Time for the U.S. Merchant Marine to chime in.
When I started sailing the Ford fleet had two ships, the Benson Ford, 1920, and the Henry Ford11.1924.
Each were fitted out with a Junkers Opposed Piston Engine of 4,000 Horsepower, and burned 100 GPH to pu***he ships carrying 12,500 toms at 10 knots.
The current “Oueen of the Lakes” has 4 fairbanks morse engins developing over 16,000 horsepower and uses 650 Gallons Per Hour to push 65,000 tons down the lakes.
So fuel economy is inproving but them damn high speed diesels are nervewracking. (noisy)
Those old Junkers were at least quiet.
Kurt