Characterisation of slam events of a high-speed catamaran in irregular waves

A hydroelastic segmented model of a wave-piercer catamaran has been designed and constructed for obtaining experimental values of global and slamming loads. The model was extensively instrumented with strain gauges, pressure transducers, LVDTs and a series of wave probes. It was tested in irregular head seas, for a variety of significant wave heights and modal periods. For the conditions tested, slam occurrence rates show an increase in slam rate with a rise in wave height but a reduction with an increase in speed. In all conditions a range of slam magnitudes was seen, with the majority of slam events being of low severity. Slam events are characterised according to a range of parameters, revealing that the majority of slams occurred within the bow reaching 20% of the wave length before the wave peak. The height of the back of the preceding wave has more influence on the slam magnitude that the face height of the wave into which the vessel slams and the majority ofthe peak slam pressures were located in the vicinity of the centre bow truncation and further aft.The relative vertical velocity at impact tended to correlate with the slam magnitude.