On Fully Describing the Probability Distribution of Quiescent Periods From Sea Spectral Density

A fundamental property of most sea conditions is that sets of large waves alternate with sets of smaller waves, known as quiescent periods. Exploiting the quiescent periods can expand the sea states under which the execution of many maritime operations can be considered safe. Building upon the work of Belmont et al., we extend the methodology to fully describe the statistical distribution of the quiescent periods in terms of their time duration using sea spectra derived from current ship readings as well as metocean forecast. This provides the basis for a short- or long-term planning tool that complements deterministic wave prediction technology for executing wave-height-limited maritime operations. The method is evaluated using spectra calculated from field measurements in a dedicated sea trial and from standard parameterized oceanographic forms (JONSWAP and Pearson-Moskowitz).