[PSUBS-MAILIST] Horsepower vs. thrust in pounds

["Michael B. Holt" <mholt@richmond.edu>]

This has always irritated me; we go off to buy an electric trolling
motor of a certain horsepower, only to find that some technological
terrorist has rated them in pounds of thrust.

Wandering through some old books, I think I found a way to beat hte
problem.  "The Marine Engineer" of July 6, 1906, has an article on
"Propellors."  Int those days, a propellor was anything that propelled a
boat or a ship, so the article includes interesting stuff about paddles
wheels and pumps.  

The formula on page 575 follows as best I can render it:

Pounds thrust = (horsepower * 33,000)/(pitch * rpm)


I should work up a table.  What's tjhe rpm and pitch of some trolling
motors?


Mike Holt