3 blade too 4 blade same pitch

vtindy · May 10, 2011

I have a 3.0 in 2002 18.5ft monterey edge I'm running a 14.5x19 prop 3 blade pulling tubers and skiers it's and it's in the right rpm range 4400-4800 and i,m happy with the prop. My question is i ding the prop and need too rebuild or replace it. If i replace it with a solas 14x19 4 blade prop both props being alumminum will i gain any thing power wise? Just wondering top speed with 3 blade is 38 gps. if i loose a little top in it's ok. thanks in advance.

Robbabob · May 10, 2011

Re: 3 blade too 4 blade same pitch

Hi and welcome to iBoats!

Nothing is going to change power wise. You have the same engine.

As for performance... yes, you will get better hole shot, better handling at slower speeds, and your top end will reduce a little. The .5" reduction in diameter should show little change... roughly a 50 RPM increase.

Let someone with a little more experience chime in on this next part.... You may possibly want an 18P 4-blade to keep the top end RPM in line with the engine spec.

Good luck!

fossill · May 10, 2011

Re: 3 blade too 4 blade same pitch

Probably need to go to an 18 pitch. Hard to say without knowing your exact wot rpm.

Mac525 · May 10, 2011

Re: 3 blade too 4 blade same pitch

I agree with Rob but what is your wot rpm at the high side or low, two of the biggest impovements found with four blade hole shot and low planing speed, most people find better mpg at cruise as a bonus

sschefer · May 10, 2011

Re: 3 blade too 4 blade same pitch

Rule of thumb when going from 3 to 4 is to drop an inch on both diameter and pitch. Typically you'll lift the bow better and have a better hole shot but the top end won't suffer more than 1 or 2 mph. That's the way mine worked out.

WINTERSUX · May 15, 2011

Re: 3 blade too 4 blade same pitch

got to ask, what does WOT mean?

Rudy Brown · May 15, 2011

Re: 3 blade too 4 blade same pitch

WOT= wide open throttle

rkcarguy · May 17, 2011

Re: 3 blade too 4 blade same pitch

Solas has a 14.5x17 4-blade I would try, my holeshot and cruise speed improved, wide open suffered a little but who needs it?
If you stay with the same dia prop I would go down 2" in pitch with a 3.0L. The 4-blade has alot of extra bite that will bring your wot rpm down considerably.

Mac525 · May 20, 2011

Re: 3 blade too 4 blade same pitch

rk wot throttle rpm is an indication of how much load is on your motor and being at the very bottom of the spec or bellow can bring premature wear and failure of your engine and or leg due to overloading even if you would never run at wot its really the only way to tell where your at with the spec plus over proping a boat will kill its mpg at cruise speeds

Robbabob · May 20, 2011

Re: 3 blade too 4 blade same pitch

I only passed on finishing this thread as I don't have first hand knowledge about the Solas, the OP mentioned having one to try (or something to that effect).

Pssst, Mac -- I think you read rk's comment wrong.
"my holeshot and cruise speed improved, wide open suffered a little but who needs it?" His comment refers to top speed suffers.
"If you stay with the same dia prop I would go down 2" in pitch with a 3.0L. The 4-blade has alot of extra bite that will bring your wot rpm down considerably." He knows the rpm will drop, so he recommends keeping same diameter and pitching down 2" to make up for the loss.

Anyway, just wanting to help curb a misunderstanding and having someone ruffle their feathers

Enjoy this Friday!

Mac525 · May 20, 2011

Re: 3 blade too 4 blade same pitch

You are right rob I did asume he was talking about rpm and Im sorry for any confusion rk, there are alot of guys running an over propped setup and are over working there engines

3 blade too 4 blade same pitch

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