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Performance issues

Nautical said:
I'm going to bet you'll end up with a 17 or larger pitch prop when this is all said and done. Maybe even a 19.
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I run a 15.5x17 on my merc 150 22sx loaded with coolers and 8 people and on smooth water were hitting 35mph at 5000rpms
 
My hope is to do 30 MPH with around 3500 RPMs. I need to try a few props to hopefully find this performance.
 
based on that performance would would expect well over 50MPH with a 300HP motor.
 
Dont forget to take the weight of the boat into consideration ,a Q is much heaver than an S
 
Finally able to test two props.

Here is the setup.

25' QSRFB with cladded arch and raised helm
F300XCA Yamaha (300 HP)
40 gallons of gas
2 Crew
88˚F

15-3/4" diameter x 15" pitch
0-20 mph 5.6 sec
3000 RPM 18MPH
4000 RPM 26 MPH
5000 RPM 34 MPH
MAX rpm 5700@41 MPH

15-1/2" diameter x 16" pitch
0-20 mph 4.8 sec
3000 RPM 19 MPH
4000 RPM 26 MPH
5000 RPM 36 MPH
MAX rpm 5800@45 MPH
Wanted to test a 17" pitch propeller as well but dealer didn't have one in stock to test.

Can anyone else post some performance numbers with their setup. Curious to see if I have the correct prop and if my motor height should be adjusted.
 
What brand of props are they? I and many others swear by the Mercury Enertia.
 
I have a 23 RCW with Yamaha 300XCA and it is mounted in 2nd hole from the top. I spin a 15.5~17 Saltwater Seies II prop. I consistently hit 47 MPH with proper trimming and occasionally 48 MPH. RPM at those speeds 5800 to 5900. My take is you will be spinning 17 to 18 pitch prop and your top end will be 42 to 45 MPH. You have a much heavier boat than I do.
 
Prop is a yamaha saltwater series II. I don't think Merc props are designed for yamaha and it's probably a bad idea for motor warranty.

The prop I tested today was 15-1/2 x 16 and produced 45 MPH trimmed. Hole shot was impressive too. Motor is mounted as low as it can go (top hole). I liked the result and the hole shot. Only concerning thing is the length of prop spray behind boat when pulling a skier/tuber. Not sure if a 60'/75' rope is long enough to get rider beyond prop spray. Also noticed the the ventilation plate is not visible when on plane. Don't think it should be but I am questioning motor mount height.
 
Dahbull said:
Prop is a yamaha saltwater series II. I don't think Merc props are designed for yamaha and it's probably a bad idea for motor warranty.
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Prop manufacturer is not a factor on impacting motor warranty. I’d be flexibilie which types of props you experiment with when dialing in your boat. It’s not really an issue of Merc props not designed for Yamaha’s or vis-versa.

Although some props are often paired with certain motors in theoretical use/design, pontoons offer a significant degree of unpredictable variance due to length, hull, layout, weight, balance, etc... As a result, sometimes props react with different pontoons in unpredictable ways - sometimes good, sometimes not.

You got some Yamaha’s on here working better with the Merc Enertia’s, but Merc’s sometimes running better with certain Yamaha props, etc. Just the nature of the beast.
 
Well said, Jeff. It's not an exact science. My dealer could not understand how I got better holeshot AND more top speed when I went from a 13p to a 15p. He said it was impossible. Not sure why he thought I'd lie about that, but oh well.
 
Hey guys, here is my issue. I have a new GSRFB with a F300. Max speed is 40.5 mph at just barely above 6k rpm and pretty much just over 50% trim. This is regardless of any amount of fuel or people. My prop is SWS 15- 15 3/4 (think its 15 3/4) 2013 GSR 2550 with a F250 on it. The old boat is the exact same top speed as this one. My dealer says this boat should be doing 48 and i am way off that. At this point dealer is calling the factory.
thoughts? (wonder if i have leaking toons!) How does a guy tell if there is water in the toones?
 
oldredm3 said:
Hey guys, here is my issue. I have a new GSRFB with a F300. Max speed is 40.5 mph at just barely above 6k rpm and pretty much just over 50% trim. This is regardless of any amount of fuel or people. My prop is SWS 15- 15 3/4 (think its 15 3/4) 2013 GSR 2550 with a F250 on it. The old boat is the exact same top speed as this one. My dealer says this boat should be doing 48 and i am way off that. At this point dealer is calling the factory.
thoughts? (wonder if i have leaking toons!) How does a guy tell if there is water in the toones?
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You should be spinning a 16 or 17 pitch prop on that setup.
 
You have a longer (heavier) boat and the fiberglass of the fastback (more weight). You only went up 50 hp. My $.05
 
For the most part pontoons have a terminal velocity. I would say for most that is 45-50 unless you have some serious HP and X2 of them.
 
Well, I agree with each of the three statements above. By adding weight, but only 50hp, you are probably off setting a lot of potential gain. However, your prop certainly seems a bit small for that motor if you are trying to max performance. I would test out both the 16 and 17 mentioned by Ray above. My guess is the 17.
 
oldredm3 said:
Hey guys, here is my issue.... thoughts? (wonder if i have leaking toons!) How does a guy tell if there is water in the toons?
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Use the search feature and search "water in toons" or "water in pontoons" or "water in log," etc. There have been several threads here over time discussing the issue and how to diagnose.
 
I would think that thing should be running at least a 17 pitch for 300hp. My 200 can push a 16 pitch.
 
we have a Verado 350 on our 25 QSB. The prop that came on the boat was an Enertia 14.5 x 17p 3 blade stainless steel. Top speed reached was 50.6 MPH GPS. Changed to a revolution 14.5 x 17p 4 blade prop. Lost a few MPH on the top end but gained better low end control, better hole shot and a little better fuel economy...
 
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