Abstract
A time-domain numerical simulation method is applied for the investigation of parametric roll resonance in regular head waves for two different types of vessels, namely a fishing vessel and a RoRo ship. The employed mathematical model captures satisfactorily most of the parameters relevant to the problem hence enables an improved reproduction and understanding of the complicated non-linear parametric roll phenomenon. The coupling between the induced roll and pitch motions along with the nonlinear character of the restoring moment associated with large amplitude wave induced motions have been found to be the determinant factors of the observed roll resonance phenomenon. Furthermore, a strong dependence of the roll resonance on both the wave frequency of encounter and the incident wave height has been recorded. The obtained numerical results were compared with corresponding available experimental measurements and commented.