I've cruised and circumnavigated with two diesel tanks
of 100 litres each (44 Imperial gallons; 51 US gallons total) plus half a dozen twenty litre jerry cans and have genwrally found that to be sufficient.
My sailboat has a 38 horsepower diesel and is 42 feet in length of a moderate displacement
design. You probably onowthe general rule
of thumb that "a diesel engine
consumes (about) a tenth of a litre per horsepower generated per hour" which I have found over all conditions over a number of years to be true.
Please bear in mind that a 38 horsepower engine will not chew through 3.8 litres per hour if you are only running it at say, half revs. Each engine has a power curve and fuel consumption
curve. I have a Nanni diesel with top revs of about 3300, and usually motor
along at between 1800 to 2000 revs - a lesser horsepiwer output. It'll use more fuel at top revs.
Hope this helps
N.Z. Yacht Herodotus
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