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

Heel angle (deg)

Required number in deg. Angle of heel from upright.

Metacentric height (ft)

Required number in ft. Metacentric height GM of the vessel.

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

Approximate the initial-stability righting arm as GZ = GM sin(heel) for heel angles no greater than fifteen degrees; use a vessel's measured GZ curve at larger angles. Inputs are interpreted exactly in the displayed units and the calculation returns the following fields without presentation rounding.

Righting arm (ft)

Returned number in ft. Righting arm GZ at the given heel angle.

• 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.
• Heel angle must be at least 0.
• Heel angle must be no greater than 15.
• 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.

• Leeway Angle Calculator

  Estimate leeway angle with the empirical relation leeway = K times heel divided by boat speed squared. Calibrate K for the hull, keel, and knot-based speed data in use.

• Anderson Turn Course

  Calculate the return course reached by an Anderson turn, which rotates the heading two hundred forty degrees toward the chosen turn direction to bring the vessel back along its original track.

• Code Zero Wind Angle

  Estimate the true wind angle for a code zero using codeZeroTwaDeg = round(50 + apparentWindKt * 0.3), clamped to 40 through 70 degrees.