I'm interested in this too. I've searched the web and can't come up with much info. I have a 1989 Yamaha 90 HP on a 25' pontoon. I've probably got the original prop on it with some dings and I'd like to replace it with an aluminum prop - possibly a SS one (depends on if I can find a deal or not). I pull more heavy loads (of people and beer) than have a need for speed. Right now she cruises at 23 mph with me, minimal gear and a full tank of gas. With a load of people and gear, I'm probably around 18 mph. Any suggestions would be appreciated.