Use this sailing calculation as a planning or educational cross-check for navigation, wind and current, rig loads, stability, anchoring, tides, visibility, performance, or recovery under explicitly stated conditions.

Wind speed (kt)

Wind speed to classify on the Beaufort scale.

Look up the Beaufort wind force from zero to twelve for a wind speed in knots using standard inclusive upper bounds. The tool evaluates the supplied inputs together and returns the named outputs below; it does not infer omitted operating conditions or change the units shown.^[1]

Beaufort force

Beaufort force from zero (calm) through twelve (hurricane).

• Actual conditions change with vessel design and loading, sea state, wind, current, tide datum, weather, chart accuracy, equipment, crew, regulations, and safety margins. Simplified formulas do not replace seamanship, approved stability data, or current navigation information.
• Use finite inputs in the displayed units and preserve more precision than the final presentation requires. Independently verify safety-critical, financial, compliance, or production decisions.

Cross-check official charts, tide and weather services, instrument data, vessel manuals, and collision regulations; maintain conservative margins and a safe alternative plan.

• Douglas Sea State Lookup

  Look up the Douglas sea state from zero to nine for a significant wave height in meters using standard inclusive upper bounds.

• Gale Warning Check

  Check whether a wind speed in knots reaches gale force, meaning Beaufort force eight to nine between thirty-four and forty-eight knots.

• Storm Warning Check

  Check whether a wind speed in knots reaches storm force, meaning Beaufort force ten to eleven between forty-eight and sixty-four knots.