A study on the effect of parametric roll on added resistance in regular head seas

Both parametric roll and added resistance in head seas are hot topics in ship hydrodynamics. Parametric roll with half the encounter frequency is usually not taken into account in the calculation of added resistance in regular head seas. In order to study the correlation between parametric roll and added resistance, firstly, a formula of added resistance in regular head seas with parametric roll taken into account based on Maruo theory is developed to investigate the effect of parametric roll on added resistance in regular head seas. Secondly, partially restrained free running experiments with and without roll motions are carried out respectively to investigate the effects of parametric roll on added resistance in regular head seas. The results of experiments and simulations using the C11 containership show that added resistance is affected by parametric roll, and the results of experiments also show that heave and pitch motions are distinctly affected by parametric roll.