Use this sailing calculation as a planning or educational cross-check for navigation, wind and current, rig loads, stability, anchoring, tides, visibility, performance, or recovery under explicitly stated conditions.

TWS (kt)

True wind speed.

Boat speed (kt)

Boat speed through the water.

TWA (°)

True wind angle relative to the bow.

Compute the apparent wind angle from true wind speed, boat speed, and true wind angle. The tool evaluates the supplied inputs together and returns the named outputs below; it does not infer omitted operating conditions or change the units shown.^[1]

AWA (°)

Apparent wind angle relative to the bow.

• Actual conditions change with vessel design and loading, sea state, wind, current, tide datum, weather, chart accuracy, equipment, crew, regulations, and safety margins. Simplified formulas do not replace seamanship, approved stability data, or current navigation information.
• Use finite inputs in the displayed units and preserve more precision than the final presentation requires. Independently verify safety-critical, financial, compliance, or production decisions.

Cross-check official charts, tide and weather services, instrument data, vessel manuals, and collision regulations; maintain conservative margins and a safe alternative plan.

• Apparent Wind Speed Calculator

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

• Lee Bow Effect Calculator

  Project current onto the desired course as current speed times the cosine of the relative angle. This along-course proxy does not model the true lee-bow effect, which also depends on heading, boat speed, and apparent wind.

• True Wind Angle Calculator

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