New Toon owner with prop ?

[Rollinsj]

Hello everyone, I am a new pontoon owner and I am enjoying every moment I am on it. I have a 20' Starcraft with a 91' 48hp spl Evinrude, 11 3/4 x 17 prop, WOT 5400-5500 rpm @ 17.5 - 18 mph with 2 adults and 2 children. My question is would I benefit by switching to a pontoon prop and a different pitch for better fuel economy? thnks

 

[MH Hawker]

Re: New Toon owner with prop ?

I would think its exactly where it should be on RPM and speed. Open a cold one and enjoy the ride

 

[5150abf]

Re: New Toon owner with prop ?

Sounds like you are right where you need to be, you prop an outboard for an rpm and the speed falls where it does, on your engine you are exactly where you need to be with that.

Get with the rpop gurus and see if maybe you can get the same rpm with a bigger diameter smaller pitch prop, btu I don't knwo if you can get any more speed, pontoons a terribly inefficient hulls.

 

[Part-time]

Re: New Toon owner with prop ?

A pontoon (high thrust) prop will be better if you plan on increasing your load.
If you don't plan on ever taking more people aboard or loading up for a weekend of camping you will be fine with what you have.

 

[Rollinsj]

Re: New Toon owner with prop ?

Thanks for the info guys, I will stay with what I have due to there will only be 4-6 people on board at most. I'm just used to my old boat running forever on 12 gallons. Thnks again.

 

[Part-time]

Re: New Toon owner with prop ?

Don't forget... you're not just pushin 2 logs through the water. You now have the aerodynamics of a brick to push into the wind!

 

[Rancherlee]

Re: New Toon owner with prop ?

I think your turning the correct RPM by accedent. Your boat/engine combo screams for a 11 or 13 pitch prop. Either you have extremely excessive slip or your tach lies to you.(incorrect setting?) Same engine/prop pushes 16' fishing boats ~30-32mph with 10% slip

 

[5150abf]

Re: New Toon owner with prop ?

16' fishing boats are mono hull which is hugely more efficient than pushing 2 toons through the water, it is the difference between a planing hull and a pair of wave cutting hulls, a mono hull rides on top of the water, a toon goes through it.

 

[Rancherlee]

Re: New Toon owner with prop ?

Yes, but he has a 2.42 gear ratio and the calculated slip is dang near 50% which is excessive, even for a pontoon. Even with an overloaded pontoon I haven't seen slip that bad unless it's blowing out. The 50hp (same block/case) on my grandpas 30' work toon pushes it 18mph empty with a 13x11 prop and 10mph @ 4800rpm with 4000# of navigational buoys on board which is over capacity. Thats a worst case scenario and even then it's not as much slip as he is seeing. 20-30% is to be expected on a pontoon, near 50% and something isn't right.

 

[Rancherlee]

Re: New Toon owner with prop ?

Another thought, my 79' Johnson 55hp used a 10 pole tach setting, not a 12 pole like the majority of outboards. The 55hp basically became the 48spl after Horsepower ratings changed to prop rated in the mid 80's

 

[steelespike]

Re: New Toon owner with prop ?

I don't think your tach is accurate.It is reading too high I think your should be running a about a 13"pitch.
You should verify the tach.Perhaps borrow a shop tach or get an induction tach like the Tinytach.
Don't do a prop till you verify the tach. I think the 17 is actually higher than what you might find on a much lighter faster boat.
As suggested you may want to check the tach setting.

 

[Rollinsj]

Re: New Toon owner with prop ?

Thnks for the info everyone, everything I have researched says I should go with a different prop. I will check the rpm somehow then go from there.

 

[Brads Cat'N Around]

Re: New Toon owner with prop ?

Thnks for the info everyone, everything I have researched says I should go with a different prop. I will check the rpm somehow then go from there.

I have a 1988 24' lowe with a 48Hp spl Envinrude, I know mine will run 30-35 mph no problem. Planes very quick and runs great. I am unsure of pitch on prop, I assume it is factory prop. I bought the boat used. I also have the square toons on my boat. I have heard that they make a difference as far as planing and speed are concerned.

This is my first pontoon in 40 years and my wife and kids LOVE IT. I just registered, and have been reading boating threads for a couple years. THANK YOU TO ALL FOR POSTING YOUR VALUABLE INFORMATION.

 

[MH Hawker]

Re: New Toon owner with prop ?

Brad ,,that seams like a very high speed on a 24 ft with 50 hp is that a gps speed.
I would of guessed more around 17 to 20 mph.

 

[Big Bubba]

Re: New Toon owner with prop ?

MHHawker,
BradsCat'N Around pontoon boat must be light as a feather if he can do 30 to 35 mph with a 48 horse outboard on a 24 foot pontoon boat. I agree with you MH Hawker that his should only be running around 20 mph with a very light load.

 

[Rancherlee]

Re: New Toon owner with prop ?

I could see 35mph, on a Single 24' tube with a 48spl hung on the back and a single outrigger for balance......

 

[muskiemike12]

Re: New Toon owner with prop ?

He must use the metric system. I could maybe see 35 kilometers per hour.

 

[Silvertip]

Re: New Toon owner with prop ?

I have done a ton of research on the 40/50 HP Evinrude and even on a relatively light 16 foot fishing boat, it is a toss-up as to whether a 11-3/4 x 17 (no cup) or a 12-/14 x 15 (cup) is the best prop. I tested lots of props and always came back to the 12-1/4 x 15P. One thing is certain -- a pontoon with this motor should NOT have a 11-3/4 x 17P prop. Step 1 is to check the back of the tach and make sure the calibration dial is set to 6P (you have a 12 pole alternator). Turn the dial back and forth a few times to burnish the contacts and then re-set it. Then verify speed. Then verify that "blow out" is not an issue. Verify that the engine is mounted full down on the pod. If it is mounted too high you will experience high rpm and tons of prop slip. You are not driving a hot rod so just install the motor full down. Motors on pontoons operate in very turbulent water and need all the bite they can get.

 

[Bamaman1]

Re: New Toon owner with prop ?

To answer your question, you're where you should be with the 48 hp motor and 20' boat. There's not much you can do in the prop department that would increase speed. Chances are you'd just be lugging the engine, which is not good for it.

As long as you're pulling the redline, be happy. A larger engine would be required for more speed.

 

[Brads Cat'N Around]

Re: New Toon owner with prop ?

Sorry guys, speed is more like 20-25. I was guessing, and it is very light load. I just redecked the boat last year, and only have captains seat and helm in boat at this time. I will be putting in the back half benches and corner seat later this year. I am going to keep the front half open for Catfishing. That is why I am looking for a hard top, do you think the hard top will slow it down?

Thanks