Energy method augmented by phase trajectory analysis for estimating rolling damping of ships

The phase trajectory analysis is introduced into the energy method for better angle damping estimate, in turn, the better roll motion prediction of a ship. The model test data are collected in the same way of the conventional energy method and processed with phase trajectory analysis for extracting amplitude information. A law of rolling amplitude decaying is determined through data fitting. The calculated rolling damping is verified through simulation with linear-plus-square damping moment model. The accuracy improvement gained by the method is demonstrated.