gryffron wrote:dspp wrote:You are confusing a "cruise" liner with a fast passenger liner.
I'm using typical figures that were easily available for a modern (and hopefully quite efficient) passenger ship.
I fully concede cruise liners have theatres and casinos and comforts and lots of staff and various other non-essential passenger spaces. But the slower you go, the more recreation you're going to have to provide. By your own figures, even your proposed slow cattle boat is no more fuel efficient than an all-tourist-class modern aircraft. So the conclusion is the same: Moving passengers from aircraft to ships doesn't help solve the emissions problem.
I'm sorry but the fuel consumption is directly related to the speed, and not in a proportional way. In just the same way as flying Concorde to NY at Mach 2 will use up a lot more fuel than flying a 747 to New York at Mach 0.9, so too will motoring a ship to New York at 34-knots consume a lot more fuel than motoring the same ship at 15-knots:
Look at the fuel curves for the 32,000 tonne vessel and you will see that at 15-knots you will burn 35 tons/day, and at 15-knots it will take 10.1 days, so 350 tons. Divide 2500 passengers into that and you get 0.14 tons fuel per passenger per crossing.
QUEEN MARY in LUXURY FAST LINER SERVICE = 0.75 tons @ 4.5-days
LARGE PLANE = 0.25 tons @ 0.5-days
ECONOMIC LINER = 0.14 tons @ 10-days
The selections of speed are matters of choice, not compulsion.