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

Apparent wind (kn)

Required number in kn. Apparent wind speed between 0 and 40 knots.

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

Suggest traveler position from offsetCm = min(30, max(-30, round((15 - apparentWindKt) * 2))); positive values are to weather. Inputs are interpreted exactly in the displayed units and the calculation returns the following fields without presentation rounding.

Traveler offset (cm)

Returned number in cm. Signed traveler offset in centimeters; positive means to weather.

• 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.
• Apparent wind must be at least 0.
• Apparent wind must be no greater than 40.
• 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.

• Backstay Tension Guide

  Suggest backstay tension from backstayPercent = min(100, max(10, round(apparentWindKt * 4))).

• Cunningham Tension Guide

  Suggest cunningham tension from cunninghamPercent = min(100, max(0, round((apparentWindKt - 8) * 6))).

• Jib Lead Angle Guide

  Suggest jib lead angle from leadAngleDegrees = min(25, max(5, round(apparentWindKt * 0.8))).