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JohnWestlund

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Hello, Everyone I need some advise from the pros! I have a 2015 22GS Pontoon with Sea Legs. I wanted to update to a stainless prop. The Original prop was a 13.50 x12-K . I could never get more than 22 mph- I tried the Solas 13.75 x15 SS . My RPM dropped as expected but it had cavitation really bad at 3/4 throttle . The sea legs weigh 300-350 pounds ( Both props were 3 Blade) what do you recommend I try?
 
Hey John - a few details are needed in order for the community to help out such as engine model/HP and if you have two or three logs. Also if you can recall max RPM on your two props that would help narrow down the selections as well.

Thanks!
 
Thanks for getting back to me so quickly. I have a F115 Yamaha . Just a two Log toon. My RPMS went from the 13.50 x12 prop at 6400 RPMs Down to 5200 RPMs on the 15 pitch. That's where it starts the Cavitation .
 
There seem to be a lot of threads for 115hp motors that you can search through - I would start there. Use other people's time, money, failures and successes to your advantage. You may not find a perfectly matched situation but can at least give you a good starting point.

That being said, with only two toons your boat will be plowing a lot of water i.e. not really getting up on a good, high plane like with a tritoon. Add in the additional weight of the sea legs, and my non-expert advice is to seek out a prop that has more blade surface area - you can either try a 4-blade prop or a larger diameter 3-blade. By doing so this allows the prop to overcome the drag and weight of your boat and turn as much of that thrust into forward motion, instead of wasted and spilling off the blades.

You may read or hear the term "slip" which is basically a % of lost theoretical forward motion for a given pitch. So if your prop is a 13p, it should move forward 13 inches per revolution in a perfect, theoretical sense. Your actual observed forward motion (lets say 12 inches) will then determine what "loss" or slip is occurring, expressed as a percentage. Typically the lower the better, and higher % can indicate an incorrect prop selection, amongst other things (sometimes you have the correct prop but something like algae growth is inducing more drag than normal). In your case, a 4-blade or larger diameter 3-blade will help with lower slip %, but that will also come at the expense of speed. These are some of the tradeoffs you will have to balance when making a prop determination.

There is a lot of information out there, on this site and internet. I would encourage you to understand as much as possible as this can really help you understand why certain props are or aren't working for you. People will throw out a lot of recommendations but only you will really know when you've achieved your best prop, based on the hard data and well as "feel". Sure we can say Yamaha Stainless Steel Pontoon 14x12 or Yamaha Aluminum Talon 13.5 x 14 but you'll need to be equipped to know how to gather the right test data and judge how optimal that selection was.
 
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Potomacbassin’ said:
There seem to be a lot of threads for 115hp motors that you can search through - I would start there. Use other people's time, money, failures and successes to your advantage. You may not find a perfectly matched situation but can at least give you a good starting point.

That being said, with only two toons your boat will be plowing a lot of water i.e. not really getting up on a good, high plane like with a tritoon. Add in the additional weight of the sea legs, and my non-expert advice is to seek out a prop that has more blade surface area - you can either try a 4-blade prop or a larger diameter 3-blade. By doing so this allows the prop to overcome the drag and weight of your boat and turn as much of that thrust into forward motion, instead of wasted and spilling off the blades.

You may read or hear the term "slip" which is basically a % of lost theoretical forward motion for a given pitch. So if your prop is a 13p, it should move forward 13 inches per revolution in a perfect, theoretical sense. Your actual observed forward motion (lets say 12 inches) will then determine what "loss" or slip is occurring, expressed as a percentage. Typically the lower the better, and higher % can indicate an incorrect prop selection, amongst other things (sometimes you have the correct prop but something like algae growth is inducing more drag than normal). In your case, a 4-blade or larger diameter 3-blade will help with lower slip %, but that will also come at the expense of speed. These are some of the tradeoffs you will have to balance when making a prop determination.

There is a lot of information out there, on this site and internet. I would encourage you to understand as much as possible as this can really help you understand why certain props are or aren't working for you. People will throw out a lot of recommendations but only you will really know when you've achieved your best prop, based on the hard data and well as "feel". Sure we can say Yamaha Stainless Steel Pontoon 14x12 or Yamaha Aluminum Talon 13.5 x 14 but you'll need to be equipped to know how to gather the right test data and see judge how optimal that selection was.
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Thank you very much, Will do and report back!
 
JW, typically I think you're going to find that SS is not the best choice under 150HP as it will not really improve your performance but only cost you more money. That said, welcome to the Bennington family!
 
JohnWestlund said:
Hello, Everyone I need some advise from the pros! I have a 2015 22GS Pontoon with Sea Legs. I wanted to update to a stainless prop. The Original prop was a 13.50 x12-K . I could never get more than 22 mph- I tried the Solas 13.75 x15 SS . My RPM dropped as expected but it had cavitation really bad at 3/4 throttle . The sea legs weigh 300-350 pounds ( Both props were 3 Blade) what do you recommend I try?
Click to expand...
115HP Yamaha SHO Prop Pitch? | Club Bennington (benningtonmarine.com)

Just went through this^^

1 pitch increase is huge, cant imagine a 3 pitch increase on a 115. Out of the 4-5 props I've tried, the 13.5 13P or 14P 3 blade Talon works the best. Mine also came with a 13.5 12P.

The biggest thing I learned recently is that larger diameter I went on mine sucked more air than a FA-18 Hornet. Getting the prop blades any closer to the ventilation plate did not help me in trimming the front out of the water at speeds. I lost between 22-25% of my trim ability which decreased my top speeds.
 
gotnitro said:
115HP Yamaha SHO Prop Pitch? | Club Bennington (benningtonmarine.com)

Just went through this^^

1 pitch increase is huge, cant imagine a 3 pitch increase on a 115. Out of the 4-5 props I've tried, the 13.5 13P or 14P 3 blade Talon works the best. Mine also came with a 13.5 12P.

The biggest thing I learned recently is that larger diameter I went on mine sucked more air than a FA-18 Hornet. Getting the prop blades any closer to the ventilation plate did not help me in trimming the front out of the water at speeds. I lost between 22-25% of my trim ability which decreased my top speeds.
Click to expand...
Good point Nitro -

John I left that part out, depending on your motor shaft length (20" vs 25"), mounting height and how the stern rides in the water a larger diameter could also vent, especially on turns.

My boat is very stern-heavy due to a larger motor and upgraded fuel tank, so I'm less susceptible to ventilation even with the motor mounted up two holes. But every boat will vary.
 
I suggest a 4 blade in a 13 pitch. RPMs for that motor should not exceed 6000.
 
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