SKINNY HULL
CANOE & KAYAK SAILING MAGAZINE
www.skinnyhull.com
VOL 1 NUMBER 61
What’s Inside? TARAWA, A PROA FOR ONE .............................. 5 REPLICATING A 1908 MORRIS LATEEN SAIL.. 14 VESTAS SAILROCKET....................................... 26 RECREATING A CLASSIC RUSHTON............... 38 American Canoe Association Sail for Sale 44sq foot sleeve lateen sail. Free rig plans. Stows flat for paddling and storage. USD $322 plus shipping Contact: Marilyn Vogel Green Lane, PA 18054 seashell@entermail.net
On the cover: Not intended as an air craft, SailRocket still sometimes takes to flight.
Skinny Hull covers the world of sailing canoes & kayaks, Chesapeake log canoes, proas and all sorts of skinny-hulled sailing boats. We’re published on the shores of the Gulf of Mexico in Dunedin, Florida. Skinny Hull is the Global Voice of Canoe & Kayak Sailing Editor & Publisher Edward C. Maurer Contact: editor@ canoesailingmagazine.com (727) 798-2366 A publication of Edward Maurer Consulting, LLC. Copyright 2012 All rights reserved. Actions, activities, building, modification, travel, techniques, etc. seen within are examples of what others do and participate in and should only be carried out by qualified individuals. The outcome of your activities remain your own responsibility. Properly wear and use all safety equipment. If you’re afraid of the water, stay away from it. 3
TARAWA, A PROA FOR ONE Gary Dierking
Tarawa was designed to test sail rigs, hull shapes and steering systems to be used with shunting canoes. At 16’ (4.8 M) it is small enough to disassemble and transport on a roof rack. Hull construction is strip composite with redwood strips and epoxy/glass skins. Crossarms are recycled aluminum mast extrusions. The outrigger float (ama) has a hollow box core of wood with additional polyurethane foam and fiberglass on the outside. Two rigs have been tested; the classic Oceanic lateen and a variation of the rig used by Euell Gibbons in Hawaii in the 1950’s. The classic rig requires a little more effort in shunting but performs well with a very low center of effort. The Gibbons rig is an attempt to simplify the shunting procedure and does not require the sailor to move to the ends of the canoe. Testing has recently begun with special attention to stability during the shunt. Steering closehauled and beam reaching is accomplished by slight shifts in crew weight. A steering oar is used for broad reaches and running. Lateral resistance is obtained through the vee-ed asymmetrical hull.
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Note that the boom is permanently attached to the masthead. It can also be attached to a gooseneck and track to fine tune the center of effort. The yard is lashed to a sliding fiberglass collar around the aluminum tube boom. The clew of the sail is fixed to the end of the boom and when the yard is hoisted the sail’s draft can be adjusted with the halyard tension. The sail can be flattened to a degree where a very high wind strength can be tolerated.
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This is one possible reefing method. around the spar and attached with sa bundled inside the fairing.Â
A rectangular “sail cover” is wrapped ail cover hardware. The excess area is
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REPLICATING A 1908 MORRIS LATEEN SAIL Todd Bradshaw
Years ago, I bought a copy of the WCHA reprint of the 1908 Morris Canoe Company catalog and I’ve always really liked the look of the lateen sail rig that they showed as an option. The sail is nicely proportioned, simple and nononsense but elegant. It’s hung just high enough that the boom’s nose clears the gunwales, which will improve performance by reducing the wind’s heeling force, and the non-battened, hollowed leech edge should resist flapping and adds a nice visual sweep to the shape. The sail was cotton and divided up into very narrow, vertically oriented panels. This was done for a couple of reasons. For one, some types of fabric back then weren’t made as wide as they can be on modern looms. More importantly, the closely-spaced seams on the old cotton sails helped control the fabric’s stretch. Some were real seams, where two pieces joined. Others are “false seams”. They look like seams, but are actually ridges where the cloth has been folded back on itself and then forward again, forming a small “Z” in cross-section and sewn down. They reinforced a larger section of cloth with little “load bands”, resisting bias stretch and helping the sail hold its proper shape. By covering the sail with a combination of seams and false seams, dividing it into narrow panels between the seams, it simply made a better performing, longer-lasting sail than using full-width panels of cotton. It also looked better. Some famous designer once claimed that any sail with panels wider than a couple of feet looked like a bed sheet. There is some truth to this. The Morris sails and early Old Town sails all had this simple, narrow-paneled, elegant look. The only advantages of cotton sailcloth today are that it is very soft and limp when you have to handle/fold/stow it, and it’s quiet - doesn’t rustle in the wind much. In just about every other possible category (performance, durability, lifespan, resistance to rot/mold/mildew, strength, shape-
holding ability, bias stability, ease of maintenance, etc.) modern Dacron (polyester) sailcloth is far superior. Cotton is suitable for making a decent sail is also extremely difficult to find, where Dacron is readily available, woven and finished for the exact use that sailmakers have in mind. It does tend to be rather hard and stiff, very unlike cotton, but the sailcloth manufacturers have brought out what’s generally called “Egyptian Dacron” to cater to the traditional and antique boat markets. It’s just about as stiff and hard as other Dacron, but it has been dyed a light cream color, similar to raw canoe canvas, and is made to at least have the color and look of cotton sailcloth, even if it doesn’t have that soft cotton feel.
