Use this sailing calculation for planning or education when the vessel, units, reference directions, environmental conditions, and assumptions are explicitly known.

Distance to layline (NM)

Required number in NM. Distance to the layline measured on the water.

VMG (kt)

Required number in kt. Velocity made good toward the layline.

The cited overview of Sailing supplies background for the terminology and domain context used by this tool.^[1]

Estimate the minutes remaining to the layline by dividing the current corrected distance to the layline by the velocity made good and converting to minutes. Inputs are interpreted exactly in the displayed units and the calculation returns the following fields without presentation rounding.

Time to layline (min)

Returned number in min. Minutes until the boat lays the mark approach.

• Vessel design and loading, sea state, wind, current, tide datum, weather, chart accuracy, equipment, crew, and safety margins can make real conditions differ from a simplified result.
• Use finite inputs in the displayed units, preserve source measurements and assumptions, and independently verify consequential decisions.

Cross-check current charts, tide and weather services, instrument data, vessel manuals, and applicable navigation rules, and retain a conservative alternative plan.

• Time to Start Line Calculator

  Calculate how many minutes it takes to reach the start line from the remaining distance and current boat speed.

• 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.

• 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.