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Yamaha 115 prop change

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BVColley

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Hello everyone! My 22’ Bennington seems slower than others on the lake around me. My goal is to get a faster cruising speed for long distances across the lake, I like to run around 4500 rpm’s. My prop is aluminum 13 1/4 x17. From all that I’ve read to increase speed, put more pitch on it without dropping the rpm’s too much. I purchased a stainless 13 x 19 prop expecting to drop 400 rpm’s with the two increase in pitch. For the test I had 3/4 tank of fuel and I was alone with only the prop as extras.
Going south with wind at back and trim as high as I could get it and at WOT which was 5900 rpm, I ran 25.5 mph, at 4500 I ran 19 mph, at 3000 I ran 11.5
After prop change with 1/4” less diameter and 2” more pitch I got!
Again going south at 5900 rpm (rpm did not drop) I ran 24 mph, at 4500 I ran 18.5, and at 3000 it was also 11.5 mph.
I could not run trim on the stainless as high, I had to lower it. Needless to say I was very disappointed! Was I expecting too much? My biggest surprise was all that I had read about not getting to much pitch and lowering the WOT to much, and I had no change at all. Aluminum prop is back on. Thoughts?
 
You didn’t say which model Bennington you have and the heavier models will naturally be slower. I have a 22RL express toon with a Yamaha 115 with a 13 1/4 x 15. My WOT is 28 when clean toons. Don’t think I am truly propped right but don’t care as I am a slow cruiser, never in a hurry usually cruise around 15mph
 
Link said:
You didn’t say which model Bennington you have and the heavier models will naturally be slower. I have a 22RL express toon with a Yamaha 115 with a 13 1/4 x 15. My WOT is 28 when clean toons. Don’t think I am truly propped right but don’t care as I am a slow cruiser, never in a hurry usually cruise around 15mph
Click to expand...
It’s a 2277 RSFI
 
I think you're possibly going about this wrong. Pontoons - especially 2 toon versus tritoon - tend to act more like a displacement hull and have a lot of drag. As a result props need to have a lot of blade area, or "traction" using tire terminology, than a standard v-hull boat. When you have too little diameter the prop spills a lot of water off the blades due to resistance and you get a term called "slip". Imagine skinny tires spinning out on a heavy SUV when the accelerator is floored.

By going up in pitch you expected to gain speed, but you also reduced diameter which actually makes your situation worse. You need MORE diameter first, then work on pitch.

Yamaha has recommendations for pontoons but some of them can be confusing. Sometimes they recommend a 14x13, other times 13.5x17. I think it depends on how heavy the boat is, how many toons, diameter of toon, if you have a wave shield etc. but if it were me I would go with a 14 diameter prop (12-14 pitch) and see if you get more grip and actually pickup speed and fuel efficiency. If you can keep the RPMs in that 5500-6000 range all the better, but if not it will provide a valuable data point. Adjust from there.

I know buying, trying and returning props is a PITA but often times trial and error is the only way to truly get dialed in, short of having another user with the exact setup. A lot of us also recommend folks read out to Ken at Propgods who is regarded as one of the best prop guys around who has years of knowledge and can give some recommendations. Once you optimize the power on your boat all the effort will be worth it for many years to come!
 
Hello and welcome. Clean pontoons? Dirty pontoons can REALLY slow a pontoon down. This is usually the performance culprits on an older boat.

Also, what hull? Bi-toon, Elipticals, partial tri- EPP, for full tritoon SPS or ESP hull? That will have a big impact. Finally, no matter what, an “R” series is going to be a heavier boat, so that would certainly impact it.

Resource for you: Look in our sub-forum: “Members Zone: Props and Power” and the stickied thread “List Your Specs Here”. A Yamaha 115hp is pretty common. Look for the boat model, length and hull that you have on yours PAIRED with the 115hp Yamaha. That will give you good prop and performance ideas.

