Fuel consumption / MPG - 17' 2.3L boat

[aJohn79]

I am preparing for a longer than my typical navigation trip in Lake Michigan. I have never measured the MPG of my boat. Can you guys with similar configuration give me an estimate. My boat is a 1990 17' Four Winns with a 2.3L OMC engine. I have the electronic ignition Pertronix upgrade. We will be traveling light, only two of us and I think my gas tank is 18 gallons. I know it will also depends on propeller and speed. My propeller is the normal 3 blade from OMC. I will try to keep engine revs in the 4,800 to 5,000 rpm range (about 30 MPH), or any better recommendations?
Thanks...

 

[QC]

Re: Fuel consumption / MPG - 17' 2.3L boat

I believe you should conservatively plan on 3 MPG. You probably get 4 . . .

If anybody posts that you're running at too high an RPM, tell them to look up the specs on that specific Ford engine

 

[aJohn79]

Re: Fuel consumption / MPG - 17' 2.3L boat

well, it ended up being about 5.5 MPG. Now, what I did not realize is that I should have not counted the last 4 gallons in the tank. While I was approaching the end of my trip the engine started runing dry as the boat was jumping up and down over the waves. I assume that the last gallons of gasoline move back and forth a lot inside the tank so the pump is sucking air for short periods of times. I know I could slow down and point the boat up so the fuel goes to the back. So, the lesson learnt is to assume a 14 gallon tank instead of an 18 gallon. Has anyone have this experience before?

 

[tommays]

Re: Fuel consumption / MPG - 17' 2.3L boat

Yes

I have a 19' with a 3.0 and 36 gallon tank which i pretend is 30 gallons

I also have a GPS with fuel flow and have found the millage is between

2MPG(rough water going slow pushing through bad chop)

And 5 MPG(dead flat no wind or current)

With a realy world AVG of around 4 MPG on trips up to 90 miles



Tommays

 

[scoutabout]

Re: Fuel consumption / MPG - 17' 2.3L boat

Airplane specs are very careful to note total fuel capacity vs total useable capacity as often you can't safely assume you are able to suck up that last couple of gallons due to tank shape, flight attitude, etc . Makes sense that the situation for boats would be very much the same.

For trips of any significant length I fill the main tank, then carry two of the five gallon plastic containers for good measure. That way I know when and if the big silence descends, I've got safe reserves.