Only getting 4700 RPM max

M Butler

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9BC28BC8-4117-400E-86EB-214063732A0E.jpeg D4A2B5AA-68F9-4D41-8163-89CE2D15494C.jpeg I switched out props yesterday but the storms kept me off of the water.
I went from a PowerTech SS 13x14 to a Michigan aluminum 13 5/8x13. Hopefully I’ll get a chance this week to try this one out and I’ll update.
 

the-little-B

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I hope the Michigan works out for you but to me it looks an awful lot like the Yamaha K prop that didn't work. Only one way to find out though!
 

M Butler

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Well... different prop and same results. Time to take it in and let the pros figure it out!
 

Michiman

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Well... different prop and same results. Time to take it in and let the pros figure it out!
Bummer but hopefully they get to the bottom of it quickly!
 

cwag911

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!3p is still too big.
 

the-little-B

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After going through and testing several props , the best all around performer I've found is the rubex 13.8x13.

With just me on the boat it runs right at 6000 rpm and has no cavitated even in a hard turn. And it's at 27+ mph.

I had the Solas 13.5x15 repitched to a 13. It ran low at 4900-5000 rpm and now it's 5400 maybe a touch more but it ran 27.5 mph on a very windy and choppy day. I think that will end up being my fastest prop but really no good when passengers are on board.

It's frustrating for sure! I hope someone can help get you squared away soon!
 

M Butler

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Long overdue update! Finally got the boat in to the shop and was told that the air filter was collapsing, keeping it from reaching its potential. They put a new one in and now I’m getting the full 6000 rpm and running 26mph by myself. I’ll play with the props some and see which one works best for different scenarios. Thanks for all of the help and suggestions.
 

marfie

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I went through the pains of finding a prop to work on mine this summer too. I think I can help you out here. Mine is also a 20' , 90hp Yamaha , and 25" tubes.

Your rpm and speed sounds like a lot of prop slip to me. One prop I tried behaved like yours and it was because of it being the wrong style of prop. It was a pointy bladed prop , if you will , vs a more paddle shaped rounded blade needed on a pontoon.

Here is a short summary of props I tried...

Boat came with a 13.5x15 solas. Too much prop. Top was 4900-5000 rpm.

Tried a Yamaha "K" series 13 5/8x13. This was the pointy bladed prop and constantly cavitated and had no "traction" no matter what I did. Speed was in the low 20's.

Next was a Yamaha 13.5x14 Talon prop. Top was 4800-4900 but performed well. This is an aggressive prop and has cupped blades i believe and is too much for the 90. Had it repitched to a 12 pitch and now it's running 5500 +or- a few and does 26.5 mph.

Then I tried a solas 13.8x13 and am running 27-28mph depending on conditions and right at 6000 rpm.

I also raised my motor up one hole and can trim up to 3/4 on the trim guage with the 2 good props before it blows out and don't have any cavitation on hard turns either.

So there are a few numbers that I think will get you headed In the right direction.
 

Bamaman

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Ask your dealer to meet you at the lake with 4-5 different props. It's his responsibility to get 100% performance out of your boat. The speedometer, the tachometer and prop ventilation speak to the proper prop and engine height. Stainless props are too expensive to experiment with.

My dealer mounts all his Bennies one hole up--3/4 inch off having the engine sitting on the transom. My F150 is setup perfectly with the 15 pitch Reliance prop.
 

Mr B

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After going through and testing several props , the best all around performer I've found is the rubex 13.8x13.

With just me on the boat it runs right at 6000 rpm and has no cavitated even in a hard turn. And it's at 27+ mph.

I had the Solas 13.5x15 repitched to a 13. It ran low at 4900-5000 rpm and now it's 5400 maybe a touch more but it ran 27.5 mph on a very windy and choppy day. I think that will end up being my fastest prop but really no good when passengers are on board.

It's frustrating for sure! I hope someone can help get you squared away soon!
I am a new owner to Bennington, but have been around boats most of my life. I have a 2019 Bennington SX20 with a 90hp Yahama. At first I had a Yamaha K prop (dealer installed). Motor is mounted all the way down. Prop would slip out at about 5500 and also in turns. Dealer gave me a Yamaha Talon 13.5X14. This prop is cupped. Prop stays hooked up always, even in tight turns. But, I only could get 5200 rpm at 28.5 mph gps. Just me in the boat, calm conditions. I want good performance when pulling kids on tube. The 14 pitch prop just didn't give me enough power to pull the tube the way I want to give a good ride. I tried Turning Point Hustler 14x11 and 14X13. Didn't like either of these as the do not have SDS (shift dampener system) and are very loud clunk when shifting and vibrate at slow speed. I settled on a Yamaha Talon 13.5X12. Prop grips very well, and holds solid in tight turns with tube. I get WOT 5900 at 28 mph gps with just me in boat.

My question for all is, have you experienced the splash of water coming off the toons to the inside and slamming up against the bottom of the boat. This creates vibration and slows the boat. Happens in clam water and choppy water. I do have the splash shields installed, which made it better, but it still slows the boat. Thanks for any input.
 

Vikingstaff

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I am a new owner to Bennington, but have been around boats most of my life. I have a 2019 Bennington SX20 with a 90hp Yahama. At first I had a Yamaha K prop (dealer installed). Motor is mounted all the way down. Prop would slip out at about 5500 and also in turns. Dealer gave me a Yamaha Talon 13.5X14. This prop is cupped. Prop stays hooked up always, even in tight turns. But, I only could get 5200 rpm at 28.5 mph gps. Just me in the boat, calm conditions. I want good performance when pulling kids on tube. The 14 pitch prop just didn't give me enough power to pull the tube the way I want to give a good ride. I tried Turning Point Hustler 14x11 and 14X13. Didn't like either of these as the do not have SDS (shift dampener system) and are very loud clunk when shifting and vibrate at slow speed. I settled on a Yamaha Talon 13.5X12. Prop grips very well, and holds solid in tight turns with tube. I get WOT 5900 at 28 mph gps with just me in boat.

My question for all is, have you experienced the splash of water coming off the toons to the inside and slamming up against the bottom of the boat. This creates vibration and slows the boat. Happens in clam water and choppy water. I do have the splash shields installed, which made it better, but it still slows the boat. Thanks for any input.

What kind of hull do you have: traditional 2 pontoons, EEP, SPS...? Kind of curious.

My instincts are that you have a dual toon, and probably to be expected as it cannot get up on plane and buoyant like a tritoon. That said, there is always going to be some level of water hitting up and under any pontoon. Underskinning is a major help, and then in regards to getting on plane and moving on the water, a tritoon with a higher HP motor.
 
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