Bah, not that it matters in the least.
" really what you want is some measure of the surface area of the object."
A container ship does about 24knots = 40feet/second
It uses around 350tons of fuel/day = 4.5 l/s = 1.2USgall/s
So it does a very similar consumption - around 35feet/gallon
While carrying 150,000tons of cargo = 320million pounds.
http://en.wikipedia.org/wiki/W%C3%A4rtsil%C3%A4-Sulzer_RTA96...
The steam turbine has until recently been the first choice for very large power main propulsion units. Its advantages of little or no vibration, low weight, minimum space requirements and low maintenance costs are considerable. In steam turbines high pressure steam is directed into a series of blades or vanes attached to a shaft, causing it to rotate. This rotary motion is transferred to the propeller shaft by gears. Steam is produced by boiling water in a boiler, which is fired by oil. Recent developments in steam turbines which have reduced fuel consumption and raised power output have made them more attractive as an alternative to diesel power in ships. They are 50 per cent lighter and on very large tankers some of the steam can be used to drive the large cargo oil pumps. Turbines are often used in container ships, which travel at high speeds.