Comparison of wind and wave climate in open sea and coastal waters

Wind and wave climate is much geographical region and location dependent, affected by local properties of ocean environment. For safety of world-wide sailing ships knowledge about wind and wave conditions is important, not only for open sea, but also in coastal areas. Wind and waves impact ship design, marine operations and they challenge ability of ships to maintain manoeuvrability in sea states. Their characteristics differ in open sea and coastal waters, and recently have got attention within the maritime community due to the issue of the 2013 Interim Guidelines by IMO (International Maritime Organization) where adverse weather conditions to be used in assessment of ship manoeuvrability have been proposed. The present study investigates how realistic the proposed weather conditions are using data from selected ocean locations. It compares open sea and coastal water wind and wave climate applying hindcast data in the analysis. The description of open sea metocean conditions is limited to the North Atlantic while European waters are used as representative for coastal regions. Challenges in providing metocean description for assessment of ship manoeuvrability are discussed and three approaches for doing it are proposed, giving attention to associated uncertainties. The established correlations between wind speed and significant wave height as well as significant wave height and spectral peak period are compared with the ones suggested by the 2013 Interim Guidelines and other existing standards.