High-efficiency semi-pelagic doors give exceptional lift

High-efficiency semi-pelagic doors give exceptional lift

A new design of semi-pelagic trawl doors from Vónin performed well enough for the owners of the trawler used for sea trials to order a pair, based in the way the new Simoon doors handled during testing and evaluation with a variety of single-, twin-rig and midwater gears.

The first trials took place on board Atlantic Viking, before alterations were made to the Simoon doors and four weeks of extensive further testing was carried out on board Nordic Wildfish trawler Molnes, where both skippers were enthusiastic about the performance of these 7.5 square metre, 3000kg doors.

‘Working with 630# trawls, we tried them out at depths from 100 to 350 metres, and under varying seabed conditions and currents – mainly with a double trawl rig, but also using a single trawl,’ reported skipper Remi Teistklub, commenting that the doors square well and are noticeably lighter to tow than regular bottom trawl doors.

“The indications are 20% more squaring power and 5-10% easier to to tow. They’re good in a turn and shoot away easily. Like all other off-bottom trawl doors that are towed with demersal gear, these can lie on their back when in a bad fastener, but hauling in 30-40 metres of warp quickly brings them back upright.”
– Remi Teistklub, Skipper Molnes

The Simoon doors are a high-aspect design that is very much part of the Vónin family of trawl doors, using the same flow booster technology that has made the pelagic Twister and Tornado doors so effective. With a 3:1 ratio, the doors have shown an exceptionally high coefficient of lift, combined with a high-efficiency CL/CD.

Ideal for demersal trawling at speeds over 3 knots, the doors got full marks from Remi Teistklub during the test period on Molnes, and Nordic Wildfish has already ordered a production set for the trawler.

‘The doors are fitted with shoes, which showed very little wear – saving both time and costs,’ he said. ‘We also got a good amount of fish when it appeared on the sonar. So all in all, we have a very positive impression of the Simoon trawl doors so far.’

Co-skipper Jarl Kristian Synnes was also impressed with the Simoon doors, and he also had the opportunity to use them with midwater gear as well as with the usual demersal trawls.

‘The doors were stable during towing,’ he reported, commenting that he was surprised at just how easy they were to tow and at how effectively they spread.

“Especially with the double trawl, in shallow water. In comparison achieving a similar spread, with these doors we have been able to reduce fuel consumption without any effects on fishing”
– Jarl Kristian Synnes, Skipper Molnes

Jarl Kristian Synnes pointed out that the deck crew were also impressed and looking forward to a regular pair of Simoon doors arriving, as the level of maintenance required is less than they are used to, and the new set of Simoon doors on its way to Molnes comes with regular shoes and wearplates to reduce this even further.

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Vónin