A frequently asked question is how much fuel do you burn per hour or mile on a cruiser? This varies widely based on speed. A cruiser can travel as slow as a trawler and get good fuel economy or can travel at 25 kts if necessary to reach port before a storm or just make distance for any reason.
At idle speed which is 6.3 mph the fuel burn is 3.2 miles per gallon.
At 8.5 mph ( 1000 rpm ) the fuel burn is 1.8 miles per gallon .
At 15 mph ( 2,000 rpm ) the fuel burn is .82 miles per gallon.
At 26 mph (2,600 rpm ) the fuel burn is .87 miles per gallon.
The boat is just pushing water at 15 mph. There is no advantage to the hull design until the boat is on plane.
Theoretically, if the boat does the Great Loop (6,000 miles ) at idle speed the fuel cost at $4.00 per gallon would be $7,500. If the boat does the Great Loop at 26 mph the fuel cost would be $27,586.