WTF. I own a 1996 26' Bayliner Cierra with a 5.7L Mercruiser and Alpha I outdrive. I damaged my prop and bought a Mercury replacement with the exact same diameter and pitch (16"x16 pitch). On my test drive, the prop would begin to cavitate at various acceleration rates. Most noticeable was when I jammed the throttle wide open to quickly get on plane. The boat RPMs would start increase at a normal rate, then accelerate rapidly. The boat would then slow its acceleration as the RPMs increased. I can get the boat on plane with slow throtlle manipulation while listening for the sounds of cavitation and backing off on power. My old prop did not cause the boat to cavitate, or if it did, it was never noticable by the RPM gauge or make a distinct sound. The new prop is the "flow through" design that does not have a solid splined hub like the original prop. Can anyone tell why a direct size replacement prop would cause this problem. I did not know my exact WOT PRMs before I bought the new prop, but now they are at 4200. I belive my boat should be at 4600-4700 WOT. Can some tell me the size prop I need. My research says I should go to an 18 pitch. What about three blades vrs. four blades. I want to stick with AL. Any suggestions on which manufacturer? Can I run the new prop for the rest of this season and not cause engine damage? Sorry for the long thread, but this is extemely fustrating. I just spent two boat bucks for nothing.