What does the size on a prop mean IE. 15.25 x 15 p. I think the 15 p means the pitch, just don't know the first part. Looking to get a spare prop and have access to a 13.75 x 21p prop. Will this fit my boat, 305 chevy motor, mercruiser outdrive, 1977 mirro, cruiser boat, kind of heavy, max rpm...
