Slamming and Whipping of Wave-Piercing Catamarans

Wavelet analysis identifies slamming events during sea trials. Maximum loads, load impulses and energy imparted to the structure by slams have been evaluated. A segmented hydro-elastic model has been developed to simulate the main whipping mode, elastic links in the model facilitating measurement of bending moments and determination of slam loads. Slams of up to 2200 tonnes peak force can occur when the wet deck arches between the main hulls and centre bow fill, imparting impulses of up to 938 tonne seconds and 3.5 MJ of strain energy. Energy is transferred to the whipping mode which has a damping ratio in the range 0.02 to 0.06 depending upon forward speed.