, and then make stage payments according to an agreed schedule with the final payment before delivery. Today finance is a much more sensitive issue and can be the deciding point about whether a contract is placed or not, with the design of the boat being sometimes a secondary issue. It is easy to assume that financing is the problem of the purchaser and that the boat builder only comes on the scene once the finance is in place. This is a naïve view in the modern world of work and patrol boats and if the boat-builder is in a position to arrange the financing or at least produce alternative methods of financing then they can have a significant edge over their competitors and they are going to be in a much better position to get the contract. In most cases, operators of work and patrol boats are not financiers, and they will generally welcome any help offered to them in this way which in turn can bring the contract to that boat builder even though the price he is offering is not the most competitive. For the purchaser there is also the budget to be considered with an outright purchase usually showing on the capital budget whereas a more creative solution might be found with financing that can show on

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LEASING Leasing arrangements are common in the car, truck, container and various other transport sectors, but are still something of a rarity in the work and patrol boat sectors.

However, the principle is the same, where the leasing company pays the capital costs and then recovers these costs through regular payments over a fixed period. At the end of this fixed period, the vessel either returns to the leasing company or can remain with the operator on payment of a fixed, agreed sum.

The attraction of any leasing agreement is that in the case of a commercial company, it does not extend their borrowing or debt and the regular and fixed payments simply become part of the operating cost. The main attraction is that the costs are fixed and can thus be easily quantified. Another of the attractions of leasing is that it switches the costs from capital expenditure to operating costs which can often be more comfortably accommodated under the budgets as we mentioned above. This can possibly make it easier to get approval for the new craft because the approval channels are less demanding and may not require reference to the same level of high authority.

Most leasing agreements insist that a full service, maintenance and insurance agreement being enacted alongside the main agreement. This means that virtually all the operating costs except fuel and crew charges are covered. Such an agreement reassures the leasing company that the boat is being regularly and adequately maintained and is maintaining its expected second hand value. Such a secondary agreement can be serviced by the boat builder thus adding further value to the contract and creating a regular cash flow.

GRANTS AND LOANS There are grants and loans available for a wide variety of purposes and any boat builder should be familiar with and exploit these cash sources in the search for contracts. These grants and loans can range from product development and staff training through to tourism and environmental grants.

They can be available from both national and EC sources as well as from foreign countries where the customer rather than the builder may have to apply for them.

Grants and loans are well worth researching because they can make a considerable difference to the value of a contract or to obtaining money to help with development.

This research can be a time consuming operation but in most countries, there are consultants who specialise in

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FINANCE & INSURANCE

finding and accessing these grants and loans and this can be a good investment. However, any grant or loan usually comes only after a great deal of paperwork and the time scale required to make the application and to get approval may not fit in with a client’s time scale. The important thing is to know what might be available so that development could be steered in the right direction or clients helped in making applications.

Another source of loans for boat building, particularly in the workboat and para-military sectors comes from engine manufacturers. Both Caterpillar and MTU operate such loan systems and it is likely that other engine manufacturers do as well. These loans are made usually at attractive interest rates with the boat offered as security. The loan tends to be offered to the operator rather than the boat builder, but not exclusively so, and it offers a source of raising money against the value of the boat when other sources of loan may not be available to an operator. Of course, the loan is only made if the engine manufacturer’s engines and/or generators are fitted.

Engine manufacturers and other equipment suppliers may also supply engines or equipment with a delayed payment date, particularly when a new type of craft is being developed. The manufacturers reasoning for offering delayed payment is that if his equipment is seen on a successful prototype then it has a good chance of being specified by future clients so he may be making less profit on the first contract in the hope of attracting future contracts. Delayed payments like this can help with the funding of prototypes and can improve cash flow.

JOINT VENTURES Some boat builders can become involved in joint ventures with clients. In some cases a direct subsidiary is formed to own and operate a boat or boats. This system has been used in order to get new ferry concepts operational and to the outside world it suggests that the new concept has been bought and is operated by a new company, with the connection with the boat building parent not directly apparent. The suggestion is that the client company has evaluated all the alternative concepts and implies that the chosen one is the best.

