Prop suggestions

[EricStarr]

I have a 21' suntracker pontoon with a 40hp mercury and was wanting to change props to see if i can maybe get a little more speed out of this under powered boat or not it runs almost 5900-6000rpm right now at wfo any suggestions would be great

Prop now is a quicksilver 11 1/4 10" pitch 3 blade

 

[91kuhndog]

Re: Prop suggestions

Eric,
I think you're stuck with what you have. The first thing you have to look at is power to weight ratio on a pontoon. A 40 on a 2500# boat limits you to slow going. You might try going stainless, the same size, but for the money, it's a lot for a little gain. the last thing you want to do is reprop and lug the motor....you'll cook it. You want to be at the high side of your RPM range for that motor. Another option, wait until the off season and repower with a used motor. I have 2rental pontoons in Ohio and I run Johnson 70's on both so the parts I keep are interchangable. They'll push a 20' at about 30mph with a stainless wheel on them.

 

[steelespike]

Re: Prop suggestions

I don't think its possible to push a plain toon to 30 with a 70 hp.
As far as your tracker with a 40 18 to 20 might be possible.Do you have any
speed figures now?You could put a skin on the underside. and add a pod or 3rd log.
The 3rd log is pretty effective adds flotation. and gets up better.The log might get you 3 to 5 mph.the skin 1 or 2.
Pontoons produce high slip numbers a same pitch solas amita 4 blade should reduce that and resist ventilation as well. Also will respond better at the dock, stopping, reverse etc.

 

[EricStarr]

Re: Prop suggestions

Right now its pushing only 15 to 18 according to my gps will a skin on the bottom really help that much and what type material should i look at getting

 

[steelespike]

Re: Prop suggestions

What year Merc?
Unfortunately I don't have info on a skin but you could google it.
There are probably aftermarket "kits" or materials a person could apply.
The Solas I spoke of is about $100 and should surely improve your speed slightly
while inproving your handling.The skin would probably gain about the same and obviously be a pain to apply compared to a prop change.Don't expect amazing results but I feel a 4 blade will perform more predictably than a 3 blade.

 

[EricStarr]

Re: Prop suggestions

Its a 1999/2000 model runs real good. I have some sheets of stainless steel but i think it would add way to much weight but i will look around and see what i can find. I found that prop on-line and your right on about 100 bucks fixen to order me one. Man i sure do appreciate all your input.

Thanks,

Eric

 

[91kuhndog]

Re: Prop suggestions

Just make sure the toons you have are clean, free of crud. I use scotch brite pad while at the sandbar swimming. It works pretty good and keeps the toons looking good. Clean is fast; if you leave it in the water all summer, grass is unavoidable. My 18' toon with 70 w/stainless GPS's at 29.2

 

[EricStarr]

Re: Prop suggestions

Man i spent about 3 days on my toons mine stays on the trailer i used toon bright then polished the crude out of them they look great.

 

[EricStarr]

Re: Prop suggestions

Man the 4 blade that i bought was the same size as the 3 blade had a world of difference the 3 blade is much better i guess i need to make a drop in the pitch from a 10 to a 9 because w/ the 4 blade i was only hitting 4200rpm and my top speed dropped 4 mph what do yall think should i drop to a 9 or maybe a 8 pitch.

 

[steelespike]

Re: Prop suggestions

A 2 stroke is rated at 5,500 a 4 st 6,000.Seat of the pants;
It appears the 10 had a tremendous amount of slip even for a pontoon and the 4 sure solved it.On a smaller motor 1" for 200 rpm doesn't apply as much. It is likely more, but I don't think 1" will get us 1300 rpm.So an 8 makes sense.There is only one prop smaller than the 8.If it is underpropped your better off than having to lug
the motor.

 

[EricStarr]

Re: Prop suggestions

Is it going to make any difference that i went from a 11 1/4 on my old three blade to a 11 4/5 on the 4 blade prop i bought i did not see a 11 1/4 4 blade prop when i was looking.

 

[steelespike]

Re: Prop suggestions

Diameter follows the design. And doesn't usually effect the performance.
The difference might produce a slight reduction in rpm but surely not much compared to 1800 rpm loss.Without gettin to detailed your 40 with a 10 at 6000
rpm would probably be going around 40 mph. I think you can see there is a lot of slip on the pontoon.

 

[EricStarr]

Re: Prop suggestions

This is what i found is the 4 blade going to be ok you think http://boatpropellers.iboats.com/Me...?rotation=Standard&**********=349237225&cart_