Modeling of a midwater trawl system with respect to the vertical movements

A mathematical model of the midwater trawl system is presented to aid in understanding the dynamic behavior. The equations of motions for the trawl system have been obtained using Lagrange's equation with respect to variables of the displacement of the trawler, the length of the warp connecting the trawler and otter board, the angle of the warp to the horizon and the angle of the hand rope to the horizon. The parameters included in the described model have been estimated using the data of the trawl system movements that were obtained from the midwater trawl towing by the training ship Kaya of Pukyong National University. The movements of the trawl system, calculated using the mathematical model, closely corresponded to the motions of the actual trawl system obtained through the field experiments. The model effectively represented the movement of the actual trawl system. While reproducing the movements of the trawl system using a computer simulation, it is possible to predict the movements of the gear in accordance with the changing parameters related to the gear design and to analyze the gear performance.