|PMY 2002 Performance Wrap-Up|
Transport Factor—How You Get It
By George L. Petrie
Factor = Weight x (Speed x 1.689) / (Power x 550)
For each yacht, we took the builder’s figure for dry weight in pounds,
to which we added the weights of fuel, water, persons, and gear onboard
during our test, as reported in each PMY boat test article.
Speed. Top speed in knots, as measured on test day, based on a two-way average measured with a Stalker radar gun. Multiply by 1.689 to convert from knots to feet-per-second, the units required by the formula.
Power. Maximum rated horsepower of the engines installed on the test boat, as per the engine manufacturer’s specifications. Multiply by 550 to convert from hp to foot-pounds-per-second, the units required by the formula.
Speed-Length Ratio. Top speed, in knots, divided by the square root of the yacht’s at-rest waterline length in feet. —G.L.P.
This article originally appeared in the January 2003 issue of Power & Motoryacht magazine.