Dynamic Simulation of a Midwater Trawl System's Behavior

Abstract

In this study, a mass-spring model is used to dynamically describe and calculate the shape and movement of a midwater trawl system. This mathematical model theorizes that the factors constituting the system are the material points and the external forces such as hydrodynamic load, gravity, and buoyancy act on these material points. In addition, it surmises that these material points are connected to each other by springs, the springs do not have any mass, and the internal force acts on these springs. The non-linear differential equations are implicitly integrated with time for guaranteeing a stable solution.
The dynamic simulation by the mass-spring model shows the status of the gear such as fishing gear depth, distance of otter boards, shape of the gear, and tension of each line. It depends on the parameters such as towing force, warp length, force of a sinker, buoyancy of a float, type of otter board and netting materials. The validity of the model is verified by comparing simulation motions of a trawl system obtained from computed values to those from an actual experiment.