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## Crouch's Speed Calculator

Presenting a calculator for determining speed potential based on a hull's weight, its engine's horsepower, and a "hull factor" constant.

### Planing Hull Speed Calculator

This calculator is based on a formula developed by Naval Architect George Crouch who showed that a useful estimate of the speed of a moderate planing hull could be derived from the boat's weight, horsepower, and hull factor. The variables are related by

MPH = [ ( HP / LBS )^0.5 ] x C
where C = a constant ("hull factor") that depends on the hull form.

Crouch proposed that C would have a value for various hull types as follows

PLANING HULL SPEED CONSTANTS--MPH
C Hull Type
172 Average runabout, cruiser, passenger vessel
218 High-speed runabout, very light high-speed cruiser
240 Race boat types
253 Three-point hydroplanes, stepped hydroplanes
265 Racing power catamarans and sea sleds

The hull factor is a constant which is used to convert the necessary dimension. Most Boston Whaler hulls are in the range of 180 to 200,

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