I realize this is a game versus real-life, but seems to me like the game numbers for the characteristics of a diesel engine would be based on real-world data.
While I don't know the side of the boat's engine, I'd guess it to be in the 1200-1500HP class, which would be quite adequate for a boat this size. So a simple online search reveals:
"A 1500hp diesel engine consumes approximately 106.5 gallons (about 403 liters) of fuel per hour at full load, or about 32.2 gallons (about 122 liters) at one-quarter load. The exact consumption rate depends on factors like engine design, age, and the specific application, such as a generator or vehicle."
I'm guessing there are some "make it challenging" factors at-play for the sake of gameplay versus real-world, but it seems a bit extreme to me. I'm hoping, as the game progresses through development, the devs will do a but of tweeking to the diesel engine numbers.
As to the original point here, it would seem the whole point of "booster" and "super booster" would be about horsepower and possibly efficiency. Horsepower in a boat drive engine would directly translate to top-speed, so by the numbers given from the tests, looks like there virtually no variance between the cylinder types. Again, I'm hoping the devs might revisit these numbers as the development progresses. Perhaps the "booster" and "super booster" cylinders are "placeholders" for now until they can focus on lesser elements of the game; probably, right now, they're focused on the core issues.