A model of significant wave height for reliability assessment of a ship

•Means to describe variability of encountered sea states by a vessel are given.•A simple model for significant wave heights variability is proposed.•The model features a small number of parameters with simple physical interpretation.•The damage accumulated in a vessel details and its variability are assessed.•The Rice method yields prediction of the extreme seas encountered by a ship.

Significant wave heights are modeled by means of a spatial-temporal random Gaussian field. Its dependent structure can be localized by introduction of time and space dependent parameters in the spectrum. The model has the advantage of having a relatively small number of parameters. These parameters have natural physical interpretation and are statistically fitted to represent variability of observed significant wave height records. The fitted spatial-temporal significant wave field allows for prediction of fatigue accumulation in ship details and of extreme responses encountered. The method is exemplified by analyzing a container ship data relevant for North Atlantic trade and the results show a high agreement with actual on-board measurements.