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.

Keel draft (m)

Mean draft of the keel below the hull.

Keel area (m²)

Projected area of the keel.

Compute the keel aspect ratio as keelAspectRatio = draftMeters^2 / keelAreaM2; deep fin keels have high ratios. 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]

Keel aspect ratio

Aspect ratio of the keel planform.

• 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.

• Rudder Aspect Ratio

  Compute the rudder aspect ratio as rudderAspectRatio = depthMeters^2 / rudderAreaM2; high ratio rudders are deep and narrow.

• Main Aspect Ratio

  Compute the mainsail aspect ratio as aspectRatio = luffLengthMeters^2 / mainsailAreaM2; taller narrower sails have higher ratios.

• Jib Aspect Ratio

  Compute the jib aspect ratio as aspectRatio = iMeasurementMeters^2 / jibAreaM2 using the forestay height I and the measured jib area.