Numerical Simulation of Motion Responses of a Cabin-Suspended Catamaran in Head Waves

Abstract In this study, the motion responses of a suspension catamaran in head waves are presented using numerical calculation and experimental validation. The cabin-suspended ship has 9 degree-of-freedom, as the heave, pitch, and roll motion of the cabin can be separated from that of the twin-hull through a suspension unit. The suspension unit consists of four compression springs and linkages to guide the motion. The hydrodynamic coefficients and the wave exciting force/moments of the twin-hull were calculated using a potential flow solver named OrcaWave. A method was proposed to approximate the wave exciting force/moments at an advancing speed using the wave exciting force/moments at zero speed. The study analyzed the motion response of the ship at different damping coefficients and spring constants. The results show that motion reduction of the cabin by tuning only the spring constant and damping coefficient is limited, and different pairs of spring constant and damping coefficient would be needed for different wave encounter frequencies. The study provides valuable insights for the design of suspension ships to reduce motion responses in head waves.