Because of the trawl’s circumference is smaller and the mesh is smaller the further back in the trawl you get, a lot of the water has to get out through the side panels. This is when a “Bucket effect” occurs, which makes the mesh stretch. If this happens in an area with large mesh, the fish escape, or the trawl will be “coated”.
When the trawl bag fills, the “bucket effect” will increase and move forwards in the trawl. Therefore we see that it often takes a very long time to fill the front part of the bag; usually it will pay off to haul, and shoot again.
The Tunnel Flow sensor shows the water flow and angle changes caused by bucket effects, while the Trawl Speed sensor shows the water flow and skewed position. Both show how the water flow is affected by the bucket effect and/or that the trawl is stretched out when the fish gets to the back of the belly.