Sailboat Heeling Angle Calculator
Estimate a sailboat heeling angle from wind pressure and righting moment.
Understand the stability trade-off for different sail configurations.
A sailboat heels (tilts sideways) when the heeling force from the sails exceeds the boat’s initial righting moment. The angle of heel is a function of wind force on the sails and the boat’s stability characteristics.
Simplified formula: Heel angle ≈ arctan(Heeling Moment / Righting Moment) Heeling Moment = Wind force × Center of Effort height above waterline Righting Moment = Displacement × GM × sin(heel) (for small angles: RM ≈ Δ × GM × heel_rad)
Wind pressure on sails: P = 0.00338 × V² (lbs/ft² where V is apparent wind in knots) Heeling Force = P × Sail Area × sin(apparent wind angle)
Metacentric height (GM): Determines initial stability. Typical values:
- Narrow, deep-keeled racer: GM = 0.8–1.2 m (tender but fast)
- Cruising yacht: GM = 1.5–2.0 m (stiffer, more comfortable)
- Heavy cruiser: GM = 2.0–3.0 m (very stiff, more motion)
Comfort ranges:
- 0–15°: Very comfortable, easy sailing
- 15–25°: Normal sailing angle, some items may slide
- 25–35°: Uncomfortable for novices, reduce sail
- Over 35°: Excessive, dangerous — reef immediately
Practical note: Modern offshore racing yachts regularly sail at 20–25° heel for speed. Cruising sailors typically prefer 15–20°. More than 30° sustained heel suggests too much sail for conditions.
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