These speeds seem right 24' 115 22mph

[smoedog]

I just bought a 1993 24' Aquapatio. Its got a 115 Yamaha 2stk on it. It has a 13.5x15 solaris SS prop. At 4K I am getting a rock solid 18 on GPS. WOT is 4800-4900 and can get 22. Everything I have seen is the WOT range is 4500-5500. 22 just seems low. Whats everyone think?

 

[lakegeorge]

Re: These speeds seem right 24' 115 22mph

I just bought a 1993 24' Aquapatio. Its got a 115 Yamaha 2stk on it. It has a 13.5x15 solaris SS prop. At 4K I am getting a rock solid 18 on GPS. WOT is 4800-4900 and can get 22. Everything I have seen is the WOT range is 4500-5500. 22 just seems low. Whats everyone think?

Check the Yamaha site to see what they are getting on your engine. You can also go on the web and type in pontoon boat tests and you will find a few sites that have tested all kinds of toons.
22 mph is low.

 

[smoedog]

Re: These speeds seem right 24' 115 22mph

specs I have read is 4500-5500 wot rpm range.

 

[RustyShackleford]

Re: These speeds seem right 24' 115 22mph

I think it should be higher than that, just comparing to my 22' boat at WOT with about 1100 lbs of guys and gear I can do 17MPH, and I only have 60HP. Even if you had as much wait as me at the time, I would surely expect your almost double HP to make more than a 5MPH difference. I may just be talking out my *** though since I am a newb. Just wanted to offer 2cents if it helps.

Your 4900 does fall in their range, the higher end may be with it trimmed up.

What's the diameter on your toons?

 

[Bamaman1]

Re: These speeds seem right 24' 115 22mph

I have a 24' Starcraft pontoon with the Yamaha 115 hp 2 stroke.

I would think you'd need to make sure your engine is running at the right height on the transom. Until it's right, experimenting with propellers is a moot point. At a cruise speed, you should be able to look over the transom and see the anticavitation plate without a bunch of splashing over it. When the motors are too low, the plate is obstructed with spray. When they're too high, you get easy cavitation when making a tight turn or when too many people get in the front seats.

Your boat is a little slow. I don't have a speedometer, but my Yammie 2 stroke accelerates like a bass boat--strong, conservative horsepower. I am planed off @ 2500 rpm's and I seldom even run over 3500 rpms with a 15 pitch prop.

If your motor height is correct, you may need to put a 13 pitch prop on it.

 

[smoedog]

Re: These speeds seem right 24' 115 22mph

I looked at it this morning and the cav plate is maybe 4 inches below the bottom of the transom. I'll post pictures later but I am thinking bringing it up 2 holes

 

[lncoop]

Re: These speeds seem right 24' 115 22mph

Speed and RPMs both seem low, and that's quite a few to make up with prop and engine height experimentation. Have you ruled out engine issues? I know you're a mechanic, so I assume you checked compression before you bought, right?

 

[BobGinCO]

Re: These speeds seem right 24' 115 22mph

I dropped to a 13" pitch, and it put my RPM's and MPH's in the zone I wanted (6,200 and 24). But that is because I run at 5,000 foot elevation, where my "115" is only getting about 95 HP.

 

[crb478]

Re: These speeds seem right 24' 115 22mph

I have a 1998 24 foot crestliner pontoon with a 86 yamaha 115 and with clean toons in smooth water I have run 31 mph on gps at 5400 rpm. I am running a 13 pitch four bladed prop and the motor (20 inch shaft) is as low as it can go. I think you can get more speed out of yours with the proper set up.

 

[smoedog]

Re: These speeds seem right 24' 115 22mph



Should I try raising the motor?

 

[Okieboatguy]

Re: These speeds seem right 24' 115 22mph

Seems slow, or I am able to run faster than most. I have a 2000 21' Voyager tri-toon with a 2002 90hp Evinrude. I run a 14"x 13P and I will WOT at 5400 rpm at about 38 MPH on the GPS on calm water, (My son said he hit 40 on glass and by himself). I will plane up at 2200 RPM at 14 MPH, but can stay on plane at 8-9 MPH, and run all day wakeboarding at 18 mph at 2500 rpm.

 

[smoedog]

Re: These speeds seem right 24' 115 22mph

well you have a tri-toon big difference

 

[Silver Eagle]

Re: These speeds seem right 24' 115 22mph

Check your speed with a hand held GPS ,Those boat speedometers aren't worth crap.

 

[smoedog]

Re: These speeds seem right 24' 115 22mph

I stated in my original post the speeds were by gps

 

[rogerwa]

Re: These speeds seem right 24' 115 22mph

I think if you were to try a 13P prop you would be in better shape. I have a 25' toon with 25" tubes pushed by a 115hp V4 Evinrude and I get 5200 RPM at about 24mph. I think I can do better if I can get the RPMs up. I am swinging a 13 7/8 13P Evinrude Hydrus prop which has larger blades and cupping to keep the traction.

Your numbers show you are getting 36% slippage (assuming a 2:1 lu ratio). I am running at about 25% slippage.

How big are your toons and how deep are they in the water. Could they have water in them that would make you run heavy?

 

[smoedog]

Re: These speeds seem right 24' 115 22mph

Well found out this past weekend my prop is beginning to spin. Not much but it is spinning.

So I was looking at Solas Props, Now the question is Amita or Rubex What is the difference? Any other inexpensive 13p props for a Yamaha that will work for a pontoon?

 

[rogerwa]

Re: These speeds seem right 24' 115 22mph

When you say spin, do you mean that the hub is slipping or is it losing bite?

 

[smoedog]

Re: These speeds seem right 24' 115 22mph

Sorry, hub is slipping. Noticed it when I pulled the prop off and saw some radial wear between the prop and thrust washer. Confirmed by marking the position of the cotterpin in relation to the prop. Ran it, and it had moved.

 

[lakegeorge]

Re: These speeds seem right 24' 115 22mph

Well now you know why it's running slow. A prop change should get you what you want.

 

[Bob_VT]

Re: These speeds seem right 24' 115 22mph

View attachment 162773

Should I try raising the motor?

If there is a correlation between regular hulls and pontoons maybe a pontoon expert will chime in.

YES in my opinion you are LOW. The plate should be at least even if not even up to an inch high in relation to the bottom of the hull.

You only need to remove the top bolts and loosen the bottom ones..... a block of wood and a small hydraulic jack to lift the motor up a hole or two.

BTW that is a nice ss prop so if I were you I would get a new hub installed into it for re-sale or keep as a spare.