View Full Version : Prop questions....

08-06-2003, 11:04 AM
A random question, and some of you may think I'm mad but.......

I recently aquired a 97 Moomba Boomerang through a friend of mine. I have skied a few hours behind it, and more than enjoy it. After much though and deliberation, I was thinking about changing the prop to something more aggressive.

I believe the original prop is a 13-13 3blade. Engine is the 351 (260hp) carb, top speed on the boat (unloaded) is about 45 MPH at about 4400 RPM.

What I'm wondering about is changing to a 13-16 or maybe something slightly more. Main reason is speed vs. horsepower vs. economy. I feel that the boat is aggresivley overpowered for the amount of skiiing and knee boarding that me and my kids do. In all honesty, I feel like I'm being held back.

I would like it to go faster (yes, I do like to ski fast), my kids are very lean and light, and I'm a showoff at heart :) I do not think that changing the prop would effect our holeshots too much and it may change the wake slightly.

Many people compliment the boat on the lake where we run regularly, and many of my friends have commented it should be faster. Should it be? Am I just crazy? Suggestions are welcome about prop configurations.

The J.Jones
08-06-2003, 03:21 PM
I've always been of the believe that the 45 mph top speed you listed is about "it" for inboard boats. I don't think I've ever been in (or even seen one) go 50+. Sounds like to me the people who are claiming your boat should be faster, need to ride with you from a dead stop to about 35....then re-evaluate!

In my opinion, I'd rather have the low-end grunt and sacrifice a little top speed, but to each their own. Good luck with whatever you decide to do.

Another option is that you could go bigger (to increase top end) but maybe go to a 4-blade which is said to increase low end....might be the perfect compromise.


08-06-2003, 05:05 PM
You need to check your engine manual and find out what the WOT (wide open throttle) range is for your engine and ensure that you stay within it regardless of the prop you use.

If you are over-propped your max RPM will be below the WOT range and you will be placing tremendous load on your engine which can cause preignition and detonation, all of which can be fatal to your engine.

If you are under-propped, your max RPM will be above your WOT range which can also lead to catastrophic damage.

Definitely get the assistance of an experienced dealer with this if you have any plans for keeping your engine healthy.