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As the sailmaking season is winding down, I just happened to have an extra roll of lightweight Egyptian Dacron sitting in the pile and figured I’d build a replica of the Morris sail, with the About Tanba same proportions, approximately the same dimensions and narrow panels to maintain Egyptian Cotton Colo that antique look. It will be Dacron, not Experience has taught us that cotton, but the goal is to make a lowsailcloth will vary in shade even th maintenance, durable sail that looks like “color”. Different weights, dye lots it’s supposed to be there on a boat of that different results. period, and one which won’t require much in the way of special handling by its eventual owner. For those who are interested, I’ll photograph and document the building process, which is basically old-school, traditional sailmaking. I do draw on the computer, but the actual design and shaping work of the sail is mostly done by eye with string or tape, a ruler, battens and push pins, lofted out on the floor pretty much the same way it was done in 1908. Here is our objective, simple, classy, looks great on the hull and it should perform quite well. I scanned the catalog photo and transferred it to the old Mac drawing program that I use for measurement and From left to right: drawing sail plans. The Morris catalog European 5 0z. Tanbark - US 5 claimed it to be 47 sq. ft. of sail area. US 3.8 oz. Tanbark - US 5.5 oz The boat it was shown on looked to be Egyptian - US White either a 17’ or 18’ model, as it had three thwarts. Its depth-to-length looked more In the photo above are three T like a 17 footer to me, so I scaled the hull swatches with white for comparis to 17’ and proceeded to measure the sail. is from a European supplier and lo I eventually arrived at a measured size until it is hoisted as a sail at whic a hair under 43 sq. ft. Even though it’s a other Tanbark. The other samples good, straight-looking profile photo, it’s vary somewhat by weight. Even d certainly possible that the photo had some different shades. lens distortion or the printing in the catalog Available from Duckworks at h was slightly distorted to account for the sail com/sails.htm#colors area discrepancy. It’s also possible that the
original measurement method varied a bit from the methods we use today (or was less accurate). In any case, It doesn’t much matter for this build. I want the same profile and proportions between ark and the hull and sail that I see and have always liked in the catalog. Forty-three square feet is usually ored Sailcloth plenty to move a canoe in the 16’-18’ range well. different weights of Since I doubt there are many original Morris spar hough they are the same packages floating around on the used market, s and suppliers yield the spars will most likely need to be built new anyway, and it’s a pretty simple job. They can be built to the same proportions as the new sail, though original spars would probably work just fine if anybody happened to find some. The photo on the following page shows the catalog photo with the boat scaled to 17’ and the sail and spar measurements added. This is about as far as we go with computerized help around here, and at this point the sail is still basically just a flat and shapeless outline. Time to get down on the floor and start doing some traditional design work. The spots where the sail’s three corners will be are located on the floor, marked with push pins and connected with string. On the luff (front edge) and foot (bottom edge) of the sail, we will add some round, making those edges convex curves. When we eventually lace these curved edges to straight spars (the yard is the 5.5 oz. Tanbark upper, angled spar; and the boom is the lower, z. Egyptian - US 3.8 oz. horizontal spar) the spars will force that extra cloth in the curves toward the middle of the sail, helping to create our sail’s draft (belly). It Tanbark and two Egyptian doesn’t take much round to generate the amount son. The darker Tanbark of draft we need on a small canoe sail. An inch ooks almost Chocolate or a bit more of convex-ness is usually plenty for ch point it looks like any good draft. However, we can be sure that in use s are made in the US, but our long and rather skinny yard and boom are different dye lots will have going to bend some, and it usually happens in a curved shape pretty similar to our convex sail http://www.duckworksbbs. edges. As they do bend, they tend to lose the ability they had when straight to force the edge17
round into the sail’s middle for draft creation. To compensate for this and maintain our sail’s draft, even if the spars are bending, we make the sail edges even more convex. I don’t want to completely bury you in sailmaker mumbo-jumbo, but by the time it’s all said and done on a lateen sail in this size range, the edge round added to the sail’s luff and foot is usually
