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

Wind speed (m/s)

Required number in m/s. True wind speed.

Sail area (m²)

Required number in m². Total sail area exposed to the wind.

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

Estimate the aerodynamic load on a sail from wind speed and sail area using a flat-plate drag model. Inputs are interpreted exactly in the displayed units and the calculation returns the following fields without presentation rounding.

Sail load (N)

Returned number in N. Estimated load on the sail.

• 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.
• 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.

• Wind Pressure on Sail Calculator

  Compute aerodynamic force on a sail from dynamic pressure using 0.5 times air density times wind speed squared times sail area times lift coefficient.

• Mooring Windage Load Calculator

  Compute the wind load on a moored vessel from wind speed, windage area, and drag coefficient.

• Spinnaker Area Calculator

  Estimate the symmetric spinnaker area from the SL leech length and SMW width using the standard three-quarter approximation.