1.8 MPG - Typical?

J

JoLin

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Dangerous question, I know.

Okay, bought the boat at the end of last season and have now travelled 123 'over the ground' miles and put 66 gallons into the tank. My usage so far has been pretty typical of the way I boat all season in terms of time spent at idle/low speed and at cruise (3100-3400 rpm).

She's 27'4" LOA, 9'4" beam and weighs 9000 lbs all loaded up with Linda and I aboard. Twin 4.3's with TBI and single-prop drives.

Anyone have comparison info for a similarly sized and equipped boat?
 
Sounds about right to me with that boat and power package. I sure many of us would kill for 1.8mpg That number will vary for you a bunch depending on wind, current, and how loaded down you boat is. But like anything else, all that should average out over time.
 
Kill is the right word! Even my lightweight, small block Silverton gets only 0.8mpg during general usage.

Gerry
 
Twin 350 MPH 5.7 -

My flow scan says on an average: 3200-3400 RPM about 23-26 MPH, I am burning about 31 GPH.

But sometimes like last week with all the bottom crap before my hual, I was at 3200 RPM 19MPH and burning 34-35 GPH.

Ouch !!
 
My T/Merc 7.4 EFI motors would burn 12-14 GPH each running at 3200RPM.....consistantly.
 
JoLin is doing math based on his usage, don't confuse that with actual burn at cruise via a B&G, SmartCraft, or Floscan.

Just Saying
 
Was the tank full when you got it and is it empty now? This is a very hard number to guess at. Get a log of every trip and every fill up and you will get a idea of what you burn. No matter what you burn someone will tell you a can't be true I know this oh to well.
 
quote:
Originally posted by JimPend

Experinced boaters use GPH.

Click to expand...

That's because MPG is usually a fraction and that's just embarrassing to admit to anyone.
 
Fuel usage is very subjective. My GPH varies greatly depending on speed. The faster I go, the more fuel I use. If I take it slow and easy, I can stretch the fuel. Essentially, I can go a greater distance on a fixed amount of fuel at 5 MPH than I can on that same amount of fuel doing 30 MPH. Naturally, it will take me a lot longer to get there.
I've found that the key to optimal fuel usage is to try to avoid running around with the secondaries open on my carbs.
 
OK let me clear this up before we go astray :)

There is nothing wrong with computing your gas usage doing math, actually it is truly reflective and accurate to what you are using in fuel. My point was, that those numbers cannot be used to compare to other boats. In reality those numbers (math) are useless numbers when trying to make comparisons.

If you want to make comparisons on fuel usage, you need to quote cruise speed and burn at that speed. You need to quote such base on a fuel flow monitor or such a device like smart craft or that old B&G thing.
 
quote:
Originally posted by walterv

OK let me clear this up before we go astray :)

There is nothing wrong with computing your gas usage doing math, actually it is truly reflective and accurate to what you are using in fuel. My point was, that those numbers cannot be used to compare to other boats. In reality those numbers (math) are useless numbers when trying to make comparisons.

If you want to make comparisons on fuel usage, you need to quote cruise speed and burn at that speed. You need to quote such base on a fuel flow monitor or such a device like smart craft or that old B&G thing.

Click to expand...


Fair enough- I don't have a flo-scan, so can't compute GPH at a given speed. I'll accpet that it wasn't a good question to ask or a good way to ask it.

(yes, the tank was full when I started logging miles. It took 66 gallons to refill it after 123 GPS miles.)
 
"(yes, the tank was full when I started logging miles. It took 66 gallons to refill it after 123 GPS miles.)"

Then all else aside I'd say you are doing great. If you care to try to calculate any numbers then just keep a loop of running hours Miles and fuel burn and do the math in every way MPH GPH this could become helpful to spot a problem do the road, if these numbers start to change you should pick up on it.
 
Our Sea Ray 270 got about 1.8. Our Sea Ray 340 gets about .8 at 27 mph cruise. At "cocktail speed" 7mph we get about 1.6. The good news is we do not have to drive it to work every day.
 
Okay, I confess I don't get this. It would seem to me GPH is the number that can't be compared since it does not take into account speed or distance. But MPG at cruise would seem a fair comparison of boat fuel efficiency accross all kinds of boats from go-fasts to trawlers. Ie... who goes farther on a tank of gas.

Case in point, in looking at fuel burn numbers for some Fountain go-fasts, GPH was sky high... like 50-60gph for a 38ft boat. But their MPG at cruise was actually pretty good because they go so damm fast.

I get Walters point about averaging using Math, JoLin is getting his MPG accross all kinds of speeds and conditions. But in general why would GPH be any better than MPG?
 
Most all comparisons are done using average cruising speed under good to fair sea conditions with a minimally loaded boat etc etc etc. I have been looking at the boat test videos / write-ups for years. So according to my boat specifications, at 3400 RPM at 28 MPH it should get 179 miles with my 200 Gallon tank. Yea Right !! I have not had a trip like that to run at 28 for a 179 miles straight prove it one way or another.

I agree with Walter you can't really judge using flow scans, I just happen to have one. Lately I just keep the cover on it because I know I am burning less than a gallon per mile of travel at a reasonable cruising speed. GPH or MPG we are all spending too much.

Many years ago boating was a rich man's hobby, then it became reasonable for everyone or at least many more than before. Now it is getting to be very expensive. But we all know that, but the passion keeps us going. I should name my next boat "Fund Mover" or "Rob Peter / Pay Paul"
 
quote:
Many years ago boating was a rich man's hobby, then it became reasonable for everyone or at least many more than before. Now it is getting to be very expensive. But we all know that, but the passion keeps us going. I should name my next boat "Fund Mover" or "Rob Peter / Pay Paul"

Click to expand...


Admittedly I never paid much attention until recently, and not because I'm rich!

First boat was 21' cuddy with a 175 outboard. I didn't really care, I was learning to 'drive a boat'. I had a lot more to worry about than fuel usage.

When I upsized to a 24' pocket cruiser with 5.7 I/O, I was pleasantly surprised that I didn't seem to be using any more fuel than I did with the previous boat, so again, it didn't really matter.

With the 'new' boat, twin engines and gas at well over $4/gal, I got interested :-)

Interesting answers and food for thought, as always. Thanks.
 
GPH is great if you are looking to go for a cruise, but when getting from point A to point B, I would rather use MPG (or GPM_ Gallons Per Mile). With my GPS i can show either one or both.
 
No matter how you measure it, 1.8 MPG with twin 4.3's is not typical. It's fantastic.

Bob
 
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