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

Lift coefficient

Optional number. Lift coefficient of the sail planform.

Sail area (m2)

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

Wind speed (m/s)

Required number in m/s. Apparent wind speed across the sail.

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

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. Inputs are interpreted exactly in the displayed units and the calculation returns the following fields without presentation rounding.

Sail force (N)

Returned number in N. Force exerted on the sail by the wind.

• 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.
• Lift coefficient must be at least 0.
• Lift coefficient must be no greater than 2.
• Sail area must be at least 0.
• 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.

• Sail Load Calculator

  Estimate the aerodynamic load on a sail from wind speed and sail area using a flat-plate drag model.

• Apparent Temperature Calculator

  Compute the simplified apparent temperature from air temperature, humidity-derived vapour pressure, and wind speed. With wind omitted, the result represents still air.

• Keel Lift Calculator

  Compute the hydrodynamic lift generated by a keel from boat speed, keel area, and a lift coefficient.