Considering all the force comes from a flame front backed by irregular propagation, I wonder why they use the same ICE design as automotives. I
would guess a duel-piston, a tubulence head(
Design To Improve Turbulence In Combustion Chambers), a hybrid, stirling, or even a multitude of smaller engines would be easier to install/maintain and be more efficient.
A container ship is massive and represents a relatively consistent moving mass. The cavitations and fluxuations in water current and pressure over the drive is always changing.
The maritime industry is finally figuring out that propellors work better when they have flexability, variable pitch, and better surfaces(
Whale-inspired bumps improve efficiency of ocean turbine blades) to actually conform to the water instead of spinning foam. Duh.
A drivetrain that can vary fuel requirements with the load will work better as well.
Mabye a massive crank/flywheel will, I don't know.