Mitigating load responses of high-speed catamarans via ride control systems: An experimental study in irregular waves, part1: Slam events

• A 2.5 m hydroelastic segmented catamaran model was tested in irregular waves. • Model fitted with a ride control system comprising two stern tabs and a T-Foil. • Nonlinear pitch control (NPC) algorithm mitigated slam occurrence by 96%. • Maximum slam magnitude was reduced by 70% using NPC algorithm. • NPC algorithm reduced maximum slam-induced sagging bending moments by 66%. This study aims to investigate the influence of a Ride Control System (RCS) on the load responses of a 2.5 m hydroelastic segmented catamaran model, which represents a 112 m high-speed catamaran. The efficacy of different control algorithms in mitigating slam rates and magnitudes was quantified by comparing results with those obtained for a bare hull with the No RCS control mode. Towing tank experiments were conducted in irregular head seas with a forward speed of 2.89 m/s (37 knots full-scale) at two significant wave heights. The results revealed that the nonlinear pitch control algorithm was the most efficient, achieving an impressive 96% reduction in slam occurrence, a 70% reduction in maximum slam magnitude, and a 66% reduction in maximum slam-induced sagging bending moments in moderate waves. Additionally, it was revealed that increases in wave height elevated the probability of slams, amplified variance in the distribution of slam loads and slam-induced bending moments and reduced the influence of the RCS in mitigating structural loads on the catamaran model. It was shown that irregular sea slam responses can be predicted from regular sea data, based on regular tests at a frequency corresponding to the modal period of the irregular sea case, with an accuracy of within 8 % for moderate waves and within 15 % at large waves.