fuel Consumption Formula ?

Discussion in 'Outboard Maintenance' started by noeettica, Dec 6, 2010.

  1. noeettica

    noeettica Well-Known Member

    This was posted "elsewhere"

    At wide open throttle an outboard will burn 1 Gph +/- 10% for every 10 horsepower

    Does this make Sense ? for 2 and 4 Strokes ?
  2. Brett

    Brett > PRO STAFF <


  3. Frank_Sebastian

    Frank_Sebastian Well-Known Member

    This is conjecture and for discussion only. Assume you have a flat bottom boat with 700 lbs load and a 20 HP engine. At 3 mph you will get about 14 mpg. At 6 mph about 12 mpg - at 9 mph about 2.5 mpg - at 12 mph the mpg will increase to 10 mpg - at 15 mph it will drop to 8.5 mpg - and at 21 mph it will drop to 2.5 mpg again. I wish I could graph this as it would make a lot more sense, but the whole idea is your boat will be more efficient at hull speed and below. It will be least efficient as it climbs the bow wave or runs at max speed.

  4. cal1320

    cal1320 Well-Known Member

    A properly tuned 4 stroke internal combustion engine will burn about .5 lbs of fuel per hp, per hr at WOT.
    Example 15hp x .5 = 7.5lbs fuel per hr at WOT
  5. noeettica

    noeettica Well-Known Member

    so best case a 150 hp will burn 75 pounds multiply that times 6 hrs ....

    leave the egrets and Yellow fins at home !
  6. Brett

    Brett > PRO STAFF <

    75 lbs / 6.2 lbs per gallon = 12 gallons

    Egret 16 has a 41 gallon fuel tank,
    at 55 mph that gives you a range of about 190 miles
    Throttle back to cruising speed and you'll probably get 250 mile range.

    I don't see a problem Dave... ;)
  7. noeettica

    noeettica Well-Known Member

    Probably be OK if you had a couple of passengers Kicking in

    But I guess if you have a 30 K boat $120.00 In fuel should not be an issue LOL

    I'm just used to running the smaller boat / Motor Usually 3 Gallons in the Gheenoe for a 2.5 Hr run ...

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