Re: Crouch's Calculator

Optimizing the performance of Boston Whaler boats
Posts: 9637
Joined: Fri Oct 09, 2015 12:25 pm
Location: Michigan, Lower Peninsula

Re: Crouch's Calculator

Postby jimh » Sun Oct 23, 2016 8:36 am

Crouch's method came to my attention in a book, PROPELLER HANDBOOK, written by naval architect Dave Geer. The original speed predictions and hull constants were for boat speeds in nautical-miles-per-hour, but I preferred to use statute miles per hour, and emended the formulas to give the predictions in that speed unit. I created an on-line interactive calculator that was quite unusual and was the first known implementation of Crouch's method in an on-line calculator.

Although another on-line calculator attributes this analysis to Mercury Marine, the method is identical to Crouch's analysis. The basis for Crouch's Calculator was the observation that boat speed is proportional to the power-to-weight ratio to the 0.5 exponent times a constant that was scaled for the type of moderate v-hull planing boat being analyzed. For a typical Boston Whaler hull the hull factor of 180 can be used to get a reasonable estimate of hull speed potential in MPH.

UPDATE: The original Crouch's Calculator that first introduced using a calculator to predict boat speed using the Crouch Speed Prediction Method has nowbeen restored. See