The Danish company Thyborøn Trawldoor has developed an automatic height-control system for trawl doors that keeps them at a predefined distance above the seabed during fishing operations. Previously, the doors were equipped with an automatic depth sensor allowing them to be controlled at a set depth below the sea surface, but the new system adds direct control of their clearance from the seabed.
Control unit on the vessel’s bridge.
The height-control system is based on sensors that continuously monitor the position of the trawl doors relative to the seabed and transmit the data to a control unit on the vessel’s bridge. The desired clearance is set on the bridge, and the system maintains this height automatically despite changes in water depth, seabed conditions or towing load. This reduces the need for manual adjustment and results in more stable and predictable gear performance.
The objective is to minimise seabed contact. This can reduce disturbance of the bottom and lower towing resistance, which in turn may reduce fuel consumption. At the same time, wear on shoes, wear bars and other door components is expected to decrease.
The system has been developed and tested in real fishing conditions for several years and is now in commercial use in both bottom trawling and pelagic and midwater trawl fisheries. Today the company offers three types of remotely controlled trawl doors where size and performance parameters can be adjusted from the vessel’s bridge: Type 32 and Type 42 for pelagic and midwater fisheries, and Type 28 for bottom trawling.
About fifty vessels engaged in pelagic and midwater fisheries are now equipped with fully remote-controlled and Wi-Fi-operated trawl doors, and one vessel is already operating fully remote-controlled bottom trawl doors fitted with a height sensor.
Hampiðjan is the agent for Thyborøn Trawldoor in Iceland.
