The study of motion of ships or similar slender offshore structures in irregular seas has, in recent years, gathered sufficient interest due to the fact that experimental data and various approximate techniques are readily available, and that ship safety is a much more expensive issue. Central to the study is the problem of predicting ship rolling motion due to random waves. In this paper a method, employing the statistical non-linearization technique that was developed by the author, is applied to evaluate the joint stationary probability density of response of a model proposed by Roberts and associates for the analysis of nonlinear ship rolling in random seas. For small nonlinear damping and small intensity of excitation the result is identical to that obtained with the generalized stochastic averaging method of energy envelope presented earlier by the author.
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