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

Mainsail area (m²)

Required number in m². Measured area of the mainsail.

Sheet angle (deg)

Required number in deg. Included angle between sheet and boom at the clew, greater than 5 and less than 90 degrees.

Wind speed (m/s)

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

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

Estimate the main sheet load from dynamic pressure on the sail area divided by the sine of the sheet angle. Inputs are interpreted exactly in the displayed units and the calculation returns the following fields without presentation rounding.

Sheet load (N)

Returned number in N. Tension carried by the main sheet.

• 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.
• Sheet angle must be at least 5.
• Sheet angle must be no greater than 90.
• 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.

• Jib Sheet Load Calculator

  Estimate the jib sheet load from dynamic pressure on the sail area divided by the sine of the sheet angle.

• Sail Load Calculator

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

• 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.