When a client is setting up a new operation, say a charter company, then the boat builder supplying the boats could accept part of the risk by taking a share in the operating company. This share, which would usually involve the supply of the boats, would be offset against the future profits from the operating company. As the ownership of the boats could remain with the builder there is a degree of security in this type of operation, but it does tie up capital unless the boat’s value can be offset against a loan.

CHARTERING There are now several companies that have been set up to charter out workboats to clients so that a direct purchase is not involved. A client needs a workboat for a specific contract and the simple solution is to charter a suitable craft, perhaps with its crew as well just for that job so that it is handed back at the end of the charter contract. Several of the major vessel builders that serve the workboat sector have entered this charter market because it means that the vessels for charter can be built when other contracts are slow in coming and thus keep the workforce fully employed.

Chartering can also mean that specialised craft can be available for short term requirements without the commitment in the long term. An example of this is found

with RIB charter where a contractor is required to provide a safety boat for over water construction work and the RIB charter company will supply a boat and crew and also have a back-up boat available if the primary boat fails to function correctly. The contractor has a reliable service being provided without have to be involved in its day to day operation whilst the charter company gets useful employment for its boats.

CREATIVE FINANCING It should have become apparent from the foregoing sections that there is a variety of methods for operators to raise the necessary financing for boat purchase. Operators are rarely skilled in the financial aspects of boat purchase and a boat builder who can develop creative ways of raising capital, loans, grants or even leasing systems will often be able to secure a contract where competitors have failed. It is suggested that financing is the key to successful boat building in the modern world and the successful boat salesman will have researched all the various possibilities before contact with potential clients, ensuring that he has a very good idea of what might be on offer before discussions start with the client. In addition to these methods suggested for raising money for boat purchase, it is also possible to approach shipping and marine banks which specialise in loans for marine craft. Even normal banks are always open to good financial propositions, although they may be less willing to take a boat as security.

FOREIGN EXCHANGE CONTRACTS Operating in international markets can be fraught with difficulties as exchange rates fluctuate. With foreign contracts the currency for the contract has to be chosen with care and, to guard against negative changes in exchange rates, it is normal to buy currency forward so that a fixed exchange rate effectively operates on the contract.

These exchange rate fluctuations are just one more financial factor to be considered in the marketing of workboats. It will become apparent that the financial skills required to operate successfully in this sector of the market are considerable and at least equal to, if not exceeding the boat design and building skills and these financing aspects of marketing should receive as much, if not more attention than any other aspect.

VALUE ADDED BOATBUILDING Quite reasonably, most of the attention in the work and patrol boat markets is focused on the design and capability of the boat and its equipment. The operator is interested whether the boat is capable of doing the job he wants it to do and he is probably equally interested in the price because he has a budget allocated or a certain value he cannot exceed. Contract negotiations will tend to revolve around these aspects and these will tend to be the main areas of competition when competing builders are after the same contracts. However a builder should look outside the immediate aspects of the contract and be prepared to offer other services. This will not only demonstrate that he can cover all the requirements of the client, but it will also demonstrate that the builder is deeply involved in the work and patrol boat market.

The brokerage market for second hand, commercial and para-military craft is slowly expanding but is a considerable way from maturity. There are considerable advantages in setting up a brokerage operation to run alongside a new boat sales operation even though at first sight it would

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FINANCE & INSURANCE

Most brokers operating in the second hand market do so on a commission only basis. The brokers do not own the boats they are selling. If boats are taken in part exchange for new boats, then in this case the ownership of the boat will be in the hands of the brokers

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appear to be in direct competition. Firstly it has to be accepted that if second hand sales are not handled by a new boat builder, they will be handled by another company, so they will not go away. The second hand boats will not be scrapped just because there is no broker to handle them.

The advantages of operating a brokerage alongside a new boat sales operation are threefold. Firstly, it enables an old boat to be taken in part exchange for a new one, and this can open the way to new boat contracts which otherwise might not be available. Taking an old boat in part exchange can be an important part of the financial deal which makes the whole project viable, and by taking the old boat off the operator’s hands he has one less thing to worry about and is more likely to proceed with the deal. Secondly, by playing an active role in the second hand market, the boat builder is likely to come into contact with a lot of potential clients. Every second hand boat buyer is also a potential new boat buyer of the future and operating a second hand market can usefully widen the client base.

