Which Prop To use?

[ScreaminToon]

I have a 23ft ercoa pontoon.. i put a 175 evinrude on it and i have a 15X17 prop at WOT im pushing 4500 Im told this motor should run to 6000 rpm. with the 17 pitch it comes out of the hole like a jet boat but doesnt run up that high

 

[junior1113]

Re: Which Prop To use?

have a 93 200 evinrude and run in the 5600-5900 range you would need a 15 most likely a 13 5000 and up to 6000 is optimal range

 

[Dhadley]

Re: Which Prop To use?

There are more than one 175s. It would help to know what year yours is. As for propellers, there are pontoon specific props. To get an accurate assement of what you have vs what you might need we need to know what prop, brand and model, you are running now.

Normally if the boat gets out of the hole well the top rpm will be more than 4500. We should verify the top rpm before going further. If it is indeed only 4500 we may need to verify the accuracy of the tach. If it's OK then we might look at the motor to make sure everything is OK there.

 

[ScreaminToon]

Re: Which Prop To use?

Ya I have a 1994 Evinrude 175hp V6 and I think the Tach is correct i already checked that and it told me to set it to 6p which it is. and i mean i have a pretty good ear for that kind of stuff and it sound to be correct i know for a fact its no where near 6000rpm

 

[ScreaminToon]

Re: Which Prop To use?

so does anyone have an idea of which prop to use.... correct me if im wrong but doesnt smaller pitch equal more low end and less top end i know it should raise the rpms if you pitch down but will raising the rpm compensate for the less pitch on top end

 

[solar7647]

Re: Which Prop To use?

If the engine isnt running high enough rpm at WOT you need to decrease the pitch of the prop 1 inch decrease should make about 300-400rpm diferance so it sounds like you need to bring it down 2 maybe 3 inches. Good Luck

 

[solar7647]

Re: Which Prop To use?

The more you decrease the pitch the more top end you will loose. The more you increase the better top end is but its get's sluggish out of the hole.

 

[hwsiii]

Re: Which Prop To use?

Screamin, I show 4 different Evinrude 175's built that year, two of them them have recommended WOT ranges of 4,500 to 5,500 RPM and two of them have a WOT of 4,750 to 5,750 and all of them have a gear ratio of 1.86 to 1, verify this information please. I do not know if you have the recommended prop for a pontoon boat, but what I show at 4,500 RPM with the prop you have now should be right at 35 MPH with a 10% Slip factor. To be around 5,000 RPM you would need to change to a 15" prop, but to get closer to recommended WOT I would recommend a 13" prop in the same model prop you have now. It may not be the best prop for your boat, but I can mathematically figure the RPM that you will be turning with this prop. With this 13" prop you will be turning almost 5,600 RPM, which is right between the 5,500 and the 5,750 and will be running at the top of the RPM range. Here are the numbers for a 13" prop of the same model you have now. You should be running right at the same speed you have now at these RPM, as the prop will be turning more RPM to make up the difference in the speed. The reason I can't tell you what other props will do is because there might be a very dramatic change in the geometry from one prop to another.

Dhadley can probably help you pick the right prop for a toon, because I have no experience with them.

H