Gallons of deisel fuel per hour

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Gallons of deisel fuel per hour

Postby Connie Brooks » Mon Feb 20, 2017 4:29 pm

We will be buying a 1986 42' Classic with two 120 hp Lehman engines. Could we please get some feedback about the average gallons per hour fuel consumption when cruising at an average 8 knots. Thank you.
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Postby GB42-267 » Mon Feb 20, 2017 7:05 pm

Depending on how heavily loaded your boat are with gear and supplies, the weather and current condition, etc. Between 4.5 - 5 gal/hr. is in the ball park.
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Postby Connie Brooks » Tue Feb 21, 2017 10:27 am

Wow. 4.5 - 5 GPH is more than we were hoping for. Does that seem correct to other 42' classic owners? Maybe we should cruise at a slower speed. Thank you for your response. It is much appreciated and needed.
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Postby Don Prior » Tue Feb 21, 2017 10:43 am

Over the last few years I have totaled the engine hours and the amount of fuel used for each year.

The average is 4.5 gallons per hour but that includes the furnace and the generator (very few hours on generator)

I cruise at 1750 RPM which in calm water is 8 to 8.5 knots.

I find this consumption to be normal and also one of the lower costs of running a GB42.

Fair winds.

Don
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Anacortes, Wa.
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Postby Connie Brooks » Tue Feb 21, 2017 11:00 am

Don, Thank you for your response. Please tell us about your furnace. We plain to cruise Maine and a bit more north, so we were thinking about various ways to heat the boat.
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Postby Don Prior » Tue Feb 21, 2017 12:07 pm

Connie

Brassbounder has a relatively new Wabasto DBW 2010, 45,000 btu marine diesel hydronic furnace.

I have it set up with three zones; the forward cabin, aft cabin and salon. There are outlets in each head as well but they are controlled by the cabin thermostats.

For our North West winter cruising this is more than enough heater. I am not sure how it would do in Maine but it is great for Washington and BC.

The furnace uses less than a liter per hour of burning time and very little electrical power. I leave it on when I anchor with no problems.

Maintenance is minimal with a cleaning every spring and fall and a new injector nozzle every two years.

I am very happy with it.

Fair winds.

Don
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GB 42-139
Anacortes. Wa.
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Postby Connie Brooks » Wed Feb 22, 2017 4:55 pm

Don, Thank you for the furnace info. We'll look into it.
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Postby Marin Faure » Thu Feb 23, 2017 2:05 pm

We have a GB36, so a lighter boat than a GB42. We run our two FL120s at 1650 rpm at cruise which gives us about 8 knots. Our props are 4-blade, 23" in diameter with a 16" pitch. At 1650 rpm the fuel consumption of both engines together is about 5 gph.
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Postby FrugalWife » Thu Feb 23, 2017 6:37 pm

Hi Connie,
Since you are just buying the boat have you asked the broker to get some fuel consumption info from the seller? Most boat owners keep this kind of data. 5gph seems pretty reasonable for a twin screw 42. My single screw 36 burns average 2.25 gph @ 8 kts.
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Postby GB42-267 » Thu Feb 23, 2017 8:22 pm

Considering the relative low fuel consumption of these engines, it will be one of the lowest cost item of boat ownership. Most. Boaters put in an average of between 100-150 hours/year of running time. Some years even less for us still working for a living. The rest of the time is spent sitting at the dock. If the cruising style consist of hopping from one marina to another, marina moorage alone adds up to far more than the fuel cost. Then it is regular moorage for the rest of the year, insurance, haulout and regular maintenance. The fuel cost will now be of minor concern.
If 5 gal/hrs is considered high, I suggest to narrow the search down to a single engine or a sailboat.
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