something on the order of 1” for draft and another 1.5”-3” or so for a spar bend allowance, making the total round amount 2.5”-4”. Once the round amounts are decided upon, the luff and foot curves are made on the floor with a batten between the sail corners and “lofted” out with masking tape to represent the sail’s edges. The hollowed leech edge is also added with a batten and tape. In addition to luff round and foot round for creating draft and shape in the sail, we also use “broadseaming”. It helps us position the draft where we want it to be. Typical sail seams or false seams are 1/2” - 5/8” wide. A broadseam is simply a place where we gradually increase the width of the seam as it approaches an edge. These help give the edge a bit of a cupped shape and help locate the deepest draft in the area just before we started increasing the seam width. Different types of sails and different panel layouts require different styles of broadseams. The Morris lateen is a “vertical cut” (panels running up and down, following the leech edge). The photo on the next page shows the lofted out edge rounds, leech hollow and that big star-shaped thing in the middle is a guide that indicates where the broadseaming will be needed. The top of the sail is closest to the viewer in the photo, the front end is on the left, the back edge on the right. Most of the sail will have the standard 1/2”-5/8” seams, but the long, triangular areas between the broadseam guides and the luff and foot edges will be areas where seams get broadened a bit. The small triangles at the corners indicate where extra layers of fabric will eventually be added for corner reinforcement. Trust me, the theory stuff gets a lot deeper and we don’t have time or space for it here, but hopefully at this point there won’t be any lines on the floor that are a complete mystery to the viewer and we can actually start building something. 19
OK...The tedious theoretical part is over and all of the needed design work has been figured/ estimated (the cut and design of any sail is always a bunch of compromises and estimates) and lofted out on the floor. Let the building begin!
Step #1 is to roll out enough fabric to cover the lofting. This cloth comes 54” wide and as you can see in the first photo below, two hunks of cloth could cover this entire sail. Unfortunately, that wouldn’t leave you enough seams to do much broadseam shaping...and then there’s that “looking like a bed sheet” thing. The minimum panel count on a lateen sail in order to get enough shaping seams is 3-4 panels, joined by 2-3 seams and 4-5 panels with 3-4 seams is even better. That’s what they have on most modern lateen sails for small boats like a Sunfish. In our case, we’re building a cosmetic replica of an antique sail with panels only about 8.5” wide, so that’s what we will do. We’ll end up with around 12 panels and lots of seams to choose from for shaping. Fabric is always placed with the weave square to the leech edge of the sail. Since the leech edge is not reinforced by being attached to a spar, we want the yarns parallel to, or 90 degrees to, the edge to give us maximum resistance to cloth bias stretch. Dacron is too stiff to false seam well, so all of our seams will actually be seams, joining narrow strips of fabric. We start with a long steel ruler and a utility knife and carefully cut our two big hunks of cloth into strips. Each 54” Lofted out edge rounds, leech hollow an wide hunk yields six 9” wide strips of Dacron. needed. The top of the sail is closest to th It would be nice to be able to hot-cut all the pieces, but hot knives tend to make rather erratic cuts and often leave an ugly dark brown melted bead along the cut
nd that big star-shaped thing in the middle is a guide that indicates where the broadseaming will be he viewer in the photo. edges. The resin coating on the fabric does a pretty good job of sticking the yarns together and seams are sewn right along the cut edges, so raveling 21
isn’t much of a problem. Owners may eventually get a few stray yarns raveling out and they can be trimmed off as needed. I figure I’d rather trim a few yarns from time to time than have ugly melted edges on all the panels all the time. The second photo shows our two big hunks of Dacron split into 9” wide strips. They’re left a bit longer than our lofted plan on their tops and bottoms at this point. With our seam overlaps joining them, it will yield finished panels very close to our target 8.5” width. We use a thin, but aggressive, 1/2” wide doublesided, Mylar carrier seam tape to baste the panels together prior to sewing. Dacron is tough to pin and too slick to keep aligned without something holding it together, so all seams are tape-basted. The tape also adds considerable
