Hi David,

Just to clear up a few misconceptions re: ships main engines. Most ships Main Engines are direct coupled i.e. The crankshaft is directly connected to the prop i.e. no transmission losses.

Also the current Two Stroke Diesel main engines are the most efficient by far.

I will give the specs for the Wartsila NSD (Sulzer) RTA96-C 12 Cylinder below:-
Bore: 965mm
Stroke: 2489mm
Weight: Over 2,000 tons (Crankshaft is over 300 tons)
Maximum Continuous Rating (MCR): 89,640 HP @ 100rpm
Maximum Output: 100,000 HP @ 101.5rpm
Fuel Consumption @ MCR: 0.278 lbs/HP/hour
Fuel Consumpton @ max economy: 0.26lbs/HP/hour
Thermal efficiency @ max economy: 50%+
Fuel consumption @ max efficiency 1600 gallons/hour

This power plant would drive a ship with a cargo carrying capacity of well over 200,000 tons.

For comparison, automotive and small aircraft have British Standard Fuel Consumption figures in the range of 0.40-0.60 lbs/HP/hour and a thermal efficiency of 25-30%.