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.

Elapsed time (min)

Minutes elapsed since the person went overboard.

Current (kt)

Current strength at the drift position.

Wind (kt)

Wind speed driving windage drift.

Windage factor

Fraction of the wind speed converted to drift per hour of exposure.

Estimate the maximum down-drift distance when current and windage act in the same direction. Vector set and wind directions are required for a position estimate. 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]

Drift distance (NM)

Distance between the casualty and the starting position.

• 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.

• Crew Drift Estimate

  Estimate how far an overboard crew member drifts as current speed times time in the water plus wind speed times time scaled by a one percent windage coefficient.

• Quickstop Return Course

  Calculate the reciprocal of the course at a man-overboard incident as a planning reference for the return leg. The actual Quickstop maneuver and final approach depend on wind, sea room, and the casualty's observed position.

• Set and Drift Correction Calculator

  Calculate current set and drift by subtracting the vessel's through-water velocity vector from its observed over-ground velocity vector.