Sailboat Calculators

Calculator Formula Inputs
Sail Area / Displacement Ratio

A measure of the power of the sails relative to the weight of the boat. The higher the number, the higher the performance, but the harder the boat will be to handle.

SA / (Disp / 64)^(2/3) Sail Area, Displacement
Ballast / Displacement Ratio

A measure of the stiffness and power of a boat. Predicts the ability of a boat to stand up to the wind.

Bal / Disp × 100 Ballast, Displacement
Displacement / Length Ratio

A measure of the ability of a boat to reach nominal hull speed.

(Disp / 2240) / (0.01 × LWL)³ Displacement, Waterline Length
Comfort Ratio

A measure of motion comfort. Generally, the faster the motion, the more jarring/uncomfortable the ride.

Disp / (0.65 × (0.7 × LWL + 0.3 × LOA) × Beam^1.33) Displacement, Waterline Length, Length Overall, Beam
Capsize Screening Ratio

A measure of the bluewater capabilities of a boat.

Beam / (Disp / 64)^(1/3) Beam, Displacement
Estimated Hull Speed

The theoretical maximum speed of a displacement hull.

1.34 × √LWL Waterline Length
Performance Calculator

Compute all performance ratios at once.

All All dimensions
Sail Calculator

Calculate sail areas from sail plan dimensions.

½ × base × height I, J, P, E, PY, EY