>Al,
>
>>I'm assuming you're measuring efficiency as energy used per tonne-kilometer of goods moved. Ships are very good.
>
>Not really. The diesel fuel is burned (loss #0 because the fuel isn't 100% oxidized) in a piston based engine (loss #1 primarily frictional losses) which drives an electrical generator (loss #2 you can't convert mechanical energy to elecrical energy at a 100% rate) which powers an electrical motor (loss #3 you can't convert elecrical energy to mechanical energy at a 100% rate) which spins a prop (loss #4 frictional loss) which causes water displacement without 100% efficiency (loss #5 frictional loss).
>
>A jet engine burns the fuel (loss #0 because the fuel isn't 100% oxidized) which drives a turbine (loss #1 this energy is intentionally extracted to drive the compressor on the shaft to compress the incoming air).
>
>>As for jets - if they were so efficient, we'd be shipping grain and coal by jet ;)
>
>Fuel efficiency is only one factor, and for most of the stuff transported by ship and rail there aren't other viable options.

Let's compare a modern, fuel-efficient commercial airliner to a ship.

Airliner: Boeing 777-200LR

Ship: 200,000 metric ton cargo capacity ("payload"), powered as per Neil's specs

B777: from http://www.boeing.com/assocproducts/aircompat/acaps/777rsec3.pdf Fig. 3.2.1 this aircraft can carry 209,105kg payload a distance of 7,500 nautical miles. Maximum fuel capacity ( http://www.boeing.com/commercial/777family/777technical.html ) is 171,160 litres. Assuming that maximum range means a 10% fuel reserve then fuel consumed for this journey is 0.9 x 171,160 = 154,000 litres.

So, kg-nm per litre of fuel is (209,105 * 7,500) / 154,000 = 10,184.

Ship: assume efficient cruise of 20 knots (nautical miles per hour). To travel 7,500 nautical miles would require 375 hours. Its engine burns 1,600 gallons per hour (assume imperial gallons @ 4.54 litres/gallon), which is 7,264 litres per hour. Total fuel consumption for a 7,500 nautical mile journey would be 375 * 7,264 = 2,724,000 litres.

So, kg-nm per litre of fuel is (200,000,000 * 7,500) / 2,724,000 = 550,660.

To travel the same distance, a bulk carrier burns about 20x the fuel of a jet but carries about 1,000x the payload. The ship appears to be about 50x more efficient than the jet. These are real-world figures, not theoretical.