Slamming Incidence

Slamming incidence is the frequency or likelihood of a vessel’s hull striking the water with a hard impact after becoming partially unsupported by waves. It is most often felt as bow or forward hull pounding when a boat drops off a wave face, meets steep chop, or runs too fast for the conditions.

For boaters, high slamming incidence means more crew fatigue, reduced speed over ground, greater risk to fittings, electronics and structure, and a higher chance of injury on deck. It is influenced by Wave Height, Wave Period, hull form, loading and speed; a short, steep Sea State is often worse than a longer ocean swell. Skippers reduce it by slowing down, changing heading, redistributing weight or delaying departure.

PredictWind wave forecasts, model comparisons and route tools help identify areas where slamming is likely before you commit to a passage. In Weather Routing, selecting a route or departure time that avoids steep head seas can protect the boat, preserve comfort and maintain more realistic passage speeds.