Slamming response of a large high-speed wave-piercer catamaran

Commercial and military requirements for high-speed sea transportation has led to the evolution of large, fast, lightweight vessels. Knowledge of the effect of sea loads on the structure of such vessels is required in order to carry out structural design optimization. Wet deck slam events, which occur when the vessel's motion causes an impact between the cross-deck structure and the water surface when operating in large waves, are of particular importance for high-speed catamarans. Extensive full-scale hull stress, motion, and wave measurements have been conducted on an 86-m Incat high-speed catamaran ferry during a delivery voyage. A definition of a slam event, for this vessel, is proposed and used to identify slam events from the data records. The character and effects of these slamming events are investigated with respect to a number of factors, including structural loading, wave height and length, vessel speed and heading angle,relative vertical velocity, and frequency ofoccurrence. The results of the full-scaledata analysis are presented. Particular attention is paid to thewhipping response of the structure, with the principal structural response frequencies being identified through spectral analysis.