The Roll Damping of High-Speed Craft in Waves

The main component of high-speed craft (HSC) roll damping is related to the hydrodynamic lift developed on the hull surface. This is very different from displacement type hull forms. However, the estimation of roll damping of HSC is often treated in the same manner as for larger and slower ships. Being able to model the roll of HSC correctly is of paramount importance in the prediction of the lateral component of acceleration of an impact at a roll angle in waves, or during a manoeuvre at high speed. These are phenomena that can have severe consequences on the comfort and safety of the crew on-board of HSC. Three procedures meant to estimate the HSC roll damping were analyzed. The outcomes of these procedures were compared in terms of roll and lateral accelerations statistics of HSC sailing in irregular waves. The HSC motions were predicted by a 2D+t mathematical model. Differently from the majority of the state-of-art HSC seakeeping tools, which focuses only on the vertical impacts in head waves, in this work the roll was included in the simulations. The numerical results of the simulations were validated by means of free sailing model tests at beam and quartering irregular seas carried out at the Seakeeping and Manoeuvring Basin of MARIN.