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Cross The Atlantic Ocean In 3 Days - By Ship
Mr. Anonymous writes: "I keep wondering where do they find such stuff. ZZZ online is updated again, with issue #69. They write about FastShip - a 250 meters long water jet ship able to cross the Atlantic Ocean in 3 days. Speedy beast :-) It can also carry 10,000 tons of cargo." Note that this should all be couched in hypotheticals -- but I'd sure prefer to travel to Europe one day by boat than plane, and 2003 isn't that far from now.
No, not in terms of energy efficiency. If you have a displacement hull that is not travelling faster than it's hull speed (a theoretical maximum speed for a hull that is not planing, directly related to the waterline length) then the hull is effectively riding its own wave, and there is very little drag at all. If you carry a lot of wait through the air you have to use a lot of energy just to keep that weight up in the air. With a boat the displaced water supports that weight, and you only have to use energy to move that mass horizontally.
Never trust a man in a blue trench coat, Never drive a car when you're dead
I think that you got that wrong; a ship at hull speed is not riding it's own wave, it is sailing up it's own wave. Ships require a lot of power at hull speed because of this. Once they get over the hull speed (planing) the power requirement drops a bit but is still relatively high to that of a displacement type hull.
For displacement at low Froude numbers (dimensionless parameter: Fn=V^2/(g*L)) the power requirement is roughly proportional to the square of the velocity. At higher Froude numbers the effect of the ship sailing up it's own wave becomes greater and the power requirement becomes a lot higher. typically ships will have it's highest resistance when approaching hull speed...
Transportation by ship is much more efficient at low Froude numbers. Fast ships are relatively inefficient (Have you ever noticed the gas consumption for an outboard engine on a typical speed-boat ?). A good example of a displacement ship that often sails at near hull speed is a tug boat when it is not tugging anything; it has massive amounts of installed horsepower but a very short waterline length.
Seems that a boat with multiple high-power turbines moving a 750' hull at 50mph would make a hell of a racket. Has anyone considered the amount of damage this noise level would do to ambient marine life (particularly large marine mammals)? Would any environmentally-conscious nation allow this to operate in its waters? It seems like this design might make most of the crossing in a short time, but spend several days slowly coming into and leaving each port. Hmm.
my $0.02
Jon
I think not...(*poof*)