A numerical model of ship manoeuvring for the KVLCC2 hull, in regular and long-crested irregular waves

This paper addresses the development and application of a numerical simulation model for ship manoeuvring in waves. This topic is of considerable interest to accurately assess the overall dynamics of a vessel, in particular regarding the interactions among the hull, the propeller, and the engine behaviour. The dynamics of a ship turning in rough seas involves several complex phenomena, including the non-linear actions exerted by the waves on the hull and the various interactions between hull, propeller, waves, and rudder. The numerical simulation model presented in this research uses the so-called “direct superposition” approach, i.e. a hybrid approach that integrates the manoeuvring model in calm water, known as the Manoeuvring Modelling Group (MMG) model, with a mixed non-linear seakeeping model. To evaluate the accuracy and limitations of the proposed model, a benchmark ship, the KVLCC2, is used, for which extensive experimental data are available in the technical literature. A preliminary validation of the turning characteristics in calm water is provided, together with analyses of heave and pitch motions in head seas. Subsequently, turning circle simulations are conducted in both regular waves and irregular long-crested seas, and the results are compared with available experimental data. A generally favourable agreement of the results is observed. However, the limitations of the numerical simulation become more evident with subsequent turns performed by the ship. By restricting the comparison to the range of practical manoeuvres for a vessel at sea, the proposed model appears suitable for applications focused on control purposes.