Time Domain Analysis on Ship Maneuvering in Adverse Sea State

Energy Efficiency Design Index (EEDI) introduced by the IMO Resolution MEPC.203 (62) has been the first initiative to regulate the greenhouse gas (GHG) emissions from ships. However, it has raised serious concerns that some ship designers might choose to lower the installed power to achieve EEDI requirements not accounting satisfactorily for ship safety. This has encouraged investigations addressing the ability of ship to maintain maneuverability in adverse sea states. The Interim Guidelines proposed in 2013, in IMO Res. MEPC.232 (65), recommend minimum propulsion power to maintain ship maneuvering ability in adverse weather conditions for bulk carriers and tankers. These guidelines are mainly based on statistical analysis and equilibrium analysis in a steady state. Today, most of the available tools and methods handle ship responses in waves by separating it into seakeeping and maneuvering. The present study investigates ship maneuverability by use of a recently developed time domain code which combines the sea-keeping and maneuvering equation to predict ship responses in waves. In this way, better insight into ship responses in adverse conditions is obtained. The numerical results presented in the study are validated by model tests. The limitations of the time-domain code are discussed and future research needs are pointed out.