All trawls have an optimal water flow. This varies with construction, mesh size, thickness of net material, knots, whether the material is new or old etc. It is therefore important to tow at a speed that makes the trawl move through the ocean at the speed it was constructed for.
If the trawl moves too fast through the water a type of “bucket effect” is created in the trawl, so that a pressure is formed in front of the trawl. If towing too slowly fish, especially larger fish because of their swimming strength and endurance, are given a chance to escape.
Underwater currents, whether they are with the towing direction, against or from the side, will lead to the water flow into the trawl deviating form what is optimal, unless the GPS-speed is changed and the trawl are pulled skewed in the towing direction to have the water current at 90 degrees into the trawl opening.
The Trawl Speed/Symmetry sensor gives you an opportunity to continuously adapt to changes in the water current so you always have the “correct” towing speed and symmetry.
