cant really be done with out a prop gauge? why are u trying to measure no #'s on prop? it has to do with how far it would travel in one revolution in inches
Alumi, I decided enough people come on here having no idea what diameter and pitch prop they have so I wrote a little paper on how to find what pitch prop you have.
Here is the link http://forums.iboats.com/showthread.php?t=332091