Field experiment on static characteristics of midwater trawl system

A field experiment was conducted by FRV “Shinyo-maru” belonging to Tokyo University of Fisheries in order to make detailed measurements on operational characteristics of a mid-water trawl system. Time series data describing the net geometry and the towing loads occurring during hauls were measured by SCANMAR system (acoustic spreadmeter and netsonde) and self recording solid state memory load cell and depth meter at the towing speed ranging 2.5 to 4.5kt with changing the warp length from 100m to 500m. It was shown that the spread of wingend increased with increase of towing speed and with increase of warp length. Especially, the change in warp length affects largely the wingend spread.