Boat Speed Calculator

Crouch's formula calculates boat speed as: Speed = √(Horsepower ÷ Displacement) × Constant. This formula helps estimate a boat's theoretical top speed based on its power-to-weight ratio and a constant that varies by boat type.

The Crouch constant varies by boat type: Racing boats (280-300), High-speed runabouts (220-240), Light high-speed cruisers (190-210), Average runabouts (150-180), Cruisers (150-170), and Passenger vessels (150-160).

Displacement is the total weight of the boat including the hull, engine, fuel, gear, and passengers. It's measured in pounds and represents how much water the boat displaces when floating.

This calculator provides theoretical estimates based on Crouch's formula. Actual speeds may vary due to hull design, propeller efficiency, water conditions, and boat loading. It's best used for preliminary planning and comparisons.

Enter your boat's total weight (displacement), engine horsepower, and boat type. The calculator uses Crouch's formula to estimate top speed. For more accuracy, you can input a custom constant if known.

Actual boat speed depends on hull design, propeller pitch and diameter, water conditions, boat trim, weight distribution, and engine tuning. The calculator provides theoretical maximums under ideal conditions.

Yes, enter the total combined horsepower of all engines. For example, if you have twin 150 HP engines, enter 300 HP in the horsepower field.

Power-to-weight ratios vary by boat type. Racing boats may have 0.1+ HP/lb, while cruising boats typically have 0.02-0.05 HP/lb. Higher ratios generally mean higher potential speeds but also higher fuel consumption.