Thirdly, operating in the second hand market can bring useful work to the boat yard. Most brokers simply turn a second hand boat around and offer it for sale in the condition it was when bought in. The reputation of both the brokerage and the yard can be enhanced if the second hand boat is refitted before it is offered for resale and if it can be offered with some sort of guarantee. There is a distinct lack of good quality second hand commercial and para-military craft on the market and a refit can introduce the element of quality into this market, the reputation of the yard can be enhanced, and as this refit work can often be fitted in around the highs and lows of new-building work, it can help to smooth the work load in the yard.

Most brokers operating in the second hand market do so on a commission only basis. The brokers do not own the boats they are selling. If boats are taken in part exchange for new boats, then in this case the ownership of the boat will be in the hands of the brokers. This is what can justify the refit work because it is raising the value of the boat.

However, it should be borne in mind that the capital required to operate a brokerage in this way is considerable, but then the rewards can be equally great and the additional contacts and connections made in the market place in this way are a valuable hidden asset.

SERVICE AND MAINTENANCE CONTRACTS Service and maintenance contracts are becoming a more familiar part of the work and patrol boat market but they can particularly feature in some government contracts.

These contracts can be a useful extra to offer clients and from the client’s point of view it means that he can budget his operating costs much more closely with no hidden surprises about expensive repair bills. From the boatyard’s point of view these contracts maintain regular contact with

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the client and provide a useful data base of the boat’s operation and maintenance history. Service and maintenance contracts can also generate useful extra work for the yard and give yard employees an insight into the way the boat operates after it has left the yard which can lead to a better understanding of the need for careful assembly. The direct feed back from a service and maintenance agreement can also prevent any problems with the boat festering into bad relations which might develop between client and builder.

Service and maintenance agreements have to be carefully costed to ensure profitability. Yard staff can be used for the work if the boat is based nearby, but the costs and problems can mount if the boat is for a foreign client. In such a case, the work would have to be entrusted to a local agent and finding a reliable one may not be easy and supervision will be necessary. Service and maintenance contracts should only be entered into if the yard can be sure of maintaining high standards. These contracts do provide the incentive to make sure that the boat is built to a high standard in the first place in order to reduce the costs involved in the service and maintenance contract. Service and maintenance contracts also provide a useful source of cash flow at the yard, but the prime reasons for offering them is that they demonstrate faith in the product being sold and they maintain relationships with the client.

TRAINING Training programmes for crews and maintenance personnel is another extra which can be offered to clients. Training is likely to be required when a new type of boat is being introduced, usually one with a higher speed than those previously operated by the client. It is usually para-military operators who require training programmes because they may not to have their own training establishments.

Operating small high speed interception and chase craft is a relatively new area for most operators and a training course can be an important part of the total boat package when selling into this market and it should be offered with all boats sold. It is possible to sub-contract training programmes to specialist companies.

Finding the right personnel for training work is important and it is normal to use freelance staff, but they should have some factory training themselves before embarking on the training so that they know the boats and their capabilities intimately. Any person carrying out training for the yard is acting as an ambassador for the yard and he should feel comfortable about the performance and capabilities of the boat. This will enable him to demonstrate the right degree of enthusiasm to his trainees, and ultimately to the client.

Because the training is likely to be with para-military trainees, an instructor should have some experience and familiarity with the way such organisations operate.

Training courses can increase the value of a contract, they can add to the cash flow, and they provide a useful way of maintaining contact with, and gaining experience in how a client operates his boats.

PACKAGE DEALS Many boats destined for the work and patrol boat markets do not operate in isolation. They may be required to operate from mother ships or be easily transportable or require special terminal equipment. These requirements offer the possibility to develop special packages which can add to the value of the contract and which can benefit the client by offering a one-stop responsibility for the package of boat

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FINANCE & INSURANCE

and equipment. It can require a careful study of the market to develop these packages if they are to be marketed without specific requirements developed by clients. The builder should also be willing to take on the responsibility for any complete packages which may be demanded by a client.

