Hydrodynamic performance of the floating fish cage under extreme waves

Abstract Extreme waves with large wave heights may cause the biomass loss and catastrophic damage to the offshore fish cage. This study investigates the hydrodynamic response of fish cage under extreme waves. Focused waves based on the NewWave theory are simulated to represent such extreme waves in this study. Based on the lumped-mass model, the fish cage is numerically simulated to analyze the motion and load characteristics in extreme waves. The results indicate that the fish cage volume dramatically decreases in extreme waves. The extreme wave results in large motions and mooring loads. Different extreme wave crest locations give rise to different net cage responses. The fish cage attacked at the leeward side suffers from larger motions and mooring loads than the upwind side. With the increase of the steepness, surge motions and mooring loads sharply increase. The preceding waves before the highest crest greatly influence the peak values of motions and loads. Results imply that not only the crest location but also the load histories should be carefully examined when investigating the extreme response.