strength to the seams. Over time, the adhesive cures and after a few weeks the seams are usually stronger than the unseamed cloth next to them. Following the broadseaming guidelines on the floor, various sections of many of the seams will be standard width in some spots and broadened in other areas (toward the sail’s edges). There are no hard and fast rules for how much to increase the overlaps or how often to do it (every seam?, every other seam? etc.) It’s done mostly by eye from practice. I built my first lateen sail in 1980, and remember being very nervous and semiconfused about the whole broadseaming concept. Luckily, at this point I’ve made enough of them over the years that I don’t have to think about it much and do it by eye. The third photo shows all the panels basted together and our sail is no longer dead flat. It has some shape, even though it doesn’t look like much yet. Before we start sewing the seams, we lay the cloth back over the lofting, locate the corners, get out the batten and a pencil, and trace the lofting’s luff and foot edges onto the cloth. Then we cut away the excess on these two sides. The hollow on the leech edge will also be traced onto the Dacron, but we won’t cut it to shape just yet. The next photo shows this work underway. As soon as our edges are marked and trimmed, we’re finally ready to start sewing! Dacron will crease if bent sharply or wadded-up, so during the sewing process it is always left on the floor to prevent unsightly creases. The sail will eventually get some creases from being used and they don’t hurt the cloth, but it’s a point of pride to deliver a sail that’s as pristine-looking, and with as few handling marks on it as possible. The worst part of sailmaking 23
is when you finally have to fold it up and stuff it in a little box for shipping. It leaves a series of horizontal creases that are unavoidable unless the customer is crazy enough to be willing to pay a fortune to ship a ten or twelve foot long tube half-way across the country. Folding creases are just something we have to live with, but we do our best to limit any other sort of creasing. In order to do this, we roll the sail like a scroll on either side of the basted seam and have the longest infeed/ outfeed space possible on either end of the sewing machine. I have a narrow path to sew in on my floor, but it has about 25’ of clear length with the sewing machine set into the floor in the middle. If the scroll-rolled bundle is more than about 12’ long, I start running into walls - which isn’t good and causes creases, so I’m limited when it comes to the sizes of sails that I can build these days. The next photo below shows the rolled sail, temporarily held into its rolled state with a couple of strips of strapping tape. You can see the basted seam, ready to be sewn. Each seam will get two individual passes through the machine. Each lays down a line of zig-zag stitching right along one of the edges of the basted panel overlap. Early cotton sails were sewn with a straight stitch, rather than a zig-zag. Dacron has different stretching and tearing characteristics from cotton, and a zig-zag which spaces the needle holes over a wider distance makes a stronger seam (less like a perforated line on a sheet of paper). Even though we’re shooting for a semi-historic replica of the old sail, we don’t want to do anything dumb, so we’ll stick with a zig-zag. With the combination of the seam tape’s bond and two lines of zig-zag, we will end up with very strong seams that will never let go.
Neatly sewing long seams is rather tedious. I sew one line, guiding along one edge of the seam overlap, then flip the scroll over and sew the second line of stitching along the other side of the seam overlap. I use size V-46 polyester thread and a #16 needle for sails this size. (Just for grins, I measured the length of all those panel seams on this sail. They added up to 62.6’ of seams, which means a bit over 125’ of stitching for both passes.) Once the panels are seamed, there is probably another 70’-80’ of edge and corner seaming to do before this sail is done. We’ll end up with about 200’ of zig-zagging, which is a lot for a 43 sq. ft. sail, but I think the look will be worth it. A couple hours later the panel seams are all double stitched (2nd photo) and we’re done for today. For the next episode, we will make and attach the corner reinforcing patches. After that, we’ll hem the leech edge and bind the luff and foot edges. Finally, we will install the grommets and a couple telltales and call it done. Stay tuned, ‘cause it’s actually starting to look like a sail! We’ll finish this sail making project in the next issue of Skinny Hull! See more of Todd Bradshaw’s work: Sails and sailplans: http://webpages.charter.net/tbradshaw/Sails%20 and%20Plans/ and another old boat, restored and relaunched http://www. theshipmusic.com 25
VESTAS SAILROCKET
Seeking to break the 50 knot barrier under sail We come late into the continuing ultra-high speed aquatic saga of the Vestas SailRocket 2 as it enters another year of research, development and continuing challenges to break speed records and the very unsimple barriers of physics. Let’s take a look at the original SailRocket, now known as VSR1, to get some insight into this continuing challenge of trying to set a speed record in what is truly a Skinny Hull sailboat. Ed.
VSR1: CONCEPT In conventional monohulls and multihulls the leverage of the sail force is countered only by a weight/buoyancy leverage. This results in very definite limits to stability in both the roll and pitch directions. Many speed record attempt designs suffer from the two principal side effects of this limitation – limited drive force and unsteady response to gusts.
