The assessment of ship’s damage stability in waves by testing a series of damage scenarios is nowadays accepted both scientifically as well as in relevant SOLAS regulations (performance based stability standards). Numerical simulation methods assisting the above procedure may significantly enhance the overall assessment efficiency. The main objective of these procedures is the prediction of ship motions and instabilities in extreme seaway excitation. Obviously, when validating such a simulation method, the flooded ship dynamics in stable conditions should be firstly ensured before concluding on the suitability of the method in marginal cases, where instability can occur.

In this paper the behaviour of a damaged Ro-Ro ship model with water on car deck in beam waves was investigated, both numerically and experimentally. The experimental ship model was restrained to only allow three degrees of freedom motions, namely that sway, heave and roll. This restriction ensured increased control of the experimental parameters and repeatability of the model experimental results. Steady state conditions of the flooded ship model motions in regular and irregular waves were achieved and a comprehensive comparison between numerical results and experimental measurements was carried out providing satisfactory results.