Thyborøn take trawl door technology to a new level

THYBORØN TAKE DOOR TECHNOLOGY TO A NEW LEVEL

The Bluestream Type 22 trawl doors introduced by Thyborøn Trawldoor four years ago have been highly successful, but now the company has pushed development even further, while also preparing for full door control of the doors in the water

The new Type 32 Bluestream doors now in use not only show a signifi cant increase in effi ciency, but these are also prepared for remote control functionality – a process that Thyborøn has had in development for some time, but which has been held up by the Covid pandemic.

“Our technical partners in Norway haven’t been able to travel during the pandemic, and that has really held us back on this,” said Thyborøn Trawldoor’s Henrik Andreassen, adding that the parallel developments they have been working on to produce the high-efficiency Type 32 doors and the control options promise a winning combination.

“The Type 22 doors have been extremely successful and we have shown that these are trawl doors with the best CL/ CD on the market today, with satisfied customers around the world. Over the last couple of years we have put a lot of resources into research and development – both towards control while towing and to achieve even more effective designs.”

The Type 32 doors have been tested initially on board trawlers in Greenland and Iceland, followed by a 10m2 pair being supplied for further testing on board pelagic vessel Frank Bonefaas, replacing a 12m2 pair of Type 22 doors.

The first production doors have also reached customers, with Faroese pelagic vessel Jupiter heading for mackerel grounds in international water with its 12.50m2 Type 32 doors which were delivered in Kollafjørður, and Shetland pelagic vessel Antares called in Skagen for a 12.50m2 pair of doors.

Skipper Graeme Sandison said that the new doors replace the 15m2 pair of Type 20 doors Antares has been using for the last five years.

“These should give us the same spreading force as an 18m2 pair of Type 20s,” he said as Antares sailed from Skagen after a call at Karstensens for a paint job and some work on the tanks.

“We were looking for some more spreading power for the blue whiting. But first we’ll get them tried on herring,” he said.

“They look good and hang well at the stern. It’ll be interesting to see how we get on with them. But the Faroese skippers think these are good doors. We’re very impressed with the hydraulic foils. These make it very quick and simple to adjust the doors.”

Refinements to the hydrodynamics, working with CFD simulation and with wind tunnel and flume tank testing, have built on the success of the Type 22 doors and the Bluestream technology to develop something new, while working within the overall dimensions and door weight largely unchanged.

“The results have been better than we could have expected,” Henrik Andreassen said.

“These Type 32 doors have significantly more spreading force than the Type 22s – and those are the best on the market. The Type 32 doors have a deeper curve to the foils which forces a larger volume of water through the door. That makes them both more powerful and gives them even greater stability. This isn’t a small increase – this is a big step in terms of generating spread,” he said and added that the deeper profile of the doors, combined with the high tensile steel that Thyborøn Trawldoor uses, makes these doors even stronger than previous pelagic trawl doors, traded off against a slight increase in weight.

The Type 32 doors are tailor made for each customer and can be supplied either straight or in a V configuration, plus they can be rigged to either V or parallel bridles, and protective door keels can be added for towing close to the seabed.

Ready for full control

It has been a few years since Thyborøn introduced its Flipper option to trawl doors, providing skippers with the choice of altering the surface area of their doors by having these closed or open, but the technology has moved on rapidly in

8 The fi rst

production pair of Thyborøn’s Type 32 Bluestream doors being lifted into position at the stern of Faroese pelagic vessel Jupiter

They look good and hang well at the stern. It’ll be interesting to see how we get on ‘‘ with them. But the Faroese skippers think these are good doors. We’re very impressed with the hydraulic foils. These make it very quick and simple to adjust the doors

going from passive doors to trawl doors that are fully controllable during a tow, as well as adjusting the door parameters to fit the trawl gear.

“We’re very impressed with the hydraulic system,” said Graeme Sandison on Antares. “These are 12.50m2 doors, but we can adjust them down to 9.50m2 if that’s what we need.”

Despite Covid restrictions hampering co-operation with Thyborøn’s technical partners, progress has still been made and the company’s engineers have been developing a hydraulic system that allows the towing point to be adjusted remotely.

