1Graduate school of fisheries science, Hokkaido University, Hakodate, Hokkaido 041-8611, 2Faculty of fisheries science, Hokkaido University, Hakodate, Hokkaido 041-8611, Japan
This paper describes a process of modeling a towed sampling gear system that consists of a towed net and a vessel. Two inputs into this model are blade angle of a controllable pitch propeller (CPP) and warp length. To represent the flexibility of warp, a lumped mass model was derived by using the Lagrange equation of motion. The system model of the FMT (Framed Midwater Trawl) and R/V Ushio Maru of Hokkaido University accurately simulated the motion of the system in operation.