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2250 GBR Prop Question

whitacre

whitacre

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We just purchased a new 2250 GBR with a Yamaha 115 4 stroke and a 13.25 X 17 prop. My top speed is only about 21 MPH. My dealer says I should get 25 to 26 MPH. I think I should get at least 25 and maybe even a little more. My question is... Is the 13.25 X 17 prop the best for my set up? Would I be better off getting a larger diameter (maybe 13.75 or 14), or perhaps a different pitch of 15? Looking to get a little more performance. Any advice would be appreciated.

Thanks.
 
Congrats on the boat and welcome aboard!

What hull configuration do you have? Two 25 inch tubes? Or maybe the smaller 23 inch tubes? I could see the 23 inchers riding low enough in the water to only get you that for a max speed, but I've not seen one person on this site with the small tubes yet. Your prop size doesn't feel right to me, but I'm no expert. Some of the other guys here will help you with this.

I have a 13.75 x 15p and the express package and get 35 mph from our 115.
 
Kaydano,

I have two 25 inch tubes. I get to my top speed of 21 at about 5500 rpm.
 
Hey Whitacre, yeah, you should be getting more for sure, my 90hp did 22-24. Take a look in the topic "list your specs here" and read through for what other people had for numbers, it's a great information tool.
 
17P isn't the right pitch for that motor. I would guess a 15P. Not sure on the diameter but I would think a little higher would be better.
 
I agree, too much pitch.
 
My original thought was to go with something like a 13.75 X 15. Would that be more likely to give me a little more MPH?
 
On my RL with a Yamaha 115 it came with an aluminum 13.5 x 15 and I get 26mph. Have a feeling that if you experiment you could even eek out a little more but for me 1 or 2 MPH is just not big a deal so I am happy with what I have
 
Speedo or GPS speed?? Turning a 17p @ 5500 rpm's should put you well over your target of 25mph. I would be looking at a prop with close to 14" diameter (3 blade) and 13-15p for best all around performance if you tend to have a few people on board most of the time. The F115's like to run in the upper rpm range @ WOT, close to the limiter at 6250. Prop it for 6K +or- and your engine will reward you with better performance and fuel economy.

After much testing of both stainless and aluminum props, we chose to stick with aluminum solely because of the gearcase clatter with the stainless props on our F115. We ran a Solas Amita 4 blade aluminum 13.25 x 13p with excellent results. The boat ran a consistent 28+ mph @ 6100.
 
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The speed I am getting is measured by GPS. I also noticed that my prop is a little dinged up around the edges of one of the blades. Could the rough edges be causing me to lose about 5 MPH?

Ben & Suzy, sounds like if I were to try a prop with less pitch I should be able to increase my RPM. Will I get the best performance with RPMs as close to 6200 as possible?

Sorry to ask so many questions, I'm new to boating and trying to learn as much as I can.

Thanks.
 
That depends on how bad the "dings" are, but you typically wouldn't lose much speed due to a few nicks. It's more likely to cause a bit of annoying vibration. Dirty logs will definitely lose 5mph in a big hurry though, if it sits in the water. A 2" change in pitch with the same type of prop should equate to ~200 rpm difference so you'd really want to push it up closer to 6250 as Ben and Suzy advised.
 
I guess that depends on your definition of "a little dinged up" lol.

I'd prop it to run anywhere between 5800-6100 rpm's. The limiter is at 6250, so 6100 rpm's with a few folks on board is good. You'll be right at the limiter alone. Check the Bennington / Yamaha performance bulletins to see which prop is used on the test boats. Most will run a Yamaha 13.25 x 14p, but there are other brands that work well. The aluminum Mercury Black Max and Solas Amita perform very well.
 
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