TENSION OF THE MOORING ROPES ON THE NET CAGE MODEL OF RAFT TYPE IN REGULAR WAVES

The raft type of net cages are generally employed for fish culture in coastal waters. In order to estimate the tension of the ropes mooring the net cages, a model of the net cage was in a waving water tank, and the behavior of the model in regular waves and the influence of the fluid force acting on the model by waves were examined. The result showed that the tension of mooring ropes was received from combined external forces, one being from the specific motion of the net cage caused by waves and the other being the fluid forces. The latter was directly affected by the volumes of floats which changed according to the wave motion. Moreover, a method of modifying the tension of mooring ropes, which holds within the given wave periods, was presented by numerizing the following factors, the number of floats, the wave period and height, and the fluid force depending on the underwater volumes of the floats.