Slam loads and pressures acting on high-speed wave-piercing catamarans in regular waves

Slamming loads and pressures on high-speed catamarans with a centre bow (CB) differ from those on conventional catamarans with flat deck structures. The latter are well covered by class rules, which provide empirical formulae to calculate the design slamming pressure. An experimental study was therefore performed to quantify slamming pressures in the archways between bow and main hulls and the CB slamming force on a 112m wave piercing catamaran. The CB length was systematically varied on a 2.5m hydroelastic segmented catamaran model, which was tested in regular head sea waves at a speed of 2.89 m/s, full-scale equivalent of 38 knots. Slamming pressures were measured by 18 pressure transducers fitted into the CB, while data obtained from CB accelerometers and load cells enabled identification of the slamming force. The results indicate that slamming loads increase significantly with increasing CB length while the maximum peak slamming pressures varies to a lesser extent. It was also found that wave encounter frequency has a strong effect on the location of maximum pressure along the CB, considerably more so than any influence of CB configuration. The distribution of the peak pressures within the CB archway shows that the inboard peak pressures are larger than those at the top of the arch and the outboard locations.