Where will my RPMs be with this prop?????

[natedog337]

I own a 2011 26 ft pontoon and was looking to upgrade my prop.
I'm pushing a 13 pitch 3 blade now which results in 22 MPH at 6200 WOT.

Thinking of switching to 4 blade 15 pitch but wondering where my rpms will be with the change in blade and pitch... thxs

 

[steelespike]

Re: Where will my RPMs be with this prop?????

Your being unfair we need to know the year,hp and brand of motor to be accurate in our "guess.
In the extreme it could reduce your rpm up to about 500.Also if you read the stickies at the top of the page and give us all the info we may be able to make other suggestions.

 

[natedog337]

Re: Where will my RPMs be with this prop?????

The boat is a sweetwater 240 with a yamaha F115...The recommended wot range is 5000-6000. was hoping to switch from 3 blade 13 pitch to 4 blade 15 pitch and pick up some holeshot and possible top speed without straining my motor. But if my WOT stays around 5700 im sure thatll be fine...

 

[steelespike]

Re: Where will my RPMs be with this prop?????

The boat is a sweetwater 240 with a yamaha F115...The recommended wot range is 5000-6000. was hoping to switch from 3 blade 13 pitch to 4 blade 15 pitch and pick up some holeshot and possible top speed without straining my motor. But if my WOT stays around 5700 im sure thatll be fine...

Usually they try to prop the 4 strokes close to their max rated rpm.Typically when going to a 4 blade they suggest dropping one inch pitch to maintain rpm So if you increase pitch You'll probably lose about 500 rpm putting you at the arbitrary 5700 you suggested.Keep in mind that these figures aren't carved in stone.
Increasing pontoon speed is pretty hard so your final results may be dissapointing .
The 4 blade should have better slip numbers and the pitch increase may net a little speed.
4 blades shine in low to midrange performance and may improve response at the dock.
They also resist venting so you may be able to raise the motor on the transom reducing drag a little.
When selecting a prop I don't usually mention diameter but a 4 blade with a larger diameter may perform better on a pontoon.

 

[mpsyamaha]

Re: Where will my RPMs be with this prop?????

those f115s like to be revved up, and they are really not a great motor for heavy boats... just not much torque there for holeshot and midrange. i have seen these motors perform nice on a smaller lighter hull, but they seem weak on a heavy boat like a catamaran hull or pontoon boat. you may gain slight top speed by increasing pitch, but id almost be more incline to look for a 13p 4 blade prop.

 

[jlvardon]

Re: Where will my RPMs be with this prop?????

I have 25' Harris pontoon with a Mercury 115 4 stroke. With a 13.75" 15P prop I can get 27-28MPH at 5700 - 5900 ish RPM with two people, and 22ish MPH at 5200 RPM with the family loaded on it like it normally is.


The WOT of the motor is 5800-6400 RPM and I am actually thinking of going with a 14" 14P prop to help get some RPM.