Numerical evaluation of the motion response of a truss-type aquaculture vessel

The hydrodynamic responses and mooring characteristics of an aquaculture vessel are evaluated using the AQWA software based on potential theory and the Morison equation. The numerical accuracy is validated through comparison with experimental data. A frequency-domain analysis is first conducted to obtain the hydrodynamic coefficients and to investigate the effects of the net and bottom plate on the motion responses. The results indicate that the motion amplitudes are more pronounced under low-frequency wave conditions, and the presence of nets increases heave, pitch, and roll responses. The installation of the bottom plates of the truss structure will reduce pitch response but increase heave response. Furthermore, a time-domain analysis is performed for the vessel with a single-point mooring system using the lumped mass method. The influences of the net, draft depth and environmental water depth on the mooring performance are analysed. The findings reveal that the presence of nets amplifies sway and roll motions and increases the maximum mooring force to approximately 1.35 times that of the case without nets. An increase in draft enhances sway but reduces heave motion response. In addition, increasing water depth from 15 m to 30 m reduces the maximum mooring force by about 22%-34%.