Distribution of wave crests in non-Gaussian sea

The sea elevation at a fixed point is modelled as a quadratic form of a vector valued Gaussian process with arbitrary mean. An apparent wave is a part of the sea record observed between two successive upcrossings of the still water level. Saddlepoint methods are used to approximate the mean upcrossing intensity +(u), say, with which the sea level crosses upwards at height u. This estimated intensity is further used to determine the density of crest height. Several numerical examples are given.