Propeller choice OMC Cobra 30 on 17 foot bow rider

"I am trying to improve perfor

"I am trying to improve performance on my boat, and believe a prop upgrade is in order.
Here is current setup:
1988 OMC Cobra, 3.0L
17 foot Renken SS1700, 1988
Running a 13x19 prop now.
WOT rating for the engine is around 4500 per manual.
The boat runs right at 4500 at WOT, but only at about 35-36 MPH, with trim full down.
If I trim up a bit I can approach 40MPH, and could possibly get higher, but the RPM gets over the max rating. So, I haven't pushed it as I don't need a blown motor. Not good I don't think.
I also have difficulty getting on plane with 3 or 4 people on board and the top speed also falls quite a bit. If it is just 1 or 2 people this is less of a problem.
The boat has a clean bottom and low hours, it's in perfect mechanical shape.

I am of the opinion that increasing pitch to let's say 21 would improve top end. There would be a corresponding decrease in RPM, but I also know that if I trim up to where I get better speed with the current prop, I would have the motor in the correct range. However I am not sure this would help my holeshot/ getting on plane problem. It may be I need a different prop for each operating condition, correct?
My marina does demo props, and they suggested going to a 17 pitch for more speed, but I question this, as it would seem to over-rev the motor, based upon what I have read. Increased diameter might also be a help I suppose.

Any of you that have experience and can comment on this.. please fire away.

Thanks
Craig"

"I think you've pretty muc

"I think you've pretty much got it nailed down. Welcome to boating and COMPROMISE! As a rule of thumb an inch of pitch will change RPM's close to 200 so if you go for a 21, your RPM's will drop down to around 4100 but by trimming it up you'll probably end back up around 4400-4500. You will probably see a couple more MPH out of that prop however and you've already mentioned this it will have a bit of a negative impact on your holeshot. Another thought to help your holeshot is product out there called "Smart Tabs" they help you your boat take by raising the stern which gets the bow down quicker. Those along with a 21 prop might give you what your looking for. Definitely stay away from that 17 pitch, it will help the hole shot but will put you way over the RPM range."

"Just an update Bob... I insta

"Just an update Bob... I installed the 14x21 today, and the change is dramatic.
Got 48 MPH out of it at WOT,in choppy water.
Going to try it again tonight on calm water.
Getting on plane was excellent but haven't tried out a run with passegers yet.
Side note was that as I left the dock for the first run with the new prop, I noticed my temperature running very high. Shut it down, let it sit a while, checked the intakes for weeds, and it still overheated again.
So, a quick impeller change and back in the water, all is well again.

Thanks for the feedback.

Craig"