New prop for my Toon

[captmello]

I only have one prop for my toon, listed in my sig.

I want to pick up another prop so I have a spare/alternate.

The current prop is an aluminum 13.75x15, and is the original prop that came on the 90 hp Johnson.

The previous owner said he was getting 45-4800 wot, which is on the low end of the proper RPM, max being 5100 i believe.

Are there props made for pontoons, or set up specifically for toons...?

What do you guys suggest I look for in my new prop? I plan to do cruising and tubing.

thanks.

 

[PROPer]

Re: New prop for my Toon

You are going to need to move down in pitch to atleast a 13 pitch in effort to get those engine RPMs up to where they need to be.

 

[captmello]

Re: New prop for my Toon

You are going to need to move down in pitch to atleast a 13 pitch in effort to get those engine RPMs up to where they need to be.

Okay, so would you suggest the same diameter? There is quite a variety of props to use.

Do you think it should be running up to the 5100 max at wot? Do you think its over propped now?

 

[steelespike]

Re: New prop for my Toon

My info indicates you need to be at 5,600. I think you should test it your self confirm your numbers.If you need 800 more rpm an 11" seems in order. See if you can find a 4 blade 11 with
a good diameter. You may want to confirm the motor is in excellent tune and the throttle opens all the way.

 

[captmello]

Re: New prop for my Toon

My info indicates you need to be at 5,600. I think you should test it your self confirm your numbers.If you need 800 more rpm an 11" seems in order. See if you can find a 4 blade 11 with
a good diameter. You may want to confirm the motor is in excellent tune and the throttle opens all the way.

Thanks for the reply.

I checked my owners manual and it says Max WOT RPM is 4500-5500. I agree however that I need to test drive it first.

I guess I was also trying to find out if there was a specific type of prop that works better on pontoons. I thought I had read that, but could be wrong.

If what the previous owner said about the current RPM's, I may consider an 11", 4 blade, prop Like steelespike suggested for those days out with the kids tubing, and use the 15" for cruising at lower RPMs. Does this make sense?

 

[captmello]

Re: New prop for my Toon

I was just checking the iboats store for props. They do not offer an 11p, 4 blade prop. They do offer a 13p, 4 blade prop with a 13.25" diameter.

Any thoughts on the 13p with the smaller diameter?

 

[steelespike]

Re: New prop for my Toon

No, cruising at lower rpm (when induced by a prop change) lugs the motor motor.Actually less efficient and could cause premature repair problems.
Marine engines are straining like they are going uphill all the time when you run too much pitch its like pulling your boat and trailer up a steep hill in overdrive.
The motor needs to rev freely within its rpm range.Your best cruising mileage with your toon is probably 6-7 mph And some toons will do better at that speed than a runabout.
Few have the patience to run at that speed.

 

[steelespike]

Re: New prop for my Toon

I was just checking the iboats store for props. They do not offer an 11p, 4 blade prop. They do offer a 13p, 4 blade prop with a 13.25" diameter.

Any thoughts on the 13p with the smaller diameter?

Usually a larger diameter prop will have less venting issues but a 4 blade also will likely have less venting issues than a 3 blade. Unfortunately I don't think a 13 is low enough to solve your problem.
Also when you go from a 3 to a 4 there is usually a slight reduuction in rpm(same pitch to same pitch) from the slight increase in drag.When dealing with props nothing is carved in stone there are sometimes unexpected results.

 

[captmello]

Re: New prop for my Toon

Hi guys, well, I finally was able to get out on my Pontoon for a test run with the current prop.

At WOT, I was getting about 4800-4900 RPM with the 13.75x15p prop.

So being at the low end of the Max range, I'm going to get a new prop in hopes of picking up more RPM. I am going to purchase a Solas Amita prop. They offer a new thrust washer for another $20+, is it necessary to purchase a new thrust washer? Or can I use the one thats on there now.

Do you guys have any other suggestions? I'm thinking of going with a 13p, 3 blade, but could also go down to an 11p if it seems necessary. I'd really like an 11p, 4 blade, but that is not available, at least not on iboats.

Any more advice is appreciated.

 

[steelespike]

Re: New prop for my Toon

I lean toward the 13" 4 blade.It will resist venting should have less slip
and will have better control around the dock.See how it does and then consider a prop for tubing if necessary.

 

[captmello]

Re: New prop for my Toon

I lean toward the 13" 4 blade.It will resist venting should have less slip
and will have better control around the dock.See how it does and then consider a prop for tubing if necessary.

Hmmmm, you realize this goes against what you said in post #8. However, I like the idea of going with the 4 blade. I was scared off by your earlier comments, and realize I may not get more than 100-200 rpm.

Fwiw, the hole shot with the 15p isn't too bad and the previous owner used for tubing, so I'm optomistic.

Barring any other objections, I'm going to order the 13p, 4 blade.

Thanks for the input and I'll update my performance numbers once I get the new prop.

Oh, BTW, do I need to buy a new thrust washer to match the new prop?

 

[steelespike]

Re: New prop for my Toon

I like the venting resistance and control of the 4 bld over the 3 blade.And you could have the 13 repitched if necessary. Thrust washer may or may not work for convenience I guess a new washer is in order. Watch the old washer it may stick to the old prop and be lost in the shuffle.