PROP SELECTION 3 BLADE VS 4 BLADE

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Kevin Craig
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PROP SELECTION 3 BLADE VS 4 BLADE

#1 Post by Kevin Craig » Wed Feb 21, 2018 9:15 am

I have A 22' Aluminum Pontoon with A 75 HP Mercury. Got it running great and looking into putting the best prop for the application although I know its not 100% unless you try different ones and come to your own conclusion. The one that came on it is A 3 blade , 15 pitch that measures 12.5 inches with very visible wear to it . In doing research I came up with 15 pitch also but in diameters from 13.25 and 13..75 . Figured I'd go middle of the road at 13.5 but had A thought of going to A 4 blade for more low end pushing power although I know high speed will suffer some. Since there are many of you out there much more knowledgeable on this than I what is y'all's input ? Thanks All !

Bamaman
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Re: PROP SELECTION 3 BLADE VS 4 BLADE

#2 Post by Bamaman » Wed Feb 21, 2018 7:20 pm

What revolutions per minute will your boat turn maximum? 15 pitch sounds like too much prop for a 75 hp. RPMs and speed tells the tail.

I am running a F150 Yamaha, and my Reliance 3 blade prop was essentially designed for my engine. It is perfect at 6000 rpms, 40 mph maximim :scared and a low 6% prop slippage.
'12 Bennington 24' SSLX Yamaha 150

Kevin Craig
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Re: PROP SELECTION 3 BLADE VS 4 BLADE

#3 Post by Kevin Craig » Thu Feb 22, 2018 3:24 am

I don't know what rpm's as I haven't had it in the water yet. Ill probably run the prop that came with it first and get ideas from there. Just trying to do A little ahead thinking.

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curtiscapk
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Re: PROP SELECTION 3 BLADE VS 4 BLADE

#4 Post by curtiscapk » Thu Feb 22, 2018 8:10 am

yep can't do anything without WOT RPM readings!
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Kevin Craig
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Re: PROP SELECTION 3 BLADE VS 4 BLADE

#5 Post by Kevin Craig » Thu Feb 22, 2018 11:53 am

Does anyone run A 4 blade or isn't that the way to go ?

ron nh
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Re: PROP SELECTION 3 BLADE VS 4 BLADE

#6 Post by ron nh » Thu Feb 22, 2018 4:11 pm

I use a 4 blade for tubing unless I'm to lazy to swap em, It doesn't lose grip at all. Actually I don't feel a difference with regular boating except can't get the RPM's high enough. I do lose a few MPH but it also handles better around the docks. I think its a 14.75 x 17. My 3 blade is 13.5 x 17. I don't think I know anyone who runs a 4 blade all the time with a pontoon but if it works good then it works good.
2015 Qwest LS 818XRE Tri-toon w/mercury 115.

ron nh
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Re: PROP SELECTION 3 BLADE VS 4 BLADE

#7 Post by ron nh » Thu Feb 22, 2018 4:15 pm

You can find bad reviews from every brand of boat ever made, Unless there are a bunch within a small period of time I don't really look at it like it's an issue.........oopps, I was wondering where this post went.
Last edited by ron nh on Sat Feb 24, 2018 8:12 am, edited 2 times in total.
2015 Qwest LS 818XRE Tri-toon w/mercury 115.

urbnsr
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Re: PROP SELECTION 3 BLADE VS 4 BLADE

#8 Post by urbnsr » Sat Feb 24, 2018 6:40 am

Using the info you posted, I would guess a 14" diameter, 13 pitch prop, 3 blade is a good fit to obtain correct WOT RPM. Again, just a guess.

I don't think a 4-blade prop is recommended for your application, but if you do, you might want to reduce the diameter closer to 13" while staying with the 13 pitch to compensate for the extra blade.

When replacing my last two outboard props, I have went from 3 blade to 4 blade. I can't give a direct comparison as I was also changing pitch in order to obtain recommended WOT RPM (the reason for the new props). I am happy with the selection so I have no motivation to see what a 3 blade prop of the same pitch would do.

YMMV

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willy13
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Re: PROP SELECTION 3 BLADE VS 4 BLADE

#9 Post by willy13 » Sat Feb 24, 2018 8:38 am

I have no real world experience between 3 and 4 blade.

If you go with a 3 blade, I can say that non-straked pontoons like more diameter vs. pitch and a prop with extra cupping. Something like a cupped 14" dia x 11" pitch prop might work well.

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