Trawl doors, also widely known as otter boards, are indispensable core components fitted on commercial fishing trawler vessels, playing an irreplaceable role in modern bottom trawling and pelagic trawling operations across global fisheries.
The primary function of trawl doors is to keep the opening of trawl nets fully expanded and stable during underwater towing. When fishing vessels move forward on the sea surface, the flowing seawater generates continuous hydrodynamic pressure on both sides of trawl doors. This pushing force separates the two sides of the trawl net horizontally, maintaining a wide and fixed net mouth opening all the time. Without qualified trawl doors, the trawl net will easily fold inward and shrink under water resistance, which greatly reduces the fishing area and directly leads to a sharp drop in catch volume.
Apart from expanding trawl nets, trawl doors also control the towing depth and navigation posture of the whole trawling system. Fishermen can adjust the installation angle, weight and connection position of trawl doors to make the trawl net work stably at target water layers, whether for shallow sea inshore fishing or deep-sea offshore fishing. They also effectively balance the left-right swing of trawl nets in complex sea conditions, avoiding net twisting, knotting and damage caused by ocean currents and waves.
In practical marine fishing applications, different types of trawl doors are matched with various fishing demands. Heavy-duty solid trawl doors are commonly used for bottom trawling to touch seabed stably and capture benthic fish and shrimp products, while lightweight streamlined trawl doors are more suitable for mid-water trawling to improve towing speed and save vessel fuel consumption.
Trawl doors are not only simple matching fishing accessories, but key functional equipment that determines trawling efficiency, fishing range and operational stability. Choosing suitable and well-made trawl doors can effectively lower fishing operation costs, extend the service life of trawl nets and greatly improve overall fishing harvest benefits for fishing vessels.