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

AWS (kt)

Required number in kt. Apparent wind speed.

AWA (°)

Required number in °. Apparent wind angle relative to the bow.

Boat speed (kt)

Required number in kt. Boat speed through the water.

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

Compute the true wind angle from apparent wind angle, boat speed, and apparent wind speed. Inputs are interpreted exactly in the displayed units and the calculation returns the following fields without presentation rounding.

TWA (°)

Returned number in °. True wind angle relative to the bow.

• 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.
• AWS must be at least 0.
• AWA must be at least 0.
• AWA must be no greater than 180.
• Boat 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.

• Apparent Wind Angle Calculator

  Compute the apparent wind angle from true wind speed, boat speed, and true wind angle.

• Apparent Wind Speed Calculator

  Compute the apparent wind speed from true wind speed, boat speed, and true wind angle.

• True Wind Speed From Apparent Calculator

  Compute the true wind speed from apparent wind speed, apparent wind angle, and boat speed.