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Old 01-14-2019, 06:32 AM   #13
catalinajack
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City: Edgewater, MD
Country: USA
Vessel Name: Catalina Jack
Vessel Model: Defever 44
Join Date: Nov 2011
Posts: 722
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Quote:
Originally Posted by Gabe n Em View Post
Thanks Al, it does go up quickly from there. I haven't crunched the numbers but as soon as you try to go above 8 kts, over 1600 rpm, the gph seems to go through the roof.
Ordinarily, I do not like it when folks respond to posts who do not have on-point experience but, in this case, my experiennce may be of some value. I have twin Lehman 120s in my DeFever 44. Lehmans are almost a 1:1 comparison to Perkins. My boat weighs 56,000 pounds with a full load-out of fuel (720 gal) and water (350 gal). We are presently doing the Loop and have logged over 4,000 miles so far. We have averaged 3.7 GPH at 1,650 RPM which yields 8.5 MPH in flat conditions, including a modest amount of generator time.

Some of the responses mention boat weight which, I think, has a direct correlation to fuel consumption. Engine model, hull shape, running RPM all are variables affecting fuel consumption but weight being moved also must be considrred when evaluating and comparing. Moving a 36,000 pound 36-foot Grand Banks equipped with twins through the water will not consume as much fuel as my DeFever weighing 50% more equipped with the same engines.
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