Best fuel consumption

[Mwerks]

I have a 2008 Smoker craft 18 foot pro mag. I have been using an 14.5 X 18 prop which runs WOT at 5500 with speed a 42 mph. I have a second prop that is 14 X 19 and runs at 5300 and 44.5 mph. Both are 4 blade. Which on is best for fuel mileage?

 

[roscoe]

Maybe number 2, but both would be much better at about 3800 rpm.
And even better would likely be about 5 mph over planing speed.
Then, the first one would be better if you do a lot of short hops, starting out and getting on plane repeatedly.

So how you use the boat will affect the mpg more than switching between those two props.
JMHO.

 

[Scott06]

Dont think youll see any appreciable difference between these, but best fuel economy is typically just after you get on plane so likely the one with the lower planing speed /rpm

 

[dingbat]

Been running fuel monitoring for years.

Installed one after hearing about how great they are for adjusting trim, correct rpm, planing speed…. etc.

In reality not much help, if at all. Most changes in the above results in changes in the second decimal place.

Unless your boating in a 1 acre boat, conditions is the biggest factor on fuel efficiency, period.

“Right above planing speed” don’t mean squat if you don’t have the power or momentum to make tangible forward progress against the waves.

When all is said and done, reducing prop slip is the easiest way to increase fuel mileage. Going from 18% to 9% slip reduces fuel consumption by 9%

 

[Scott Danforth]

I have a 2008 Smoker craft 18 foot pro mag. I have been using an 14.5 X 18 prop which runs WOT at 5500 with speed a 42 mph. I have a second prop that is 14 X 19 and runs at 5300 and 44.5 mph. Both are 4 blade. Which on is best for fuel mileage?

without a fuel flow meter, we are all guessing.

as dingbat pointed out, minimal effect can be gained

fuel economy in a boat is literally an oxymoron.

since the load, weight, balance, throttle position, trim, RPM, wind, current, etc all impact fuel consumption, you are trying to hit a moving target while riding a horse at full gallop and the target is on a pogo stick mounted on an innertube in 4 foot waves

enjoy the boat, ignore the fuel consumption.

 

[QBhoy]

I used to think that just above planing speed and the more pitch and lower rpm (within the rpm range) at top end…was always meaning that prop is best for efficiency. I’d think I was so wrong to think that way, but easy to do so. Often a prop of a lower pitch can be more efficient at cruising speed (despite a little more rpm) and believe it or not…a lower pitch can often sho more top end than an inch or two more too. Depending on so many variants, it could frazzle your mind !!