Prop for my pontoon boat. Help please!

Silvertip

Supreme Mariner
Joined
Sep 22, 2003
Messages
28,771
Re: Prop for my pontoon boat. Help please!

Pontoons are not planing hulls in the same sense that a V-hull would be and therefore take a lot of power to move at 30 mph. It would appear the prop you have is pretty close. The best prop for any application is one that allows the engine to operate at or very near the upper end of the manufacturers WOT rpm band -- which is where you are at. Speed and fuel economy will be what it is with that prop. Installing one with higher pitch lugs the motor, requires more throttle to maintain the same speed as before and therefore sucks even more gas. And just so you know, a 150 HP engine burns about 15 gallons of fuel per hour at wide open throttle. It is a fact of life and it doesn't matter what engine you have -- that number is 10% of rated HP. Making sure the engine is properly tuned and making full power is key to optimum fuel economy. Compression check and perhaps a de-carbon process is in order.
 

steelespike

Supreme Mariner
Joined
Apr 26, 2002
Messages
19,069
Re: Prop for my pontoon boat. Help please!

Usually best practical speed is around 2000 to 3000 rpm.one test I saw a 500 rpm increase from 2500 to 3000 knocked mpg down from 4.7 to 3.5. 4.7 being the best practical cruising speed at 13 mph.Wideopen throttle was 5400 rpm 36 mph,15.69 gph 2.3 mpg.This was an Evinrude Etec similar to your motor but Direct injected.thus likely gets slightly better gph.
You might give us your rpm and speed at 500 rpm intervals.Being very careful to adjust trim and weight at each interval.Its possible prop selection could improve things very slightly.
Your rpm and speed intervals will tell a lot.Try these runs with just one or 2 aboard.
 
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