fuel consumption

Read Charlie Wings book, the livaboard report.
In it, he poled people on their fuel consumption. His graph shows that boats ranging from 30' to 42' got at least 8 NMPG or more. That seems high compared to other bits of info I've seen.
I'm curious as to what people with 40' to 45' sailboats with a moderately sized deisel engine are getting for fuel consumption.
Thanks

[Paul L]

It sounds low to me, although I'm not sure what conditions he is discussing. A boat that size probably uses somewhere between .5 gal and 1 gal per hour. running at just under hull speeds in light conditons. With their hull speed for the smaller boat at around 6kts, you would get 6 / .5 = 12 miles per gal.. For the middle sized boat you might get something like 7.5 / .75 = 10 mpg. And a bigger boat might be 8.5 /1 = 8.5 MPG.

[delmarrey]

At 6.5 to 7 Knots (hull speed, no current-40' boat) with a 50 hp Diesel and a folding prop, it burns 2 gal. hour, on the average, with a 30 gal. tank.

[Catamount]

What are your other bits of info? Perhaps they relate to power boats rather than sail boats? Michael Brower and Warren Leon, in their 1999 book, The Consumer's Guide to Effective Environmental Choices, cite some values (page 110):

"A typical 17-foot powerboat will use more than twice as much gasoline as an average car going sixty miles per hour. Large luxury boats use gasoline even more extravagantly and can require two or more gallons to travel just a mile. Just ten hours of luxury boat cruising at a hundred gallons an hour is equivalent to more than a year's worth of driving an average car, and it sends twenty thousand pounds of carbon dioxide into the atmosphere. Boating expert Andre Mele asks 'Is ther any form of transportation more profligate?' He concludes, 'Only a fighter jet consuming over 600 gallons during half an hour of supersonic combat flying, might get worse mileage [per passenger] than a large pleasure boat.' " (Brower and Leon are citing from Andre Mele, 1993, Polluting for Pleasure, WW Norton & Co, New York.)

Two or three gallons per mile for large power boats was confirmed for me by one of my students who used to crew on a large sportfishing charter boat operating off Cape Cod, Massachusetts.

But sailboats generally don't use anywhere near this much fuel when operating under power. For obvious reasons sailboat hulls tend to be relatively efficient as displacement hull forms. They also are travelling more slowly, even under power. Thus they tend to have smaller, more fuel efficient engines than equivalently sized power boats. Power boats may have efficient planing hull forms, but need a lot of power to get up on plane (and thus use a lot of fuel).

For their latest boat, the Dashew's were contemplating a trawler, but ended up building a power boat based on a sailboat hull form, because it was so much more efficient. See: http://www.setsail.com/s_logs/dashew/dashew214.html

I have not measured the fuel consumption of my boat yet, but I expect to get about 15 nm per gallon (10,000 lb displacement, 15 hp 2-cylinder diesel, 28'3" waterline length, estimating 1/3 of a gallon per hour motoring at 5 knots...)

Regards,

Tim

[Jon D]

Real world on the Moody at cruise ~ 7.25 knots or so we burn 1.25 to 1.5 gal/hr on a Perkins 4.236 [85 HP] driving a 19" three blade max prop.

[Pblais]

Perkins Perama 35 hp - 16 inch 3 blade is .75 gal / hour @ 2000 rpm. Your hull speed is of course your own. On flat water that would be 8 nm/US gallon for me. On my 33 ft boats that carries a lot more beam than most. Your hull speed is perhaps the bigger component. I would consider mine to be the low side of median.

[GordMay]

Del:
I’m confused!
3.25 nm/gal (6.5 Kts ÷ 2 Gal) seems pretty hungry for a displacement boat at a reasonably conservative hull speed.

The more efficient displacement boats require between 1 and 2 HP per ton to attain hull speed.
Is your “40 footer” between 25 & 50 Tons displacement?

Gord

[Vasco]

Yanmar 4JH3E, 56 hp, 39'03"LOA, 35'01"LWL running at 6 - 6.5 kts. 3/4 gal per hour. About 18,500 lbs. displacement with all the junk I have aboard.

[delmarrey]

Thanks for catching that Gord!

That was 2 hours per gallon! NOT 2 gallons per hour.

So, I guess I better make that .5 gallon per hour.

I can put 60 hours on a 30 gallon tank running at around 3200 rpm's

It's a Pathfinder (VW) motor and it weighs in at around 8 tons depending on supplies.

[irwinsailor]

Our boat uses 2 gallons per hour running at 2500 RPM at 7.5 knots. We have a 90 hp Westerbeke.

[Alan Wheeler]

Just remember everyone, that there is US Gallons and UK Gallons. Just to mess it all up more, my boat uses about 8-10ltrs/hr. But that is in economy cruise mode. If I want that extra 1.5knts, I can double that consumption figure.
What I would like to know, how much fuel do you all carry???

[GordMay]

“Southbound” (C&C29' c/w 13HP 2GMF) has a 20 Gallon Fuel Tank, augmented by 24-30 Gallons on deck (44-50 Gal total). Burning 0.5 Gal/Hr @ 4-6 Kts, we had a theoretical range, under power, of between 350 - 600 nm. In actuality, I’d guess that as much as half the fuel was burnt at anchor, or maneuvering (Bahamas).
Cruising Lake Superior, we didn’t carry any deck fuel, and seldom filled our water tanks.
Gord

[Euro Cruiser]

"I'm curious as to what people with 40' to 45' sailboats with a moderately sized deisel engine are getting for fuel consumption."

As Jon and Delmarey indicate, depending on the type of boat and the % of hull speed one motors at, the answer could be in the 1.5-2 gph range. What's not being mentioned and IME is most influential to the fuel consumption which cruising yachts get are a) availability of fuel, and b) its price. E.g. in Europe fuel is conveniently available but runs about $6 USD/gal (> 1E/liter), except the UK. In many parts of the Pacific, fuel is infrequently available and a logistics challenge to ferry to the boat. Along the USA's East Coast in our inland waterway - where virtually every transiting boat mostly powers - an owner will move the boat more quickly and burn more fuel than in the above environments, at a fuel cost that is half as high.

FWIW we've averaged .9 gph at 6-6.5 kts (equivalent to approx. 7 NM/gal) in our 11 ton/13M/42' ketch over the last 3 years while in Europe, according to a fuel log I've kept. If we bumped up our speed to a steady 7 kts, fuel burn would almost double.

Jack

[Talbot]

It's a Pathfinder (VW) motor and it weighs in at around 8 tons

Delmarrey, thats a darn heavy engine!



My fuel consumption is totally dependent on wind speed. If looking at low wind then 6 kts = 3/4 gallon (UK)

[Alan Wheeler]

Euro, I should have added, my boat is 45ft and comes in at 26T. I have a Perkins 6-354 engine. I am carrying 360Ltrs of fuel. Our fuel cost at present is NZ$1.06/ltr at the fuel warf. It's NZ$1.02/ltr at the city fuel stations.
I need to increase my fuel holding for big trips, but I think I may do that with carrying additional 20ltr containers instead of another fuel tank.