Use this sailing calculation for planning or education when the vessel, units, reference directions, environmental conditions, and assumptions are explicitly known.

Wind speed (kt)

Required number in kt. Sustained wind speed to test against the storm threshold.

The cited overview of Maritime safety supplies background for the terminology and domain context used by this tool.^[1]

Check whether a wind speed in knots reaches storm force, meaning Beaufort force ten to eleven between forty-eight and sixty-four knots. Inputs are interpreted exactly in the displayed units and the calculation returns the following fields without presentation rounding.

Storm force

Returned boolean. True when the wind speed is storm force but below hurricane force.

• Vessel design and loading, sea state, wind, current, tide datum, weather, chart accuracy, equipment, crew, and safety margins can make real conditions differ from a simplified result.
• Wind speed must be at least 0.
• Use finite inputs in the displayed units, preserve source measurements and assumptions, and independently verify consequential decisions.

Cross-check current charts, tide and weather services, instrument data, vessel manuals, and applicable navigation rules, and retain a conservative alternative plan.

• 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.

• Beaufort Scale Lookup

  Look up the Beaufort wind force from zero to twelve for a wind speed in knots using standard inclusive upper bounds.

• Heel Target Guide

  Guide the upwind heel angle as eight tenths of the wind speed in degrees, clamped between five and thirty degrees.