Proper Prop for 24' pontoon

walt0244

Recruit
Joined
May 5, 2013
Messages
1
I am trying to determine the correct propeller for the following, any help would be appreciated.

1) Performance issue you are trying to correct. - trying to determine the proper prop
2) Current prop manufacturer, model, aluminum or stainless as a minimum. - Mercury A40l 13P
3) Current prop diameter and pitch (required). - 10" 13 P
4) Wide open throttle RPM and speed with an average load (very helpful) - Not sure
5) Engine/drive make, model, year, and HP - 1989 Mercury 45HP classic 50
6) Boat make model, year, length and weight - 1990 Godfrey Sweetwater - length = 24' weight Weight with gear and people approx 3200#
 

jestor68

Commander
Joined
Jun 12, 2012
Messages
2,308
Re: Proper Prop for 24' pontoon

If you visit the Mercury prop selector(it has a pontoon category), and plug in your info, it will suggest a 9 pitch in Black Max, and an 8 pitch in Black Max extra cup. It also lists a 9 pitch in Vengeance(SS) if you want to go that route.

It calculates performance with a 9 pitch as 16 mph @ 5250 rpm. Your recommended full throttle rpm range is 4500-5500 rpm.
 

jestor68

Commander
Joined
Jun 12, 2012
Messages
2,308
Re: Proper Prop for 24' pontoon

The best way to determine the optimum prop pitch is with a tachometer and adjust pitch based on the expectation that 1 inch of pitch change should result in a change of 150-200 rpm. Since your motor's rated horsepower is at 5000 rpm, you want to shoot for that as a minimum.
 
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