Experimental study of non-linear rolling of a fishing vessel in a regular beam sea

Scale model experiments of forced roll in a regular beam sea have been conducted on a large scale fishing vessel. A methodology for the stimation of roll equation parameters, based on linear least squares fitting of numerical solution of the roll motion equation to the experimental data has been developed and implemented in a computer code. The analysis of the experimental data allowed to obtain information of the different linear/non-linear damping contributions and on the effective wave slope coefficient. The conclusions highliht the validity of different damping models in simulating forced roll in waves. At the same time, the conclusion enforce the known problem of the dependency of the parameters on the frequency of the exitation.