Comparative Analysis of Hydroelastic Responses of Novel Offshore Submersible Fish Cage in Regular and Real-Data-Derived Irregular Waves

Abstract The Blue Economy Cooperative Research Centre has developed a novel submersible fish pen featuring 2×6 array of high-density polyethylene (HDPE) framed cubic cages (side length of each cubic cage is 20m) for offshore aquaculture. This system is named as the SeaFisher. The cages are stiffened by glass-fibre reinforced polymer (GFRP) diagrid rods. Submersion is achieved through vertical ballast tubes attached to the outer column members of the cubic cages; enabling the SeaFisher to dive to 30m depth during storms to protect both structure and fish from strong surface waves. A single point mooring system is employed to allow the SeaFisher to behave like a weathervane, enhancing its resilience to waves. This study presents a comparative analysis of the hydroelastic responses of the SeaFisher under regular and real-data-derived irregular wave conditions. The hydroelastic analysis will be performed using the software package AquaSim in the time-domain. While irregular waves provide a realistic simulation of offshore environments compared with regular waves, they require significant computational resources for statistically reliable results. This study therefore explores equivalent regular wave conditions as an effective alternative to irregular waves with the view to reduce computational demand by simplifying the analysis. This approach in using regular waves enhances efficiency in evaluating structural limits, supporting the refinement of resilient cage designs for offshore aquaculture systems.