Enhancing passenger comfort in high-speed Catamarans: An experimental study of ride control systems in irregular waves

To minimise motion sickness in high-speed catamarans and improve passenger comfort, ship designers require a thorough understanding of the Ride Control System (RCS). In this paper, the influence of various ride control algorithms on motion sickness on board a 112 m Incat Tasmania high-speed catamaran was investigated using frequency and time domain analyses of experimental data from towing tank tests conducted on a 2.5 m scaled model in irregular head sea waves. The RCS consisted of two stern-mounted transom tabs and a bow-fitted T-Foil. Frequency-domain analyses evaluated vertical acceleration spectra at three longitudinal locations to calculate Motion Sickness Dose Value (MSDV) based on the ISO 2631 standard. Time-domain analyses assessed the impact of the RCS and various algorithms on the probability and magnitude distribution of extremum accelerations and the duration of exposures to different acceleration levels. Cumulative MSDV trends, calculated across diverse conditions at three locations, were modelled using power functions and validated against frequency-domain MSDV values for 60-min exposures. The mathematical models demonstrated reliable predictive capability for extended-duration assessments, offering a powerful tool for optimising RCS activation to balance passenger comfort and energy efficiency. Results of this dual-domain analysis revealed the highest motion sickness at the bow and the lowest at the midship. A nonlinear pitch control algorithm reduced RMS vertical accelerations and MSDV at the bow by up to 41 % and 70 % in moderate waves, and 32 % and 54 % in large waves, respectively, which demonstrates significant improvement in passenger comfort. Alternatively, expressed in terms of the time domain analysis findings, deployment of the nonlinear pitch RCS enables passengers to travel 10 times longer before experiencing the equivalent level of motion sickness. Finally, specific operational needs of a ship are shown to affect which motions should be prioritised for reduction, affecting the choice of optimum algorithm.