Vestas SailRocket employs a wholly different concept (first documented by Bernard Smith in the 1960s) in which the sail and keel elements are positioned so that there is virtually no overturning moment and no net vertical lift. When used
correctly this concept results in a boat which no longer has obvious stability limits and in which the only significant response to gusts is a change in speed VSR1: DESIGN 2003 - Design of a contender for the outright world speed sailing record This project was undertaken by four students as a final year project for completion of their four-year BSc in Ship Science at Southampton University. The objective was to review design options and develop design tools as a first phase towards designing a speed record contender to be completed by subsequent student teams at the University (The boat started construction in 2005). Collaboration with the Vestas SailRocket team proved very fruitful for both parties. The student’s choices and design were informed by the extensive practical experience of the Vestas SailRocket team in high performance sailing and speed machine design. At the same time we gained very valuable 27
data and validation for our design. In particular: Wind tunnel force measurements on the 1:5 scale model with and without rig Validation of our VPP. The students generated their own more general program (applicable to other configurations) which, given the same data , gave very similar speed predictions 2004 - Design Study of Hydrofoils for a Speed Sailing Contender This project was undertaken by Guillaume Thiebault as part of his 1 year MSc qualification at the University of Southampton. The objective was to review the performance of hydrofoils applicable to speed sailing record contenders and evaluate the feasibility and performance of a supercavitating hydrofoil design for SailRocket. A great deal of relevant data was brought together and performance characteristics generated for both sub and supercavitating sections using 2D CFD codes. In addition a supercavitating section was proposed for Vestas SailRocket taking account of both hydrodynamic and structural issues. Once again this was a very successful collaboration resulting a very sound basis for future development of it hydrofoil which we know will eventually become the critical component. 2004 - Aerodynamic design of a wing sail for world speed sailing record contender This was an MSc thesis project by Antoine Derely again at the University of Southampton Ship Science Department. The objective was to produce an optimized geometry for a wing sail to suit the existing Vestas SailRocket plan form. This represented a well defined task which was tackled using 3D CFD code and a variety of plan form and section geometries. The performance characteristic for the best configuration was generated so that we have been able to quantify the speed advantage of going to a wing to be of the order of 7 knots in 21 knots wind! The very real and valuable input to SailRocket’s development was clearly a motivating factor and resulted in an excellent co-operation and final report.
VSR1: COMPONENTS The Crossbeam The crossbeam’s primary function is to provide a base for mounting the rig in the required place 7.5m to leeward of the main hull. It is located on vertical pin at the main hull to allow rotation in the horizontal plane so that the fore and aft position of the rig base can be altered by adjustment of the lower (horizontal) stay lengths.
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Rake of the rig can also be adjusted in the same way with the upper stays. It also acts as a support for the rig weight to lean on (or when backwinded). The flying height of the float is stabilized passively by the aerodynamic ‘ground effect’ which acts like weak spring connecting the beam to the water surface. By keeping the main structural part of the beam symmetrical we are able to use it on either tack* by simply reversing the flap angle. The crossbeam is 8.3m long and weighs 35kg. The main foil The hydrofoil’s function is to balance the lateral force generated by the sail while causing as little drag as possible. As the sail force can approach 1 tonne at full speed it needs to be very strong and stiff enough to avoid significant bending under full load. It is normally inclined at about 30 degrees to the vertical (parallel to the sail in front view) but we have the facility to set it more upright if desired. The Mk I design currently under test was built by DesignCraft and has the following details: • Span: 700 mm • Area: .0.137 m2 • Section: SR230-NC2 (subcavitating) • Construction: Infused carbon shell on foam core
Cavitation is the main problem faced in hydrofoil design. This is the phenomenon in which bubbles of water vapour spontaneously form on the foil surface due to the pressure reduction. Subcavitating foil designs such as the Vestas SailRocket foil, attempt to avoid cavitation, although it is generally accepted that cavitation is unavoidable at speeds significantly above 50 knots. The main hull The main hull of Vestas SailRocket is 9m long by 700mm wide and adopts a unique two stage form which blends the requirements for minimum ‘hump’ drag at low speeds with the requirement to ride on two well spaced but small planing areas at high speed. The third function of the hull is to act as a strong beam to react the fore and aft staying loads needed to support the rig. Low wind resistance was also a factor in design. The forward part houses the main hydrofoil while the cockpit is located in the aft section. The hull is built from carbon/epoxy prepreg (supplied by SP Systems) on an 8mm Nomex core and weighs 55kg without fittings. It has a removable nose cone for access to forestay fittings and in case of impact damage. The Float The function of this float is to support the weight of the rig and crossbeam at low speeds and at rest (by buoyancy) and at medium and high speeds by planing lift. The trim can be adjusted to control planing attitude. At top speed the float no longer contacts the water as the aerodynamic lift of the crossbeam takes over. It is vital that the float generates little or no sideways ‘grip’ on the water as this could upset the roll stability and trip the boat. For this reason it is shaped asymmetrically to skid easily to leeward. The float is of carbon/Nomex panel construction and weighs 6 kg. 31
