THE INFLUENCE OF DESIGN CONSTRAINTS ON THE DAMAGE SURVIVABILITY OF RO-RO VESSELS

This paper examines the influence of key design characteristics on the damage survivability of ro-ro vessels in a random sea. The approach adopted in undertaking this study is briefly explained and the results of a parametric investigation, considering a representative vessel, are presented and discussed. The paper focuses on the effects of freeboard and the transverse subdivision above the bulkhead deck by considering the vessel in a number of loading conditions and sea states. Finally, the effect of retrofitting structural sponsons is assessed. Based on the results of the investigation boundary survival curves, involving relationships between ship design and environmental parameters and stability-related parameters are developed as a substitute to still water damage stability criteria. The two key conclusions from this research are: the 0.076m damaged freeboard, required by current regulations is unrealistically low and must be significantly increased before a ship can be considered safe in normal operating conditions; the undivided length of a compartment above the bulkhead deck may have to be as small as 25m to enable the vessel to survive in an extreme wave environment.