The successful development and international launch of fully steerable Twister trawl doors for the pelagic fishing fleets looks promising for gear maker Vónin—now looking to apply the same technology to demersal fisheries.
Fishing gear major Vónin’s Twister are fast becoming the trawl doors of choice for pelagic fishing vessels in several countries. What began as a research and development project some six years ago, is now a reality on the fishing grounds—trawl doors that can be fully controlled and adjusted from the wheelhouse.
With third-generation Twister doors already purchased by nearly 50 pelagic trawlers as of late 2025, the equipment is attracting attention among skippers. According to Vónin, the fully steerable trawl doors are now in use on pelagic vessels from the Faroe Islands, Iceland, Norway, the United Kingdom and the Netherlands.
“Twister trawl doors have now proven their value at sea,” said Óli á Gravarbø, sales manager for pelagic equipment at Vónin. “The development has reached the stage where they can be considered safe, reliable standard solutions that vessels can place full confidence in.”
“After several years of work, the development effort is bearing fruit,” Mr. á Gravarbø added. “Progress was initially slow, but increased competition required us to accelerate, and over the past three years progress has been rapid. It has been hard work, requiring considerable time and energy.”
Árni Dalsgaard, the skipper of Faroese pelagic vessel ‘Katrin Jóhanna’, heaped praise on the new trawl doors. “In mackerel fishing, just below the surface, the Twister doors maintain a set depth of 15 meters, even when it’s necessary to turn sharply to catch the school of mackerel,” he said.
‘Works optimally’
“Previously, one door could come out of the water while the other went deep, causing the trawl to bunch up. This often meant spending a lot of time and effort to get the trawl set correctly in the water, which of course affected the fishing.”
“In herring and blue whiting fishing, it is often necessary to get the trawl a bit higher in the water to catch the fish schools,” Mr. Dalsgaard said. “Here too, the fully controllable doors make a significant difference. Now I just adjust the new height on the doors, and the trawl quickly follows. I often wonder if the old trawler captains would have understood this. I sit on the bridge at the computer and simply scroll with the mouse to move the doors—and the trawl—up or down. But it works.”
According to the experienced captain, the fully controllable Twisters also perform well when the vessel is fishing in waters with a strong current. “In such waters with strong currents, there can be a difference of about 100 meters in height between the trawl doors,” he said.
“Then the trawl stands incorrectly in the water, almost lying on its side, which of course reduces fishing performance. But the fully controllable Twisters maintain the same height, even in a strong current.”
“When you can control the doors, it’s a giant leap compared to what we’ve been used to,” noted Bjørn Sævik, the skipper of Norwegian pelagic trawler ‘Kings Bay’, with more than 35 years of experience on the bridge. “It works optimally,” he added. “We looked at price, strength, and references from other vessels. In the end, Twister was the right choice.”
Demersal trials
To strengthen the technical side of the equation and secure a firm service infrastructure for Twister, Vónin opted to partner with Fuglafjørður-based mechanical engineering firm Petur Larsen. That means maintenance and upgrades is carried out locally in Fuglafjørður, in close collaboration with Petur Larsen, who take care of everything from assembling the components of the trawl doors to integrating the technical systems on board, to providing full service—from maintenance and repairs to upgrades, including 24/7 technical support.
Most issues, however, can be resolved remotely while vessels are at sea, according to Vónin.
At present, fully steerable Twister doors are used only in pelagic fisheries; the next step, however, is to offer the same solution for the demersal fleet. According to Mr. á Gravarbø, the same technology used on Twister for controlling the doors will be applied to benthic trawl doors.
“The main difference is that in pelagic fishing the doors are steered relative to the surface, whereas in demersal fishing they must be steered relative to the seabed,” Mr. á Gravarbø pointed out. “The depths are different, which means we need other frequencies and transmission power, but this is not a technical challenge. Demersal trawl doors must also be smaller, more flexible, and more robust.”
“The technical control systems for Twister are the same,” he added, “whether they are used in pelagic or demersal fisheries.”
According to Vónin, work to adapt fully steerable trawl doors to demersal fisheries is moving forward and initial trials have been carried out.
