50 hp outboard mpg?

[iceranger792]

I have a 15 ft boat and a 50 hp motor. I took it out for the first time today and burned through the gas pretty quick. I'm lookin for some info on what the mpg is on a 50 hp with 3 guys

[walleyewild]

What size gas tank?

2 or 4 stroke?

Year?

With most motors it is gallons per hour.

I had a 40hp merc 2 stroke on a 16' Lund with a 6 gal tank that I could run about 10 to 15 miles before I would have to fuel up again.

Every motor is different for fuel economy.

WW

[PerchJerker]

Your throttle / rpms are everything.

I have a gauge that tells me my fuel consumption so I know exactly how my boat is running. My motor is a 175 so maybe not too comparable to a 50, but you'll see what the throttle / rpms does to fuel consumption.

When I run WOT I'm going 5700 rpms and 50 mph and burning 17 gph (geting just under 3 mpg).

If I throttle back to a cruising speed of 30-35 mph I run about 4000 rpms and about 7 gph, so now I'm getting 4-5 mpg.

Another way to look at it is the range I get for a tank of gas .... at WOT I'll get about 100 miles out of a tank of gas .... at 4000 rpms I'll get about 175 miles out of a tank of gas.

To get your best gas mileage, get your boat on plane and then back down on the throttle --- keep your boat on plane, but don't drive faster than you need to --- and you'll get a lot more mileage out of your gas.

[CRAZYEYES]

Theres a lot of variables to mpg or gph. On either of my engines it varies a lot depending on the # of people, wind, weight. One of the biggest things that you can do is make sure that you are running the right prop. You might scoff at paying 100-200 $ for a prop but with 3$ gas they can pay for themselves and you'll be happier with performance.

[boatfixer]

You can figure approximatly 10% of you horsepower per hour at WOT.

10% of 50 is 5 gallons per hour at WOT

Not scientific but its close.

[BoxMN]

Hey boatfixer, that is great info to have, even if not exact. Thanks!

I think from reading old Bass and Walleye Boat mag over the years, it always seemed that the best mileage from about all HP ranges was when running right around 3000 rpms, give or take. I think we cruise at about 3100 rpm with our 150efi when we want to use the least gas. And about 5450 when we want bugs in our teeth

[Tom7227]

Iceranger,

When you were at low throttle did you see any film of gas on the water surface? A few years ago my old rig was eating gas like there was no tomorrow and I found out that the carburation was boogered up. Stuck float or something, I can't remember. A trip to the shop was required and things smoothed out pretty well after that. Could be part of your problem.

Tom

[muddpuppy]

I have a 16 boat 2stroke 50hp Yamaha 12 gal gas tank. loaded with 2 people Running the rivers I get 50-60 mile to the full tank running fumes thats at wot most of the time so about 5.5 MPG

[solbes]

Just checked out my F75 a couple of weeks ago after getting the Fuel Flow displayed on my F75. I saw readings close to 8 mpg at 3400 RPM's, pretty good in my book. Dropped just below 5 mpg at WOT @ 6000.

Boatfixer's formula would suggest 5.2 mpg (39 mph / 7.5 gph). You rock! Opened my eyes to see that I use 35% less fuel by running on a cruising plane instead of WOT.