Piston Mode and Sloshing Resonances in a Damaged Ship

This work investigates the motions of a damaged ship in regular beam sea waves. The ship geometry including the damaged compartment (with opening) is modeled by using a unified approach called Hull Reshaped Method [1] and the hydrodynamic problem is solved by applying a 3D potential flow code. Linear hydrodynamic coefficients and excitation loads together with experimental nonlinear viscous roll damping are used in the calculations of the motion response functions. In addition to the natural roll resonance, the piston mode and sloshing resonances are numerically observed. By applying simplified theoretical analysis, these two resonances are further confirmed for a damaged ship with opening in the hull defined by the SOLAS rule [2]. The resulting physical problems, for instance, dry bottom, roof impact and possible structural failure in the damaged compartment are predicted from the simulations.