Combined with adjustable foils that are the latest evolution of the original Flipper concept, the aim is to offer complete control of the doors with adjustable flow through both lower and upper sections of each door, so that spread and positioning can be adjusted as required for the depth, target species and other parameters. This allows the same doors to be set for stability when working in deep water, and can also be re-set to be fully effective close to the surface.

According to Henrik Andreassen, the previous manual setup, which is still an option, requires the crew to get access to the doors to change the foil positions and lock them in place before the gear is shot away.

“This isn’t always easy on a moving deck in heavy weather, so we have introduced a hydraulic arrangement. To make an adjustment, the deck crew have to just connect a hydraulic hose, and a couple of pumps with a manual pump places the foils where they should be. It’s a lot safer, and quicker to adjust the doors this way,’ he said. As well as being quicker and safer to make adjustments via a single easily accessible hydraulic connection point, this option also offers a much wider choice of setting, making fine adjustments possible. “This is a step in the process,” he said. “The aim is for this to be operated wirelessly, with the doors in the water. We can already make a range of adjustments to the doors by altering towing points and foils, and once we can do this remotely during a tow, we’ll have fully controllable trawl doors.”

8 A few pumps with a hydraulic pump attached to the door is

enough to adjust the foils of the Type 32 Bluestream doors The aim is for this to be operated wirelessly, with the doors in the water. We can ‘‘ already make a range of adjustments to the doors by altering towing points and foils, and once we can do this remotely during a tow, we’ll have fully controllable trawl doors

8 Shetland pelagic

vessel Antares is starting out on herring with the new Type 32 doors

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LONGLINE HARDWARE GOES ELECTRIC

There has already been plenty of interest in new electric longline systems, even with the new equipment is still in its trial phase on board some of the most successful Norwegian longliners.

The new Mustad Autoline equipment represents a shift to electric longline deck hardware, with the EL-hauler being trialled on board Loran since September last year and a new generation EL-Hookcleaner being rigorously tested on board Seir.

Environmental considerations are partly behind the move to electric technology, reducing carbon footprints and contamination risks, and offering lower sound levels, but a central aspect of this is the volume of data that becomes available through embedded electronics. Major European manufacturers, including Siemens, Bosch and Wittenstein, integrate sensors in the motor and even use the motor itself as a sensor.

“In our new components, we use the same industrial level of data collection that’s in an industrial robot or in an electric car. We are using technology that is top of the range in Europe today,” said Mustad Autoline’s VP Sales & Service Svein Erik Bakke.

“An electric system provides accurate measurements of the hauling process. There is responsive and accurate tension control and you generally get more information, and faster. While we can count maybe twelve pulses per revolution on a hydraulic motor, we will be able to count about 36000 positions per revolution of an electric motor. We get a greatly improved response time and again higher accuracy on the mooring function compared to the hydraulic system, and as the line is hauled in a more or less constant speed, this increases the chance of saving more catch on board.”

According to Loran’s skipper Ståle Dyb, the greatly improved response time that the electric system offers compared to conventional longline hardware is that the hauler adjusts accurately for ship movement, slowing down

8 Mustad Autoline is trialling a new range of electric longline hardware

to almost nothing as the vessel lifts, and accelerating as it drops down the wave. As a result, the catch is better and the fish are bigger, as with a constant pull on the line, fewer fish are lost.

“This new system compensates to a much greater extent for vessel movement,” said

Svein Erik Bakke added that Mustad Autoline’s investment in developing new technology is rooted in the company’s strategy and environmental policy, and its determination to be the leading supplier of technology for one of the most sustainable techniques.

“The new E-line product range is developed in co-operation with our customers. The new machines are produced in our factory in Gjøvik, and tested over a long period of time in actual operation at sea,” he said.

As well as reducing overall energy consumption, there are also options for connecting the system to send data to the cloud, where it can be stored and displayed through an app.

“This allows engineers, owners and Mustad Autoline’s service department to monitor the system’s condition and events,” he said.

“The app displays important data such as error codes, temperatures, tail speed, tail power, bait percentage, and more. We can also set up alerts in the app which means that our service can receive e-mail or push notification as soon as an error code occurs, so they can provide preventive maintenance pointers, and detect faults before they lead to downtime.”