Prop selection

[dannyj315]

I have a bennington 21slx with the f115. The Prop that is on it now is an aluminum 13.5 by 15p. I have had the boat up to 49 which runs at 6400rpm which is way to high. im looking to change props to stainless and looking for higher top speed. I know they are not meant for speed but im sure people have tested different props. the boats about 3500 lbs including passengers. im thinking of going to a 19 pitch with 13.25 diameter? anyone have any suggestions or have changed their yahmaha prop on their pontoon

[pstephens46]

I have a bennington 21slx with the f115. The Prop that is on it now is an aluminum 13.5 by 15p. I have had the boat up to 49 which runs at 6400rpm which is way to high. im looking to change props to stainless and looking for higher top speed. I know they are not meant for speed but im sure people have tested different props. the boats about 3500 lbs including passengers. im thinking of going to a 19 pitch with 13.25 diameter? anyone have any suggestions or have changed their yahmaha prop on their pontoon

You have a pontoon boat that weighs over 3000 lbs that can hit 49mph with an F115. Not sure if there is any more you can add with a prop change. Who knows.

[rodbolt17]

I would have my tach checked.
most all the F115 I have dealt with the rev limiter gets it at about 6200.

[99yam40]

I would have never though a 22' pontoon could go 49 with a single F115.
might need to check you speedometer too.
when you switch to SS the props usually have more cup to them and will be like going up in pitch.

might see if you can find some info on here Outboard Performance, Performance Bulletins | Yamaha Outboards


as a matter of fact there was one listed, but it only got to 35
http://yamahaoutboards.com/sites/def...-10-28_PNT.pdf

and the one with a F150 only hit 41

[panasonic]

I have a bennington 21slx with the f115. The Prop that is on it now is an aluminum 13.5 by 15p. I have had the boat up to 49 which runs at 6400rpm which is way to high. im looking to change props to stainless and looking for higher top speed. I know they are not meant for speed but im sure people have tested different props. the boats about 3500 lbs including passengers. im thinking of going to a 19 pitch with 13.25 diameter? anyone have any suggestions or have changed their yahmaha prop on their pontoon

You using a GPS to get that speed reading??

[Jason2tpa]

I feel the need, the need for speed! Top Gun moment, couldn't resist.

As you increase pitch you'll decrease rpms, which in your case is a good thing since the boat is over propped. Be that as it may, your prop pitch selection should be guided by the engines spec rpm range @ WOT, not speed.

When fine tuning prop pitch, or engine height, or load, etc, you might see an increase or decrease in top end speed at WOT...but were talking about small increments mph. So if what you're looking for is more speed there is only 2 options....strip the pontoon of all non essentials, including passengers, OR get a bigger engine. The latter option tends to work out better.

Good luck.

[dannyj315]

sorry I miss typed. The mph was 39 mph not 49. it that was the case I would be more then happy with the speed. ill told the mech at the marina about the rpms that why I asked about the prop. those stats that came from the performance bulletins for that size boat have a wider in diameter prop along with a smaller pitch I believe. That's why I asked. As far as the speed. I have have two separate gps say 39.1mph minus 1+- due to water conditions. just looking for a few more mph out of it.