Prop on my pontoon

[captmello]

Hi guys,

I was out on my toon (Listed in my sig) the other day and checked my speed (gps). I found I'm getting up to 27mph @ 5100 RPM with my Solas amita 13p, 4 blade prop. This works out to about a 14% slip.

I found these number to be about what I thought they would be.

So yesterday I was out and something reached up and took a bite out of my prop. I'm sure it is fixable, but the shop charges $70 to fix, and I can buy a new one for $120.

So I just wanted to see if anyone can think of any reason to switch to something different. There aren't a lot of prop options for me, but I just wanted to see if anyone had any comments/opinions.

Thanks!

 

[steelespike]

Re: Prop on my pontoon

I would say your performance is close to exceptional.
Hard to imagine even a change to a ss prop could result to much improvement.
If you don't have any ventilation/cavitation problems you may be able to raise the motor
to a point just before venting becomes a problem.Might add a little speed at no cost.
I say get a new Solas amita.

 

[Bamaman1]

Re: Prop on my pontoon

You're running 3-4 mph better than most 90's. Count yourself lucky.

Even though we see few 4 bladed props on pontoons, I would suggest you go back with the same prop. If you get ahead on money, have the old prop reconditioned and carry it for a spare.

 

[captmello]

Re: Prop on my pontoon

I would say your performance is close to exceptional.
Hard to imagine even a change to a ss prop could result to much improvement.
If you don't have any ventilation/cavitation problems you may be able to raise the motor
to a point just before venting becomes a problem.Might add a little speed at no cost.
I say get a new Solas amita.

Exceptional! cool. Thanks for the reply. My motor is at its lowest position...But I think I'll just leave it there.
i just went back and found my original prop thread. You were the one who suggested it. Good Work!!
http://forums.iboats.com/prop-questions-topics/new-prop-my-toon-471974.html
And shame on me for not posting back...But you can see I got 200-300 RPM more. I didn't have a GPS back then to compare speeds.

You're running 3-4 mph better than most 90's. Count yourself lucky.

Even though we see few 4 bladed props on pontoons, I would suggest you go back with the same prop. If you get ahead on money, have the old prop reconditioned and carry it for a spare.

3-4 mph better, hmmmm, I wonder why. I went back to the prop calc and checked to see what 24 mph would give me for prop slip, 24%. Is that amount of slip common on pontoons? I'm curious about why more tooners wouldn't try the four blades.

 

[steelespike]

Re: Prop on my pontoon

I do wonder if you were running down wind or with the current?
I would say that 20 to 24% is more typical.

 

[steelespike]

Re: Prop on my pontoon

I do wonder if you were running down wind or with the current?
I would say that 20 to 24% is more typical.
5500 at 27 would also produce about 20%.

 

[captmello]

Re: Prop on my pontoon

I do wonder if you were running down wind or with the current?
I would say that 20 to 24% is more typical.
5500 at 27 would also produce about 20%.

Wait a minute, maybe we aren't on the same page...

Here is the prop calc I'm using.

continuousWave.com: Whaler: Reference: Propeller Calculator

27mph @ 5100 rpm, 13p prop, 2:1 ratio...

I may have had the wind to my back, but no current in the lake.

 

[steelespike]

Re: Prop on my pontoon

I too get 14% with 5100, 2.00, 13" 27 mph.
But if we assume your tach is wrong and insert 5500 rpm we get a more likely 20% slip.
As far as wind goes a little assist down wind probably isn't much but upwind with a pontoon could slow things considerably.

 

[captmello]

Re: Prop on my pontoon

I too get 14% with 5100, 2.00, 13" 27 mph.
But if we assume your tach is wrong and insert 5500 rpm we get a more likely 20% slip.
As far as wind goes a little assist down wind probably isn't much but upwind with a pontoon could slow things considerably.

Ah, now I see what you're saying. Since I don't know how to hook up my shop tach to my outboard I won't worry about it.

Thanks again for your input, past and present.