Experimental study on mooring force of a single-point mooring fish cage with ship-type truss structure

Safe and efficient large-scale deep-sea aquaculture cage is an important facility leading the development of deep-sea aquaculture. In this study, we tested a single point mooring cage with a ship type truss structure with a 1∶40 wave-current tank model scale, and compared and analyzed the mooring forces of the cage under two different single point mooring modes of normal and failure conditions. On this basis, we studied the effect of netting, wave and current on the mooring force of cage. The results show that compared with the normal condition, the mooring force of the cage under the failure condition increased significantly, having a great impact on the safety of the cage. Under the normal condition, the stress of net cage increased with the increase of wave height, from 12.5 cm to 17.5 cm, and the mooring stress of net cage increased more than tripled. Under the combined action of wave and current, the mooring force of the cage was positively correlated with the velocity but negatively correlated with the period. Compared with the cage without netting, the mooring force with netting increased by more than doubled under the pure wave condition, and increased by 30%–60% under the combined action of wave and current. The results provide theoretical basis and data support for the mooring design and offshore installation of ship truss cages in the future.