Strut This acts as a compression strut to push the rig up with and to support the rig weight. In normal sailing conditions it acts like a lower tension stay. This is also a filament wound carbon/epoxy tube by CompoTech. It is 3.0m long and weighs 2.0kg. And finally... 1. Fixed skeg - Hard mounted to the boat, only the trailing edge flap is adjustable. The large fixed forward section makes Vestas SailRocket track straight and dampens down any instabilities. The addition of this skeg made the craft ‘sailable’ over 35 knots. Without it a human couldn’t steer this particular boat at high speed! It has a profile which is optimised for high speed work. 2. Adjustable trailing edge skeg flap Locked in position until we are going fast, this flap is used to steer Vestas SailRocket at high speed. It gives much more accurate control via the hand steering in the cockpit than the large and brutal low speed rudder. 3. Skeg flap release trigger - Releases the skeg flap to allow hand steering and is activated by twisting the handle of the tiller grip. 4. Hand steering linkages - Connects the tiller in the cockpit to the skeg flap (it works... But can be improved). 5. B and G rudder angle sensor - Super reliable... and sensitive. Essential information. 6. Large low-speed rudder - Vestas SailRocket is very ‘unbalanced’ at low speed and needs a large rudder to make it steer both onto and off the course for each run. This rudder accounts for a large part of the ‘wetted area’ of the whole boat when it is down. It really should be raised over 30 knots. I was actually still steering with this when we hit 44 knots. As predicted, it was not nice!!! Raising it should give us another 5 knots of boat speed at the top-end. The amount
of spray it makes when down would vindicate this. 7. Rear planing surface - The rear ‘shoe’ of Vestas SailRocket. When at high speed the boat rides on the last couple of inches of this. It has a wooden core and strong carbon laminate to deal with the punishing chop. We broke one before and it nearly took us out. There are some areas of this boat where saving weight is just not a priority! 8. Foot steering control lines and large rudder pull-down line.
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VSR1: COCKPIT Paul’s Vestas SailRocket Cockpit Tour 1. Side impact bar - To protect the pilot from a side impact if the beam or wing comes back from that side. 2. Pi Research data logger - Needs to be external to give GPS antennae a clear view of the sky. Also needs to be within arms’ reach of pilot so he can hit the ‘event’ button at start of run to synchronize with shore and onboard video cameras. 3. Pi Research displays Left side displays the wing angle, right side displays the rudder angle to let me know if I am in the ‘Groove’ at high speed. 4. Hand steering grip - This is on the connecting rod from the foot steering back to the steering system. This way I can steer with either hand or foot depending on what system I need to focus on. I push to turn right and pull back to turn left. I have 20 cm of movement. The range ±4cm from central is for high speed work and only moves the rudder a fraction of a degree. If the Pi Research display on the left shows that I am outside this range at high speed... then I abort the run and we reconfigure the boat. It means we are not in the ‘groove’ and in danger of a high speed wipe-out. I steer with my feet at start up so my hands are free to control the sheets/wing angle.
t e r
p o T
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5. Marlow control lines - These are set up in order of priority for a rapid release to de-power. From left to right you haveThin white: Flap bridle Sheets in main wing flap as last power option. Red: Main flap spring release - This disengages the heavy elastic cord that deploys the main flap and stabilizes the wing at high speed when released. If I don’t pull in this 6:1 purchase at the start... the elastic keeps the flap deployed and I can’t sheet it in for more power. Blue: Mainsheet - This controls the wing angle. For full-on runs I pull this in to 10 degrees and lock it off in the Harken cleat. I then go to the hand steering with my left hand and sheet in the flap with my right hand. I hold both the flap bridle and red spring release during the run ready to deploy the flap. Only when this is done can I dump the mainsheet. Yellow - Forward wing bridle. This allows me to set the wing at a fixed angle to the boat by sheeting it against the mainsheet. it also allows me to pull the wing to a fully feathered position for a rapid slow down. 6. Cockpit drain ring - I disengage this during a run to allow water out of the cockpit at speed. There is a constant barrage of spray coming in, so it helps to let it out again. 35
7. Adjustable tie-rod - This allows us to make minute adjustments to dial the steering system into alignment with the main foil at high speed. Ideally we want the rudder to be in the centre of it’s steering range at maximum speed. 8. The brains box - The real breakthrough for our craft. It gave us high speed control and allowed us to become a record breaker. It gives us super fine control at high speed and very coarse control at low speed. It’s both simple and robust... but a bit tricky to design. We’ll keep this one a bit secret for now. 9. Strain gauge - Tells us the loads on the rudder stock. It tells us how well balanced the boat is at speed. From this we can rebalance Vestas SailRocket by moving the beam fore and aft or raking the wing. 10. The rear planing surface - This is the skid plate I ride on at the back. It extends over the top of the rudder to reduce the chance of ventilation where air gets sucked down from the surface. 11. The rudder Designed by team member Richard Pemberton and built on-site by the team. It’s a high speed section with an area that allows for low speed manoeuvres to get us onto the course and high A view from the top...note the pilot’s position. That’s his helmet speed manoeuvres even
when fully stalled. It is much bigger than necessary at high speed if the flow is attached and therefore needs very precise steering i.e. 1/10th of a degree is substantial! 12. The tow/ anchor loop This is where we attach the anchor at the very start. when I slip this line from the cockpit...we are off! Discover the Vestas SailRocket 2 in the next issue of Skinny Hull!
