Yes this is a skiing forum but I'd like some advice on a new prop.
I've got a 4 stroke Yamaha 90 o/b pushing a 500lb mahogany hull. Total weight with motor 850 to 900lb. 3% deadrise (nearly flat bottom hull). My current prop is a 14.25 diameter 19 pitch 3 blade prop.
I'd like to make sure I can pull anyone in the world out of the water so I guess I should go to a stainless 4 blade. My question is, how do I go to a 4 blade while keeping all my top speed? (45mph).
Currently I'm able to pull a friend who is 6ft 3 and 230lb on a big ski, but I've got another bud who is 210 who insists he needs at least a 140hp motor to pull him out. I think he's got a pretty short skinny ski. I just want to get a little more pulling power (out of the hole) while maintaining my current top speed.
I'm sorry, but I Have no expertise in this area. Hopefully someone else on this forum will have some insight for you. Have you thought about contacting OJ or Acme Props directly?
From what I've read on another forum, Eric at OJ props may be able to answer your questions. I think they may only deal in inboard boat props, but if he can't answer your question he may know who can.
Asking for a better hole shot without losing top end may be asking too much though. It's rare for a tournament ski boat to have a top end much faster than 45 mph, but they will yank you out of the water real fast.
I am no expert but if you can pull the big guy out on your current prop then a 17 pitch 3 blade prop would likely do the job for your other friend. It is unlikely that you will find anything that will give you more hole shot and maintain your top speed. I am not sure how the 4 blade stainless would perform on a engine with only 90 hp. If you are looking for hole shot the lower pitch is really the only way of improving significantly with a small engine. You will sacrifice top end.
I would try the 3 blade aluminum and save a pile of money over a stainless 4-blade. Make sure you watch your engine revs as the lower the pitch the higher the engine will revolve at ski speed.
Otherwise tell your other friend to buy a snorkel and hold on for the ride!