One area where a package of boat and equipment could benefit the operator is where a boat operates from a mother ship. It can greatly simplify the job of installation if the launch and recovery system is marketed as part of a package with the boat. Such a package makes the job of the naval architect much easier because he will know that the launch system and the boat will integrate, so he is much more likely to specify the package than have to assemble the components himself. For the operator such a package means that the boat builder cannot blame the launch system manufacturer or vice-versa when things do not work and the package solution offers a guarantee of compatibility. For the boat builder, the package solution adds value and profit to the contract and increases his chance of winning the order.

Commercial and military craft often have a requirement to be transported by road or ship. Road trailers should be part of the package which can be offered by the builders.

For para-military requirements there could be scope for developing a design which can be transported within a 40 foot container so that it can arrive in ‘ready-to-go’ condition at its destination. Air transport capability is another feature which could be offered but that would be mainly for military applications.

To develop these aspects of a business the builder should be able to look at the overall requirements of the potential operator. Just building boats and supplying them to the client is not likely to produce the most satisfactory results.

The client may have expertise in operating boats, but the builder’s skill lies in not only matching the boat design to the client’s requirements but in making sure that it will integrate with the client’s systems so that he has a working package. This requires a willingness to take on responsibility beyond just supplying the boat, and the ability to develop a fully integrated package. In the same way that the builder may have to develop the financial packages to obtain a contract, he must also be prepared to find technical solutions.

INSURANCE Along with financial packages to fund work and patrol boat construction there is the question of insurance. Talking to insurance brokers who operate in this sector the consensus was that for insurance, each vessel and project has to be considered individually and there is little in the way of set fees for insurance. Whilst the hull and machinery insurance may be quite straightforward so much will depend on the type of operations that the vessel is engaged on. A patrol boat that has to go alongside other non-cooperative vessels in the open sea possibly in adverse conditions is obviously at higher risk of damage than say a pilot boat that is engaged in more routine operations. However it is the sheer variety of work and patrol boat operations that provides the biggest challenge for insurers and the potential for extensive third party claims.

One of the challenges for insurers is to evaluate the potential for these third party claims. Take, for instance a fast rescue boat carried on board a stand-by ship at an offshore oil installation. If the rescue boat is damaged and becomes non-operational then there is the potential for the stand-by ship to be off-hire and that in turn might mean that the oil installation may have to shut down leading to considerable on-going costs. Of course the simple solution here is for the stand-by vessel to carry two rescue boats so that it is still operational in the event of the failure of one but such a case highlights the potential for escalating insurance claims.

Passenger carrying adds another dimension to insurance with the potential to add considerably to claims in the event of a disaster. In all work and patrol boat cases the insurance company may limit its liability in terms of what is covered but it tends to be personal injury claims that can lead to a considerable escalation in any claim and for passenger carrying vessels such as the thrill ride type insurance claims can be considerable and the insurance premiums equally high. This perhaps explains why insurance brokers and insurance companies tend to look at each individual case when it comes to insuring work and patrol boats and it can be challenging to assess the risks and reach an appropriate price for premiums. So much is based on past experience when it comes to insurance but with the designs of vessels and the type of operations in which they are engaged, this is a fast changing insurance environment.

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RULES & REGULATIONS

CHAPTER EIGHTEEN

RULES AND REGULATIONS

8 Even small workboats have to be built to stringent safety standards these days

Both workboats and patrol boats operations have come under increasing scrutiny in recent years partly because the authorities do not like this type of operation to be unregulated, partly because the authorities feel under pressure to intervene when there have been accidents and thirdly because this sector has seen a considerable increase in operations in recent years where the boats and the operations have been pushing the limits of what was considered possible. Work and patrol boats now represent a considerable sector with in the marine world and the need for some form of comprehensive regulation became apparent.

VESSEL STANDARDS The British authorities have led the way in this type of regulation where the regulations have been largely developed in cooperation with the industry bodies themselves. This type of mutual cooperation has been pioneered in Britain and has resulted in what is largely seen as a practical set of rules and regulations that can be seen to work within the context of the type of operations that workboats in particular are being developed to carry out. It has been the advent of the offshore oil and gas sectors and latterly the wind farm sector that have placed considerable demands on the work boats that operate in these sectors and they have been pushing the limits both of vessel design and the type of operations that are carried out. By cooperating with the industry the authorities have come up with a set of codes that embody best practice with safe and sensible rules and regulations. The aim of course is to make these operations safer and to try and eliminate the ‘cowboy’ element from the operations which in the long term will bring benefits to all. The aim is to make operations as safe as possible but at the same time allow for innovative and practical operations to take place within a framework of enforceable rules.

