Fuel Consumption - Is This Right?

IDFISHER

Petty Officer 2nd Class
Joined
May 11, 2017
Messages
158
I did a fuel consumption calculation yesterday and I I came up with approximately 4 Miles/gal at WOT. Does that seem right?
- 1994 60 HP Johnson
- 16ft Starcraft SS
- 2 Adults, 2 batteries, 8 HP kicker motor, 9 gallons of fuel.

Motor runs perfect, gets on plane fast, runs about 30 MPH at WOT. Just curious if that's normal consumption. Thanks!
 

Crosbyman

Vice Admiral
Joined
Nov 5, 2006
Messages
5,427
sounds approx. ok for me ...

my Merc Classic 50 from the 80s would go about same distance on a 5 gal tank.
expensive critters these days at 8$ gal in Canada

time to move up to fuel injection technology my 75 ETEC burns half my Merc 500 would and trolls at about 2 cups (.6L hour ) :)


but for the price of a new motor you can go a long way..... if you only ride your 60 hp for 50hours/summer
 

dwco5051

Commander
Joined
Sep 14, 2008
Messages
2,405
There is an old rule of thumb that mpg at full throttle is equal to 10% of motor horsepower. In you case 6 mpg. Those older OMC's were known as fuel hogs so depending on many things including loading, prop, engine age and on and on you are probably in the ballpark at 4. What is the max HP you hull is rated for?
 

IDFISHER

Petty Officer 2nd Class
Joined
May 11, 2017
Messages
158
sounds approx. ok for me ...

my Merc Classic 50 from the 80s would go about same distance on a 5 gal tank.
expensive critters these days at 8$ gal in Canada

time to move up to fuel injection technology my 75 ETEC burns half my Merc 500 would and trolls at about 2 cups (.6L hour ) :)


but for the price of a new motor you can go a long way..... if you only ride your 60 hp for 50hours/summer
My brother in law has new 60 HP mercury on the same size boat that i have and we went probably 35-40 miles on 3 gallons. New technology is certainly impressive.
 

Scott Danforth

Grumpy Vintage Moderator still playing with boats
Staff member
Joined
Jul 23, 2011
Messages
49,460
I did a fuel consumption calculation yesterday and I I came up with approximately 4 Miles/gal at WOT. Does that seem right?
- 1994 60 HP Johnson
- 16ft Starcraft SS
- 2 Adults, 2 batteries, 8 HP kicker motor, 9 gallons of fuel.

Motor runs perfect, gets on plane fast, runs about 30 MPH at WOT. Just curious if that's normal consumption. Thanks!
BSFC for an outboard is about 0.5 # of fuel per HP per hour for steady state loading (your motor may be different) 2-strokes are closer to 0.55-0.8 depending on design lets pic 0.6 for your 2-stroke

if you run for 1 hour, 60 x .6 = 36 # of fuel, or at 6.82# per gallon, you would have burned 5.3 gallons of fuel in that hour. to burn 9 gallons means you were shy of 2 hours at WOT

There is an old rule of thumb that mpg at full throttle is equal to 10% of motor horsepower. In you case 6 mpg.
that would make a 1000hp motor have 100mpg. the old rule of thumb is flawed unless you mean that the 10% of the HP rating is the amount of fuel burned in gallons. then that is about right
 

dwco5051

Commander
Joined
Sep 14, 2008
Messages
2,405
There is an old rule of thumb that mpg at full throttle is equal to 10% of motor horsepower. In you case 6 mpg. Those older OMC's were known as fuel hogs so depending on many things including loading, prop, engine age and on and on you are probably in the ballpark at 4. What is the max HP you hull is rated for?
My mistake: Change mpg to fuel burn rate . My brain got ahead of my fingers when typing this . Thanks Scott, missed that when I first proof read it. Another senior moment.
 

jimmbo

Supreme Mariner
Joined
May 24, 2004
Messages
13,442
sounds approx. ok for me ...

my Merc Classic 50 from the 80s would go about same distance on a 5 gal tank.
expensive critters these days at 8$ gal in Canada

time to move up to fuel injection technology my 75 ETEC burns half my Merc 500 would and trolls at about 2 cups (.6L hour ) :)


but for the price of a new motor you can go a long way..... if you only ride your 60 hp for 50hours/summer
I doubt I will be doing any Boating this summer because of the Robber Oil Barons. Time to Nationalize(turn into a Crown Corporation) 1/2 of this Industry, as it is Too Important to leave it in the hands Private Companies
 
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