Hull Speed Calculator

Professional marine calculator for boat owners and marine engineers.

Need to know if your boat can outrun its own bow wave? Hull Speed Calculator tells you the maximum efficient speed for any displacement hull based on waterline length — so you stop wasting fuel pushing past physics.

Enter waterline length, beam, and displacement to instantly see theoretical hull speed in knots, mph, and km/h. The app calculates Froude number, speed/length ratio, displacement/length ratio, and whether your hull can realistically plane.

HULL SPEED CALCULATOR Enter waterline length and displacement to calculate theoretical hull speed. Shows speed/length ratio, Froude number, and hull speed in knots, mph, and km/h.

SPEED TABLE Reference table showing hull speeds for waterline lengths from 15 to 60 feet at speed/length ratios of 1.0 (cruising), 1.2 (fast cruise), 1.34 (hull speed), and 2.0 (semi-planing).

POWER GUIDE HP per ton requirements by hull type: displacement (under 40 HP/ton), semi-displacement (40-100), and planing (over 100). Includes example vessel types for each category.

SPEED CONVERTER Bidirectional speed unit conversion: knots to mph, km/h, and m/s. Enter any value and see all conversions instantly.

Built for naval architects, boat builders, and sailing enthusiasts. Works offline.