Gallons per Hour

[Baker]

OCDiver says 1 gallon per 20 hp. Hmmm, I have to question that. Sounds way high. That would put my 36 TT with 120 F.L. at 6 gls per hour. I don't burn half that. In fact I burn between 2 and 3 per hour.

People sometimes look at me funny when I can't quote a litany of GPHs and MPGs or GPMs.
Seriously, who cares. A heavy season of cruising requires me to buy a few hundred gallons of diesel. A season filled with other commitments just saw me top off the tanks at the end of the season for storage.

The first few years I owned the boat I was very concerned that my fuel was getting old. I had spent a lot of time doing other projects than cruising.

pete

I think you missed the point. It doesn’t mean your engines are developing 120hp ALL THE TIME!!! His point was if your 120hp Lehman’s are running at 50% then they are burning 3gph.

 

[Nomad Willy]

Codger ll wrote;
“My max rpm is 3300 but I never push her that hard. (That would give me 22 knots”

HaHa ... You may like 22 knots. But you should do that once for several minutes every 2-3 months IMO. You won’t cause a bit of harm providing that’s your rated rpm.
Right after I bought Willy I ran her to the pin in a rather narrow channel. Found out the engine was overpropped. And then the engine quit. Got it going before we anchored. Was a fuel delivery problem. A problem like that rearing it’s head when you’re way out somewhere could be big trouble or dangerous. Just say’in......

 

[markpierce]

Sweet spot at 1800 rpm with 6.3 knots using 1.7 gph:

 

[OldDan1943]

Sweet spot at 1800 rpm with 6.3 knots using 1.7 gph:

Now that is a mighty fine bow wake

 

[TWille]

Gph

Guess i need to get the graph paper out, a fixed course, a fuel dock, and a few different types of preferred beverages to have in hand while doing the calculations after we get docked. On several different days at several different speeds - maybe stop at end of day one with the beverages.

 

[Beaverlake]

I discovered a simple fuel burn correlation. Annual fuel burn is directly proportional to enjoyment. More fuel = more fun. (We Cruise at a nominal 7.5 knots with the occasional run up for the benefit of the turbos). Of all our annual boat related expenses fuel may not be the least, but it’s not near the top either. Taxes/fees/insurance, moorage, things that go bump on a 20 year old boat, etc are all up there.

That noted, with a cruise loaded boat, averaging PacNW current push/pull, 1450 rpm x twin Cummins 330s, the occasional high speed run, and generous generator time we’re averaging 5-5.5 gph total consumption. We’ve had as low as 4.5 (I did some great route planning and timing) and as high as 8+ (needed to run quickly across the Straits of Georgia along the way).