Systematic model tests on centre bow design for motion and slamming load alleviation in high speed catamarans

While the unique centre bow of the Incat wave piercing catamaran (WPC) has evolved and improved over successive generations, it is of interest to more systematically evaluate its geometry against a variety of criteria including motions, loads, kinematics and slamming. A 2.5 m hydroelastic model with five alternate configurations of centre bow length and wetdeck vertical clearance was tested in regular waves. Both heave and pitch response amplitudes increased as the wet-deck height increased, while the length of the centre bow had less effect. However, the longer centre bow showed less heave amplitude at the heave resonance. Increasing the length of centre bow, however, consistently increased the slamming load severity, resulting in higher slam-induced bending moments, but the severity of local slamming pressures was not significantly affected. Increase of wet-deck height was more beneficial for reduction of slam loads and vertical bending moments than slam pressure. This suggests that redesigning the cross sectional arch configuration would be a suitable approach for alleviating slam pressure.