Direct Link to Above: List Your Specs Here

That said, I think you have too much pitch for a 115. There are a lot of prop factors besides just pitch size. Diameter size, cup of prop, weight of spinning an aluminum v SS prop, etc…. At WOT, light load of fuel, people and gear you want to be 5500-6000 RPM’s with your motor. Seems like you got there at 5900. So your performance numbers seems off as I have driven 115’s tritoons and get into the high 20’s to low 30’s pretty easily. IF its a tritoon, I have to wonder if you either have really dirty pontoons slowing you down, or water in your pontoons…which again would really slow you down.

For comparison with pitch. I have a supercharged 200HP Mercury Verado Pro with a 16p SS Enertia Prop. That’s a 16p SS on a 200, and to be 100% dialed in these days I really should drop to a 15p Enertia.

On your boat I’d probably be trying a +/-13p if going SS. However, I would be going with an aluminum with your 115.

Personally, I lean SS if its a 150 HP or higher motor because the prop wont flex at WOT, whereas an aluminum one would. But for your 115HP, you should easily be able to dial it in if the pontoons are clean, no leaks, with an aluminum prop and no flexing.

That said, I am not on top of aluminum props and performance so hopefully others, or the link above, can guide you. Now if you answers some of the questions above that will really help people give you good advice.
 
Vikingstaff said:
Hello and welcome. Clean pontoons? Dirty pontoons can REALLY slow a pontoon down. This is usually the performance culprits on an older boat.

Also, what hull? Bi-toon, Elipticals, partial tri- EPP, for full tritoon SPS or ESP hull? That will have a big impact. Finally, no matter what, an “R” series is going to be a heavier boat, so that would certainly impact it.

Resource for you: Look in our sub-forum: “Members Zone: Props and Power” and the stickied thread “List Your Specs Here”. A Yamaha 115hp is pretty common. Look for the boat model, length and hull that you have on yours PAIRED with the 115hp Yamaha. That will give you good prop and performance ideas.

Direct Link to Above: List Your Specs Here

That said, I think you have too much pitch for a 115. There are a lot of prop factors besides just pitch size. Diameter size, cup of prop, weight of spinning an aluminum v SS prop, etc…. At WOT, light load of fuel, people and gear you want to be 5500-6000 RPM’s with your motor. Seems like you got there at 5900. So your performance numbers seems off as I have driven 115’s tritoons and get into the high 20’s to low 30’s pretty easily. IF its a tritoon, I have to wonder if you either have really dirty pontoons slowing you down, or water in your pontoons…which again would really slow you down.

For comparison with pitch. I have a supercharged 200HP Mercury Verado Pro with a 16p SS Enertia Prop. That’s a 16p SS on a 200, and to be 100% dialed in these days I really should drop to a 15p Enertia.

On your boat I’d probably be trying a +/-13p if going SS. However, I would be going with an aluminum with your 115.

Personally, I lean SS if its a 150 HP or higher motor because the prop wont flex at WOT, whereas an aluminum one would. But for your 115HP, you should easily be able to dial it in if the pontoons are clean, no leaks, with an aluminum prop and no flexing.

That said, I am not on top of aluminum props and performance so hopefully others, or the link above, can guide you. Now if you answers some of the questions above that will really help people give you good advice.
Click to expand...
Thank you! 2 pontoons, both clean. I will go to that link.
 
Potomacbassin’ said:
I think you're possibly going about this wrong. Pontoons - especially 2 toon versus tritoon - tend to act more like a displacement hull and have a lot of drag. As a result props need to have a lot of blade area, or "traction" using tire terminology, than a standard v-hull boat. When you have too little diameter the prop spills a lot of water off the blades due to resistance and you get a term called "slip". Imagine skinny tires spinning out on a heavy SUV when the accelerator is floored.

By going up in pitch you expected to gain speed, but you also reduced diameter which actually makes your situation worse. You need MORE diameter first, then work on pitch.

