Prop for a 18' Pontoon for more speed

[MNTooner]

Hi there,

Looking for a new prop for more speed. Right now loaded when I run at 3/4 throttle I get 10 mph(GPS) at 5400 rpm. I can open it up and hit 6200 rpm but I wasn't comfortable reving it that high and letting it run see how fast it would go. With just me and a six year old I get 16 mph at 5400, 3/4 throttle. I am looking to go to an 11 or 12, but I'm afraid the 12 won't allow me to get to 5500 rpm at full throttle. Was going to stick with an aluminum 3 blade as I'm not sure stainless and 4 blade wouldn't just add too much complication to the equation. Any advice on the 12? The required info is below:

1)Performance issue you are trying to correct. - More speed (hoping for about 20 mph, maybe not possible?)

2) Current prop manufacturer, model, aluminum or stainless as a minimum. - Mercury, 87818A10(Black Max I think), aluminum

3) Current prop diameter and pitch (required). - 12 1/4 X 9

4) Wide open throttle RPM and speed with an average load (very helpful) - WOT rpm range is 5000-5500 but I can rev to 6200 rpm at full throttle. Speed with an average load is 10 mph at 5400 rpm

5) Engine/drive make, model, year, and HP - 2006 Mercury outboard, 50 HP, 2 stroke, 1.83:1, not a Bigfoot

6) Boat make model, year, length and weight - 2006 Sun Tracker Party Barge 18, 19' around 2700 lbs

Thanks,

Mark in MN

 

[Silvertip]

Re: Prop for a 18' Pontoon for more speed

The 50 HP two strokes came in two flavors -- Big Foot (has 2.33 gears) and standard (has 1.83 gears). If you have a standard motor, the prop is wrong as those motors run small diameter (10-1/4 inch props) because of the low gear ratio. (Now don't get twisted with the term low gear ratio -- 1.83:1 is a lower ratio than 2.33:1). In car lingo it would be a called a "tall gear". So which engine you have determines what series props you need. The Big Foot motor is designed with the bigger gearcase specifically for pontoons and work boats that have a lot of turbulence behind them and where prop ventilation is an issue (which just happens to be what you may be experiencing). A Big Foot motor on a pontoon will typically run a 14 x 9 pontoon prop. Big round ears is the best for optimum push. So we can't answer you question unless you tell us what motor you have. If it's a Big Foot it will say so on the cowl.

 

[MNTooner]

Re: Prop for a 18' Pontoon for more speed

The 50 HP two strokes came in two flavors -- Big Foot (has 2.33 gears) and standard (has 1.83 gears). If you have a standard motor, the prop is wrong as those motors run small diameter (10-1/4 inch props) because of the low gear ratio. (Now don't get twisted with the term low gear ratio -- 1.83:1 is a lower ratio than 2.33:1). In car lingo it would be a called a "tall gear". So which engine you have determines what series props you need. The Big Foot motor is designed with the bigger gearcase specifically for pontoons and work boats that have a lot of turbulence behind them and where prop ventilation is an issue (which just happens to be what you may be experiencing). A Big Foot motor on a pontoon will typically run a 14 x 9 pontoon prop. Big round ears is the best for optimum push. So we can't answer you question unless you tell us what motor you have. If it's a Big Foot it will say so on the cowl.

Mine is the 1.83:1, it is not the Bigfoot.

Mark in MN

 

[steelespike]

Re: Prop for a 18' Pontoon for more speed

Don't worry about diameter simply look up props for a 2006 50 hp 2/4 stroke non bigfoot the diameter will be right. Lower number pitches are available here in 9,10,10 1/2,11,11 5/8,and 12
I would try the Solas Amita 4 blade 11" pitch. Should lower rpm slightly more than a plain 11" Should improve overall performance.

 

[MNTooner]

Re: Prop for a 18' Pontoon for more speed

Don't worry about diameter simply look up props for a 2006 50 hp 2/4 stroke non bigfoot the diameter will be right. Lower number pitches are available here in 9,10,10 1/2,11,11 5/8,and 12
I would try the Solas Amita 4 blade 11" pitch. Should lower rpm slightly more than a plain 11" Should improve overall performance.

I will give that a try.

Thanks,

Mark in MN