Im looking into a new prop myself. I've been doing some reading here on iboats about props.I was pretty unaaware of all the variable ie, pith diameter,cupping, etc. I would thing that the weight and length of a boat would have some affect on which prop you choose. Boat manufactures test run thier boats and select proper diametet and pitch. If you repower with a different outboard make, Hp. Would you have to retest bebore making a final selction on a prop?