Prior to 1998 most work and patrol boat operations came under the same requirements as for shipping such as load

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line and MARPOL requirements but as these largely ignored the requirements of and the particular type of operations that workboats undertake they were not particularly relevant. In 1998 the first Workboat Code was introduced but more recently this has been upgraded and updated to Workboat Code 2 (WBC2) which has been developed by stakeholders in the industry as well as the authorities, in this case mainly the MCA. As far as is known WBC2 is the only set of rules applicable to working vessels less than 24 metres in length with leisure craft coming under the Recreational Craft Directive which is an EU standard.

WBC2 covers vessels that are less than 24 metres in length, carry no more than 12 passengers, may carry cargo and are in commercial use for purposes other than sport and leisure and it includes dedicated pilot boats. The Code applies to all UK workboats wherever they may be operating and to non-UK vessels that are operating in UK waters or from a UK port. It is this latter requirement that has brought many of the foreign, mainly European workboats to conform with these UK standards so that they can operate wherever there is work available. As far as is known there are no comparable European standards so that these UK rules tend to set the standard for the whole industry. The Code covers the manning of the vessels and their operations as well as construction and safety standards.

A second Workboat Code that will embrace the requirements of larger workboats is under development at the time of writing and this will meet the requirements of the new generation of larger workboats and passenger vessels that have been developed to service mainly the offshore wind industry but also the offshore oil industry and other areas of work and patrol boat operations. In particular it will embrace those vessels carrying more that 12 passengers which at present come under passenger ship regulations HIGH SPEED CODE Prior to the development of the Workboat Code, faster craft had to meet the requirements of the High Speed Code. This was an IMO development to provide a set of rules mainly covering dynamically supported fast craft which it was considered were not adequately covered by the normal shipping standards. The HSC originally applied to passenger vessels engaged on international voyages but has since been applied to most high speed craft and it has become the accepted standard for vessels over 24 metres in length and with speeds in excess of 20 knots. This applies to a wide range of workboats these days, particularly those operating in the wind farm transfer sector where the number of technicians transported has risen above the 12 passenger limit where exemptions are permitted with larger longer range craft now carrying 20 or more ‘passengers’.

Regulation is a complex area with so many different authorities involved such as IMO, the EU directives, in Britain the MCA which has been a leader in setting standards and even local harbour authorities. Technical

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developments particularly with high speed craft has meant that the rules are always trying to catch up with reality and one of the reasons that the Workboat Code has been successful is that it has been developed mutually between the authorities and industry with a pragmatic approach.

Certification under the various codes tends to be focussed on stability and watertight integrity as well as the survival equipment that has to be carried and is categorised by the areas of operation which generally relate to the distance from a safe haven. This logic is sound in that the distance offshore will tend to dictate the time required to reach shelter if the weather and sea conditions deteriorate.

CREW QUALIFICATIONS Along with these rules for the design and construction of workboats there is now a requirement for qualifications for the crews. There is a variety of qualifications available, some based on those originally developed by the Royal Yachting Association (RYA) primarily for yachtsmen but now available with a commercial endorsement and some developed by the MCA. These apply in Britain and set the standards but most other countries will have similar qualifications to the RYA ones which are recognised in many other countries. There are two main MCA qualifications, Boat Master and Master 200 tons that will apply to the vessels covered in this book but the Master certificates can be extended to also cover larger vessels such as master 1000 tons and Master 3000 tons. The RYA qualifications that might apply as a minimum for workboats is the Yachtmaster Offshore and the Yachtmaster Ocean with the commercial endorsement usually requiring attendance at additional courses such as first aid and radar. There are also crew qualifications available which also tend be based on the RYA standards.

Added to these workboat specific regulations there are of course the Colregs that dictate the courses of action for all craft in terms of avoiding collisions at sea and they also cover such items as navigation lights and sound signals.

