CHARACTERISTICS OF DYNAMIC CONTROL OF MID WATER TRAWL SYSTEM IN-FIELDEXPERIMENTS

In order to investigate the characteristics of dynamic control of a mi dwater trawl, a field experiment was conducted by FRV ''SINYO-Maru'' o f Tokyo University of Fisheries. The parameters of the midwater trawl being towed were measured with a SCANMAR system and a self-recording u nderwater load-depth meter. It was shown that the net and otterboards moved deeper or shallower when the towing speed was changed abruptly. However, when the warp length was changed, the handrope tension increa sed or decreased greatly immediately before returning to its original condition, called an ''over-shoot'' phenomenon and this was simultaneo usly observed for the otterboard.