Sea State

Sea state is the overall condition of the sea surface affecting a vessel, described by the mix of local wind waves, swell, height, period, direction and steepness. In marine forecasts it is commonly summarised as significant wave height, but the same height can feel very different depending on wave spacing and angle to the boat.

For boaters, sea state influences comfort, speed, fuel use, crew fatigue and safety margins. Short, steep seas may cause slamming or green water on deck, while long swell can create rolling at anchor or difficult bar crossings. Key inputs include Wave Height, Wave Period and situations such as Wind against Current.

PredictWind Wave Maps, forecast tables and Weather Routing help assess sea state along a planned track, not just at departure. Comparing model guidance and swell components supports safer departure choices, improved routing, and better expectations for onboard motion and performance.