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.

Reference height (m)

Vertical distance from the lower measurement point to the masthead.

Rake (mm)

Horizontal rake offset measured from mast head to a plumb line at the boom.

Compute mast rake from the horizontal masthead offset and the vertical distance between the masthead and the lower measurement point. 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]

Rake angle (deg)

Rake angle of the mast relative to vertical.

• 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.

• Distance to Layline Calculator

  Calculate the distance along the course centerline to a layline from the lateral offset and half of the total angle between port and starboard tacks.

• Vang Angle Calculator

  Compute the vang angle in degrees as atan of the mast attachment height over the boom attachment distance.

• Layline Distance Calculator

  Compute the distance along a layline to the mark given the lateral offset and tack angle.