Re: Determineing prop slip
You use a prop calculator like the one below. There are lots of them on-line if you search for "prop calculator". It is impossible to have zero slip or negative slip so keep that in mind. What you need however, whether calculating manually or with a calculator is the lower unit gear ratio, the prop pitch you are testing, engine rpm at wide open throttle with an average load, and speed. Engine rpm is not what the manufacturer recommends, it is what you actually observe on the tach. Once you determine slip, what do you intend to do? Knowing what the slip is means nothing unless you know whether it is good, bad, average and then how to improve it if necessary.
http://www.rbbi.com/folders/prop/propcalc.htm