These are part of the wide net of regulation from IMO that mainly involves shipping but which can have a spill-over into the workboat sector.

As a general rule, regulations never get less and are likely to be extended in the light of developments and particularly following a serious accident where the rules and qualifications have perhaps been shown to be inadequate.

For workboat and patrol boat designers the rules can be a challenge to develop advanced designs that may still have to conform to outdated construction rules and they can be a brake of development. For owners and operators conforming to the rules can incur costly surveys and time off charter whilst for the crews there is both the cost and time involved in attending courses and sitting for

qualifications. The problem is that governments have to be seen to be setting standards to ensure safety but at the end of the day it is the personal judgement of the person in charge that will largely determine the safety standards. The requirements for having a qualification does mean that if the skipper makes a serious mistake then the authorities have something they can take away or cancel so crews have something to lose if they do not conform.

8 Simulators can provide an important help in training but are not the complete answer

TRAINING The training to meet the qualification requirements tends to follow the traditional path of partly practical experience combined with classroom teaching. The practical experience tends to entail serving in a lesser role on board for a certain time in order to gain the necessary experience but there is a trend towards doing this practical training at teaching establishments. This can limit the experience gained because these establishments have a major duty of care to the students and so they can only allow operations to continue in mild and moderate conditions. This can be particularly the case where faster craft are concerned and here training may be limited to just RIB operations and classroom teaching which can be poor preparation for real life operations.

Teaching establishments have to tread a delicate path in terms of trying to prepare students for real world operations which is why some are turning to the use of simulators.

Simulators are becoming very sophisticated and now there are units that can provide a classroom experience of driving small fast boats such as rescue RIBs with functioning controls and boat movements. This is a major step forward in training and the use of simulators will expand but they still lack one vital element which is that you can walk away from a simulator unharmed whereas in real live operations you have to suffer the possible painful consequences of mistakes. This is where experience comes in and so far there is no real substitute for this.

8 Realistic training can incur some risk

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THE FUTURE

CHAPTER NINETEEN

THE FUTURE

8 A concept for a future electric ferry for river crossings

Trying to forecast the future of the work and patrol boat sector is challenging because it is a fast changing market but two items stand out as potential major changes for the future. Climate change is the main reason for an increasing focus on electric propulsion and the use of alternative fuels whilst automation is a quickly developing sector with automated boats being developed for a wide variety of work and patrol boat roles. Work is already in progress in both of these areas and in many cases the technology already exists but they are only likely to gain momentum when legislation is developed to embrace the new technologies. Operators are motivated largely by costs and effectiveness and legislation may be the driving force for change as some more traditional way of operating are banned or at least restricted.

Electric propulsion is becoming more widely used but mainly in a hybrid mode where the electric power is only available for short periods or for lower speed operations.

There are two handicaps that are holding back the wider application of electric propulsion. One is the cost and it is estimated that incorporating a hybrid system into a boat is likely to increase the cost of the boat by 10% so there have to be considerable benefits from having this hybrid power to justify this cost. Much of this extra cost comes from the battery systems and this is where we are likely to see development. Currently lithium-ion batteries are used almost exclusively and they are both expensive and have a relatively low power density and there is considerable work going on with other types of battery to raise this figure, most of the research directed towards land vehicle use which is the big market so that the marine side is just a spin-off.

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Zinc-ion batteries are one alternative and then there are lithium-air and aluminium-air batteries, all of which are being researched and developed and a further alternative is the use of capacitors, the type of storage used in grand prix cars to store their electric power. Every system has its potential and its drawbacks and work goes on to find the magic bullet of economical and safe electrical power storage that will open up the market dramatically to the point where electric boats with no diesel power will become the propulsion of choice for a wide range of work and patrol boats. We are likely to see the expansion of electric propulsion firstly in harbour craft but with the advent of fuel cells it can also expand offshore.

Electric motors themselves are also changing and the new motors with printed circuit stators show considerable promise is both reducing size and weight as well as increasing efficiency. Together with battery developments

8 Simulators will be used more and more during training

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THE FUTURE

these could change the face of electric propulsion perhaps allied to the use of fuel cells to produce the electricity.

