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ABSTRACT

The probabilistic prediction of crest heights of sea waves based on the Rayleigh distribution can significantly underestimate actual crest heights associated with large waves of design interest. In theory, the Rayleigh distribution is appropriate to linear waves characterized by a vertical crest-to-trough symmetry, In practice, large waves tend to be nonlinear and vertically asymmetrical in terms of higher, more pointed crests and shallower, more rounded troughs. Herein, a simple second-order nonlinear model is used to derive a theoretical Exceedance distribution that serves as an upper bound to the distribution of crest heights of large waves. The salient features of this distribution are discussed and compared with observed distributions of large waves gathered under hurricane conditions. The results show that the new distribution for the crest heights of large waves compares with observational data favorably as an upper-bound limit.