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

Maximum heading (°)

Required number in °. Largest heading observed during the oscillation.

Minimum heading (°)

Required number in °. Smallest heading observed during the oscillation.

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

Compute half the shortest circular separation between the two extreme compass headings, including oscillations that cross north. Inputs are interpreted exactly in the displayed units and the calculation returns the following fields without presentation rounding.

Amplitude (°)

Returned number in °. Half of the heading spread covered by the oscillation.

• 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.
• Maximum heading must be at least 0.
• Maximum heading must be no greater than 360.
• Minimum heading must be at least 0.
• Minimum heading must be no greater than 360.
• 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.

• Shift Rate Calculator

  Compute the signed rate of the shortest compass-direction change between two mean wind headings, correctly handling the wrap across north.

• Upwind TWA Guide

  Guide the upwind target true wind angle as forty five degrees minus half the wind speed, clamped between thirty and fifty five degrees.

• Apparent Wind Angle Calculator

  Compute the apparent wind angle from true wind speed, boat speed, and true wind angle.