Fishing and Gear Technology (2+1) copy 1

Unit 11 - Trawl fishing gear and operation

11.2.Trawl Diagram
11.2.4.Ground gears used during trawling
Floats and sinkers are used all along the head rope and foot rope to give the fishing gear the desired shape, keep the mouth of the gear vertically open and maintain a good ground contact. Floats are buoyant material which gives an upward thrust due to which the head rope is lifted off. Whereas sinkers are provided on foot rope to give a downward thrust. The vertical mouth opening of the trawl net is achieved due to these opposite actions.

When the trawl net is dragged in the sea bottom, specially made ground rig is attached of the foot rope to offer protection from snags. Rubber discs of appropriate diameter, threaded together in a rope used for trawling in a moderately rough ground. Rubber bobbins of cylindrical or spherical shape and appropriate diameter and weight (230-450 mm dia and 4-15 kg in air) and steel bobbins (230-600 mm dia and 13-155 kg) with a spacer and washers packed on to the steel wire ropes are used for trawling in hard rough ground. Rubber rock hopper disc (400-600 mm dia; 7-21 kg) with rubber spacer packed together using iron link chain are connected to foot rope are also used in very rough grounds. Rock hopper gear causes less wear and tear to the ramp and deck of the vessel when compared to bobbins.