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Controllable smart doors

The Twister was first launched in 2020 as manual trawl doors and immediately became a success. Since then, Twister doors have consistently demonstrated superior spreading force, stability, and flexibility over previous designs.

With the integration of active control technology, the Twister doors have evolved to become semi-automatic. This functionality allows operators to preset specific depths directly from the bridge, ensuring precise and reliable performance.

The latest advancement is the introduction of fully controllable acoustic smart doors. This innovation offers complete command over the trawl doors by sending acoustic signals from the bridge, enabling seamless and dynamic adjustments in real-time.

Three different configurations:


These trawl doors boast exceptional spreading force, have remarkable stability and high flexibility. Adjusting the doors spreading force manually is simple thanks to the shutter system.


With all the features of level one, these doors also integrate active control, allowing you to preset a specific depth from the bridge and making them semi-automatic.


Including all the same features as in level one and two, this advanced level gives you full control of the trawl doors by sending commands directly from the bridge to the Twister smart doors.

From the moment we received the Twister trawl doors in 2021, we were deeply impressed – both by their spreading power and their stability.

For the Mackerel season in 2023 active control was installed into the trawl doors, which made the doors semi-automatic. I am impressed with how successful this has been; the semi automatic system has been working from day one with only minor adjustments necessary. The doors maintain the depth even with strong currents on the side and while making sharp turns. Now we have some superb trawl doors.

Of course, the fishing efficiency improves when the doors remain stable at the desired depth, and that was the goal. After gaining control, one realizes how much energy and attention trawl doors without control demand from the navigator on watch. Now, with control, one can focus more on other aspects related to fishing.

Emil Petersen Á Lygnnesi, skipper on Tróndur í Gøtu

The shutters system

The flexibility of the Twister doors is due to the versatile
shutters that alter the flow of water passing between two of the sets of foils, with each door fitted with upper and lower shutters. This offers settings for greater or lesser spreading force, while also providing options for the doors to be set to seek up or down in the water column.

A straightforward crank arrangement allows the shutters to be adjusted easily by a single crewman with the doors at the stern. This patent-pending arrangement means that there are no shackles that need to be moved to adjust the doors.

The shutters are a key element of Vónin’s smart doors concept.

Exceptional spreading force
with minimal drag

The Twister doors were put through a tough testing process to ensure that they did everything the calculations had predicted – and they did, generating even better spreading force than the Tornado doors.

These highly effective new doors are designed for low drag, high efficiency, and high spreading force using and improving on the same flow booster principle that has worked so well before. The spreading force of the Twister doors has been shown in extended sea trials to be exceptional and the doors square away fast as soon as they hit the water.

The CL of the Twister doors at 4.39 is believed to be the highest of any trawl doors on the market, and the CL/CD value varies between 3.16 and 3.60, depending on the shutter settings and the angle of attack. The shutter settings have very little effect on the CL/CD values of the doors.

The Twister trawl door being lowered into the ocean for full scale testing
Twister trawl door

Max CL: 4,39 (Sintef)

AOA can range as much as 25 degrees

Great stability while turning

High flexibility
Remarkable stability

The stability of the Twister doors goes with a high flexibility range. These have been used across several pelagic fisheries, from working on highly dispersed fish at depth, to chasing elusive marks of fast-moving mackerel just a few metres beneath the surface.

Twister doors offer a significant variation in spreading force, depending on the attachment point and shutter settings, offering CL values across a range from 2.65 all the way up to 4.39. This flexibility means that Twister doors are suitable for use with a variety of trawl types and sizes.

Significant variation in spreading force (CL) from 2,65 to 4,39

The twister trawl doors on the Icelandic trawler “börkur”
Newbuilding Börkur was the first Icelandic trawler to go for the Twister trawl doors
Twister on the Faroese trawler “Tróndur í Gøtu”
The Twister trawl doors on faroese trawler Tróndur í Gøtu


Vónin’s Twister doors are built to last. The doors are made from high-quality high-yield steel, with fully welded seams on all joints and all welding procedures are certified.

Steel: Strenx 700, Hardox, ST355

6,0 m22100
7,0 m22475
8,0 m22850
9,0 m23225
10,0 m23650
11,0 m23975
12,0 m24350
13,0 m24725

Read more

I am highly satisfied with Twiser. We have been in all types of fishery – capelin, herring, mackerel and blue whiting since we got the Twister trawl doors. Each fishery has its own challenges, but the Twister trawl doors have not disappointed and have performed very well on every occasion.

To get the trawl doors to seek up or down, we just adjust the upper and lower shutters. These are very powerful, strong doors – these are the best trawl doors I’ve ever used.

Hjörvar Hjálmarsson, skipper of Börkur

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