Mast Rake Calculator
Calculate mast rake angle from measurements.
Optimize helm balance by adjusting mast rake on your sailboat.
Mast rake is the angle the mast makes from vertical, measured forward or aft. Most sailboat masts rake slightly aft to improve helm balance and upwind performance.
Why mast rake matters:
- Aft rake moves the center of effort (CE) aft, reducing weather helm
- Forward rake moves CE forward, reducing lee helm (or increasing weather helm)
- Proper rake gives balanced, neutral-to-slight-weather helm — the ideal for safety and performance
Measuring mast rake: Hang a weight on a string (plumb bob) from the masthead. Measure the horizontal distance from where the string falls to the base of the mast. Rake = arctan(horizontal offset / mast height).
Typical rake values:
- Most fractional rig sloops: 1–3° aft
- Performance dinghies (Laser, 420): up to 5° aft for upwind, less for downwind
- Cat-rigged boats: often 3–5° aft
- Forward rake: unusual, corrects strong weather helm
Adjusting rake: Change the length of the forestay (in unstayed masts) or backstay tension (in stayed masts). Moving the mast step forward or aft also affects rake.
Helm balance check: Ideal is 3–5° of weather helm — the boat gently rounds up when you let go of the tiller. No helm (neutral) or lee helm (bears away) indicates CE is too far forward — more aft rake needed.