Yamaha has recommendations for pontoons but some of them can be confusing. Sometimes they recommend a 14x13, other times 13.5x17. I think it depends on how heavy the boat is, how many toons, diameter of toon, if you have a wave shield etc. but if it were me I would go with a 14 diameter prop (12-14 pitch) and see if you get more grip and actually pickup speed and fuel efficiency. If you can keep the RPMs in that 5500-6000 range all the better, but if not it will provide a valuable data point. Adjust from there.

I know buying, trying and returning props is a PITA but often times trial and error is the only way to truly get dialed in, short of having another user with the exact setup. A lot of us also recommend folks read out to Ken at Propgods who is regarded as one of the best prop guys around who has years of knowledge and can give some recommendations. Once you optimize the power on your boat all the effort will be worth it for many years to come!
Click to expand...
Thank you!
 
My last boat was a two toon 22 foot G series with a Yamaha 115. Wish I could remember the prop size but I don't. Top speed under ideal conditions was 26 MPH. You wrote in the specs thread your top speed is 25.5. Not sure you're going to gain much with a different prop.
 
sunedog said:
My last boat was a two toon 22 foot G series with a Yamaha 115. Wish I could remember the prop size but I don't. Top speed under ideal conditions was 26 MPH. You wrote in the specs thread your top speed is 25.5. Not sure you're going to gain much with a different prop.
Click to expand...
Yeah, probably not! I was really looking for a faster “cruising” speed, around the 4000-4500 rpm area, but after reading the comments and going to the link that was provided which tells the performance of different set ups, I’m satisfied with what I’ve got. Thanks for your reply
 
I had leaned into an assumption that you had a tritoon. With a bi-toon, I think you are about where you are going to get. Not much more as that 115hp is really plowing through the water.

If it were a tritoon, then I’d expect another 5-8 mph out her pretty easily.
 
I have a 2019 22’ GSR with sea legs (ultra legs), two toons, no lifting strakes or splash guards, and average top speed 22-23mph. It does plow through the water versus get up on top. I can’t even adjust the motor trim.
 
BVColley said:
Hello everyone! My 22’ Bennington seems slower than others on the lake around me. My goal is to get a faster cruising speed for long distances across the lake, I like to run around 4500 rpm’s. My prop is aluminum 13 1/4 x17. From all that I’ve read to increase speed, put more pitch on it without dropping the rpm’s too much. I purchased a stainless 13 x 19 prop expecting to drop 400 rpm’s with the two increase in pitch. For the test I had 3/4 tank of fuel and I was alone with only the prop as extras.
Going south with wind at back and trim as high as I could get it and at WOT which was 5900 rpm, I ran 25.5 mph, at 4500 I ran 19 mph, at 3000 I ran 11.5
After prop change with 1/4” less diameter and 2” more pitch I got!
Again going south at 5900 rpm (rpm did not drop) I ran 24 mph, at 4500 I ran 18.5, and at 3000 it was also 11.5 mph.
I could not run trim on the stainless as high, I had to lower it. Needless to say I was very disappointed! Was I expecting too much? My biggest surprise was all that I had read about not getting to much pitch and lowering the WOT to much, and I had no change at all. Aluminum prop is back on. Thoughts?
Click to expand...
For comparison…my 2275GCW has a 115 HO and runs 28 mph with 2 people and half tank of gas. Using 13 pitch SS and my rpm’s on spot on. Full load or dirty toons will slow you up some. Sounds like yours is pretty much rigged properly.⚓️⚓️
 
Angela & Michael said:
For comparison…my 2275GCW has a 115 HO and runs 28 mph with 2 people and half tank of gas. Using 13 pitch SS and my rpm’s on spot on. Full load or dirty toons will slow you up some. Sounds like yours is pretty much rigged properly.⚓️⚓️
Click to expand...
What is your diameter?
 
My prop is 13.75 x 13 Solas Saturn stainless steel.
 
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