TWISTER

SMART TRAWL DOORS

The new smart trawl doors

In engineering the new Twister smart trawl doors, Vónin started from the same principles as the highly successful Tornado design, and have in addition to that incorporated shutters that allow the lift force from the flow to be altered on the lower and upper part of the trawl door.

The new Twisters have already proven that they surpass previous designs in terms of spreading force, and are prepared for an active control system that will make these the first ever smart doors.

“One fantastic advantage of the Twister trawl doors is the shutter system, which allows the spreading force of the doors to be altered very simple. One man can adjust the trawl doors from the setting for surface fishing to going deep in a matter of minutes with a straightforward adjustment of the shutters.“

Høgni Hansen, skipper of Høgaberg

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, meaning that the Twister will be lighter to tow when lift (CL) is decreased.

Stability

The skippers who put the Twister doors through their paces during the long testing process were particularly impressed with the stability of these doors, allowing them to take turns during a tow that would not be possible with any other doors.

Max CL: 4,39 (Sintef)

AOA can range as much as 25 degrees

Great stability while turning

Flexibility

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.

Strength

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.

SIZES AND WEIGHTS

SIZE	WEIGHT
6,0 m2	2100
7,0 m2	2475
8,0 m2	2850
9,0 m2	3225
10,0 m2	3650
11,0 m2	3975
12,0 m2	4350
13,0 m2	4725

Read more

Shutters

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.

Going for the smart option

Vónin has its own approach to controllable trawl doors with the Smart concept. Twister doors are already prepared for the installation of this Smart system in which the doors poll each other for spread. Combined with depth sensors, the doors have a situational awareness that enables them to respond according to their programming, with setting options for various fisheries.

The skipper can manage door setting from a smartphone or tablet app, and by making the doors capable of responding to changing circumstances autonomously, there is no need for a hull-mounted transducer and no ship-to-gear communication challenges.

Vónin Twister articles

10m2 Twister trawl doors for 2300 mtr Gannet trawl

Katrin Jóhanna has just been in Fuglafjørður where they discharged their Blue Whiting to Havsbrún. They had been on a quick trip where they filled up the hull with only four hauls.

The best trawl doors I’ve ever used

When new Icelandic trawler Börkur was delivered last year, the choice of doors went to a pair of Vónin’s Twisters. We spoke to skipper Hjörvar Hjálmarsson to get his feedback on how these doors have performed. “I am highly satisfied. 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,” he said.

Great trip with Vónin Gannet pelagic trawl

They caught 2700 tonnes in only 6 tows using the 2600 metres Vónin Gannet pelagic trawl together with a set of 12m2 Vónin Twister trawl doors.

Smart approach to trawl door technology

Faroese fishing gear supplier Vónin was a relative latecomer to the trawl door business, but has achieved some startling results in only a few years, having practically from first principles with its Storm and Tornado doors. Now the Twister doors are showing what they can do.

New Börkur with new Twister trawl doors

Sildarvinnslan’s new pelagic trawler arrived in Iceland on thursday and will they be spreading their trawls with a set of Vónin’s new pelagic trawl doors. The Twister trawl doors, which have been used by Høgaberg and Tróndur í Gøtu have already proven to a have very high spreading power and fantastic stability where the vessels have been able to make impressive sharp turns.

Investing in engineering

Vónin has acquired Danish engineering and design company Volu Ventis. Based in Silkeborg, Volu Ventis and its managing director Søren Hjort have a long background in the energy and green tech sectors, specialising in aerodynamics and hydrodynamics. Volu Ventis will be fully integrated into Vónin’s research and development structure.

Testing the new generation trawl doors

In the last year Vónin has worked extensively on a new pelagic trawl door that can be controlled. The work has gathered pace and it was last week that Høgaberg was pilot testing the new Twister trawl doors with great success. This new Twister will be a active control trawl door and this is a solution that we will be offering in the near future, but we are still in testing phase of the final product

Other relevant products

Vónin Tornado

Pelagic trawl door with an extreme lift. Customers have in average reduced their trawl doors by 25% when switching to the Tornado.

Vónin Gannet

A effective and versatile pelagic trawl with a robust construction for both intensive and dispersed fishery.

Vónin Falcon

Pelagic trawl with a compact belly which is easy to manoeuvre for chasing fast moving marks and get the gear in the right spot.

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