- the pointy object at the lower left of the hull...yikes! 37
RECREATING A CLASSIC RUSHTON A princess of sailing canoes John Floutier, Bristol, UK
Over 20 years ago I wanted to build a cruising boat for myself, but I had neither enough time, enough money, nor enough space to do so. I realised that I would never get to build one at all unless I compromised to suit what I actually had. A sailing canoe seemed like an exciting solution to my problem. I has always liked the look of Rushton’s Princess model, the hull, deck and cockpit coaming have such a harmonious shape. I decided to try and recreate one in glued clinker ply. An original Princess called Diana ( 14’ 3” long) is still preserved in the Adirondack Museum. It was built for Lucien Wulsin. The lines and offsets of this canoe were taken off by Orvo E. Markkula in 1967 and appear in the book “Rushton and His Times in American Canoeing”. However, the information is a bit too sketchy to build from directly. I also wanted a longer canoe for use by two people on occasions. Hence I drew out a stretched 15’ 8” version of the hull with the help of some information from Bill Clements who used to build canoes, including a version of the Princess, in Massachusetts. (I think Rushton himself also offered a longer two person version). Although trying to replicate Rushton’s hull shape, I incorporated quite a few ideas of my own when it came to the rig and the details which may be of interest to others. Sailing canoes have always provided their owners with an opportunity for experiment and innovation. Rig: I wanted a sail arrangement which would be traditional and appropriate to the canoe, simple and quick to rig or derig. The masts and spars had to fit within the canoe and be able to be taken down and
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stowed below while afloat to convert the canoe to a paddling canoe and reduce windage if required. I wanted enough area to make good progress under sail, even on light wind days, but with easy reductions in area possible under windier conditions. The canoe might be sailed by either one or two people with or without camping gear. They might like to hang out or sit down within the cockpit. My rig has two standing lugsails 45 sq’ and 20sq’, without any battens. The foresail has a single row of reef points. The mizzen mast + sail and spars can be moved forward lock stock and barrel to a third position just in front of the centreboard case for strong winds. Both yards are curved in the manner of 18th century beach boats (Dixon Kemp chapter XII). The foremast is unstayed, yet set in a slotted tabernacle above deck
level. This keeps the mast short for stowage and allows lowering to go under bridges and easy removal from a seated position in the cockpit. Much of the running rigging is connected using toggles. This is a traditional sailing canoe solution which works well with the light loads on canoe rigging. Mine are 1” diameter varnished discs made from offcut 4mm marine ply, fixed on the end of the rope using a wall knot. Centreboard: How to accommodate a centreboard has obviously always been a problem to sailing canoe designers. A typical sailplan for a canoe, if balanced by a normal pivoting plate of the dinghy type, would end up with the case in a part of the hull needed by the crew. This problem is particularly acute if you may wish to sleep in your canoe as they sometimes did in the past! The Radix folding centreplate was one somewhat complex Victorian engineering solution, keeping the entire plate and case below the bottom boards by collapsing the plate like a ladies fan when in the stowed position. (Reference Todd Bradshaw’s book “Canoe Sailing, the Essence and the Art” for more details). A dagger board raking sharply aft is another possible answer, and this is the one that appears to have been adopted by Rushton in the original Princesses. However, dagger boards are not ideal for shoal draught sailing in my experience, as they often bring the vessel to a rather sudden halt. I decided to design a plate which was a cross between a dagger board and a conventional pivoting centreboard. A similar idea was used on some sailboards. The geometry is so arranged that the board will pivot up below the hull as depth reduces. Most importantly, however, it can then still be totally withdrawn from this position, if required, without any increase in depth. The forward movement of the handle at the top of the plate in the case as you approach the shallows gives much more useful information on depth than any echo sounder when you are interested in the range 2’ to 6”! Tiller: This is another perennial sailing canoe problem. A conventional tiller would foul the mizzen mast, and anyway you would not get much rudder angle generated by moving the end of a tiller of such length across the 41
