The Beaufort Scale
Wind speed is measured in nautical miles per hour or ‘knots’ (1 nautical mile equals 1,853.27m or 1.15 statute miles). Knots are divided into wind forces, using a system invented by Admiral Beaufort in the 1700’s to describe likely conditions on the open
ocean and are still used for the daily shipping forecasts. The description of the sea state will generally be less severe for dinghy sailing in protected inshore waters, although coastal tides may create a sea state that is considerably more dangerous.