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.

Lateral offset (nm)

Perpendicular distance from the course to the mark; may be zero or negative for either side.

Tacking angle (deg)

Total angle between the port- and starboard-tack courses.

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. 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]

Distance to layline (nm)

Straight-line distance along the course to the layline.

• 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.

• Layline Distance Calculator

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

• Current Gain Loss Calculator

  Calculate the distance gained or lost to the current along the course, with a favorable set positive and an adverse set negative.

• EP With Leeway

  Estimate the course made good by applying leeway to the true heading, subtracting the leeway angle on the starboard tack and adding it on the port tack.