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narrow width of a canoe. It would also be hard to reach such a tiller when sitting down in the canoe facing forwards. Traditional solutions are: a) A foot steering arrangement with lines to a rudder head yoke. This does not work so well if you plan to hang ( hike) out. b) A sharp crank in the tiller. This worked on the slightly wider canoe yawls, but only because the mizzen mast was very close to the rudderhead and the cockpit well aft. c) A slave tiller on deck in front of the mizzen, connected by lines to a yoke at the rudder head. This is still not easy to reach when sitting centrally and facing forward, and may not feel very positive unless well engineered. The best solution appears to be a Scandinavian style push-pull tiller connected to a single transverse arm at the rudderhead. Despite its unconventional direction of movement, once you get used to it, this works surprisingly well and if given a slight curve to miss the mizzen mast, can even be used when hiking out on the opposite side of the canoe. You need to take some care with the detailing of the joint to the John and Barbara Floutier sailing the princess on the Solent transverse arm at the aft end, and a suitable system of retaining the tiller near the front end. The joint must transmit the push and pull steering force
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with no slack or slop, yet allow rotation in a horizontal plane and also some upward vertical rotation ( eg to allow one to use it when standing up). However the tiller must not be allowed to fall down outside the hull below deck level and get caught in the flow of water and swept aft out of reach, nor be allowed to twist as a result of its own self weight and its curved shape. As a final refinement I have added a brass “stub” on the side deck which engages in a recess on the underside of the tiller near the front end and on which you can “park” the tiller. This allows one to lock the rudder angle, either near straight ahead or, using a second recess, in an offset position for heaving too. Further fine adjustment of the straight ahead setting may be made by rotating a copper sleeve fitted on the tiller in which there is a spiral groove. This moves the position of the tiller slightly fore or aft relatively to the stub attached on deck. By this means one may offset for the effect of a side wind while paddling or enable the canoe to sail a set course by herself for a bit while you attend to something else. My first canoe took me about 650 hours to build. It has given me many years of exciting cruising in the sheltered coastal waters, lakes and rivers in Britain and France, including sleeping aboard on occasion. 45
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John has produced a full package of the drawings seen here to enable others to build his version of the Princess. Alternatively, you could buy a fully finished canoe! Take a look at his website www.floutiercanoes.co.uk for details.
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YOU, TOO CAN BE PART OF SKINNY HULL, HERE’S HOW! WRITERS AND PHOTOGRAPHERS GUIDELINES
This is the preferred way of submitting copy [articles, etc.] and images [photos, etc.]. The easier it is for us to use them, the more likely it is we will! ALL submissions MUST be your original work or submitted with written permission of the creator. Old, historical works are very welcome but you need to inform us about their source. Upon submission you have, for all intents and purposes, certified that what you have sent is your intellectual property or of a historical nature. Copy: -12 point, Times New Roman, left-hand justified ONLY. No fancy formatting, etc. that I’ll just end up undoing anyway. -News pieces: 300 – 500 words -Articles: 500 or more words. Pieces that are more than 3,000 may be serialized—run in consecutive issues. Please tell me you’d like to consider that for your longer article. I’m very open to the prospect for worthwhile topics. -How-to, building and repair/restoration articles: make these photoheavy with explanations for each photo or diagram. -Travelogues: Include plenty of photos, etc. Consider including links to Google Maps. -If you have a particular placement for an image within the document, place its file name in brackets [sailingcanoe.jpg] where you’d like to have it placed. -By lines include your name and your town so we know where you’re from. Images: [ALL images—Includes photos, scans, diagrams, etc.] -100dpi, 1200 px wide minimum. Larger is better! I reserve the right (unless you specify otherwise) to edit images as needed. -Color preferred, but B&W, etc. are a welcome change when appropriate. -Large, crisp images are preferred to small ones. I limit image sizes in the publication, but large ones I can to reduce produce better quality. -Name each file, then provide important info and captions in a separate, clearly labeled document. If the images accompany an article, etc., list the info at the end of the document. For example: sailingcanoe.jpg; photo by Joe Doe; woman in blue is Deborah, man in green is Ed Please email ALL inquiries and submissions to: editor@canoesailingmagazine.com