Characteristics of Wave Groups for the Evaluation of Ship Response in Irregular Seas

Abstract

A method to evaluate ship response in heavy seas is presented. A ship maneuvering in a stochastic environment is difficult to model because of the rarity and significant nonlinearity of the large motion responses. In the proposed method, critical wave groups are defined and used to separate the complexity of the nonlinear dynamics of ship response from the complexities of a probabilistic description for the response. In this formulation, wave groups may be considered as a possible method to solve the problem of rarity. With the characteristic information about the wave groups, the problem of rarity can be solved in a deterministic manner. Characteristics, including the distributions for the number of waves in a group and wave amplitude, period, and steepness for the waves in a group are presented.