2 types of trawl doors
Have three main functions: opening the trawl horizontally; providing the front bottom contact points of the trawl gear and stimulating fish to swim towards the trawl path.
- Traditional trawl doors relied on the ground shear to spread the trawl (rectangular and V-doors).
- Such doors lost much of their spreading force when lifted off the bottom.
- Recent development has been towards more hydrodynamic efficient doors, maximizing spread forces and minimizing resistance. Another recent trend is increasing the size and weight of trawl doors.
Midwater doors are also called pelagic trawl doors. The demands on the doors are:
- energy efficiency,
- Combining high strength steel with a good design allows both demands to be fulfilled.