Similar levels or research are going into alternative fuels and here we have hydrogen, LNG, methanol and ammonia as potential fuels to replace hydrocarbon rich diesel. These fuels can all be made to work in conventional reciprocating engines such as the basic diesel and this could help to smooth the path to more extensive take up to reduce emission levels. However one of the big hurdles to overcome is the storage of these fuels on board. Diesel fuel is stored in a non-pressurised tank which is simple whilst the gaseous fuels mainly require pressure tanks which complicate the issue as well as taking up more space and adding weight.

With hydrogen, ammonia and methanol there is the possibility of bypassing the conventional engine and using these fuels in fuel cells to generate electricity directly, which long term may be the way ahead. A change in the fuels used by work and patrol boats will have to be matched by a radical change in the fuel supply infrastructure and this could have a significant bearing on the uptake of this new technology. It is something of a chicken and egg situation with the lack of easy access fuel holding back its wider use whilst only wider use will lead to the establishment of plentiful fuel points and supplies.

An impetus for the change to ‘greener’ fuels and electric propulsion may come from the increasing reduction in allowable emissions from diesel engines. Currently to make engines conform to IMO Tier 3 requires complex additional engine features which takes up space and adds to costs and complication. We may reach the point where the ‘green’ requirements for diesels will make fuel cell and electric propulsion viable with costs likely to lead the way in the acceptance of change. It does appear though that whichever route is chosen to meet tighter emission standards it will add considerable cost to both work and patrol boats.

As far as automation of work and patrol boat operations is concerned it is also likely that cost will be the main factor in this development. Currently the military are the main users of automated boats because by taking the human out of the equation some boat operations can become more viable. Boats may be expendable in military operations but humans are not and so by taking the human out of the equation autonomous military craft could be seen more and more and they are already being used for mine clearance and some patrol and interception duties. Cost is not usually a factor in military operations but it is for commercial operations and having a crew on board can significantly increase costs both in terms of the personnel involved but also because of the requirement of providing the necessary facilities for them. In some operations such as fire-fighting and search and rescue an unmanned craft could be more effective because like the military, operations could be compromised or restricted when the safety of the crew has to be considered.

The technology for automation is well developed but its adoption is being held back by both safety concerns and by legislation. Most of the rules and regulations concerning work and patrol boats are written to be implemented by the crew on board. Take the crew away and not only do the rules change but new layers of responsibility have to be developed. So the wider adoption of automation is likely to

be a slow process, firstly by having the unmanned craft operating in close proximity to a mother ship and later by expanding the role with control from the shore. Artificial intelligence may even allow autonomous vessels to operate fully independently but that will be a long way into the future and will probably be developed from experience gained from autonomous road vehicles.

As far as the technology for future design development is concerned we are seeing some interesting developments mainly designed to improve performance in waves. Vessel motion control systems are becoming more advanced but can only limit motions in mainly moderate rather than extreme conditions. Getting boats to ride on foils is another modern development so that the hull is lifted clear of the water and in doing so reduces the influence of waves on the hull. Foil design and technology has improved dramatically but as always with the sea there are limits in how much a boat can be isolated from wave influences.

Operators would love to see work and patrol boats that were capable of operating independently of what the weather conditions might be like but that is a hope too far.

The severity of the wind and waves will not change and if anything they are forecast to get worse with global warming so these will always be limiting factors that will be ignored at an operator’s peril.

The past 30 years have seen quite dramatic increases in the capability of work and patrol boats, particularly in the field of high speed craft. This has been mainly driven by vastly improved engines and vessel construction materials but now we are seeing a move towards greater efficiency.

This efficiency is being driven both by the demand to reduce emissions and by the need to reduce costs and at the end of the day it will be largely this demand to reduce costs that will see work and patrol boats being increasingly automated and in developing vessels that can undertake a variety of roles rather than be dedicated to just one purpose. Rather than say, dedicated rescue craft that are just intent on saving life at sea we are likely to see a new generation of emergency craft that can save lives, put out fires, cope with oil pollution etc as well as undertaking routine tasks in order to keep them fully employed.

Economics will pay a large part in future developments with climate change being a major secondary factor and the two could go hand in hand.

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8 Workboats will be operating in more extreme and remote areas in the future

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