How do they power the big cruise ships?
My wife and I were watching TV last night and a commercial for a cruise line came on and I couldn’t come up with a good answer for her. I assume they’ve got some big deisels in there, but if so where do they carry the fuel?
Anywhoo. . .
Derf
Diesel engines, both for propulsion and for the huge electrical load. Nuclear-powered cruise ships have yet to gain the public’s trust 
Thanks ts. . .
Follow up:
So how much fuel do those big diesels use? And where is it stored?
I used to work on one… I don’t recall actual figures, but it was astronomical… something like one gallon of fuel for every inch it moves.
one mile = apx 60,000 in (rounding)
so 60,000 gal/mile
it’s apx 800 miles from NY to Bermuda (lets say 1000 to make the numbers easy). so this trip will consume 60,000,000 gal of fuel at a cost of $1/gal (again rough estimate) = $60 mil fuel cost?!?
Also using 1 gal = 0.134 cu ft we get about 8 million cubic feet which works out to a cube tank with the outer dimentions of apx 1 mile x 1 mile x 1 mile
Hi, TheDerf! Welcome to the SDM…
Oh. Registered 3/99. Poster ID # 182.
Hey, you’re averaging about one post per 6 months! Cool!
Anyway, I found a cite that the average cruise ship consumes 15,000 gallons a day of fuel oil at full speed, and an average of 8000 gallons a day at normal operating speed. This was for the “radisson diamond”
http://www.cruisingreview.com/600702030101.html
Yeah, that figure is obviously totally wrong… like I said, I didn’t recall exact figures, I just knew it was something amazing…
.Datasheet of a smallish (350 passengers/225 crew) cruise ship..
Tank capacity: 182300 gal (about 690,000 l = 690 m^3). Assuming a density of 900 kg/m^3 (I don’t have an exact number but take a middle value between automotive diesel and heavy fuel oil) this would be about 620 metric tons or about 5.3 % of the ship’s total displacement. Not trivial but doable to design tanks of that relative size in.
The data sheet quotes a range of 4000 nm = 7408 km at 14 knots. This translates to a fuel consumption of 93.1 liters per km = 0.025 mpg. Multiplying by 575 head of (passenger + crew) this is equivalent to everyone on board driving the distance in a car with a fuel consumption of 14.4 mpg.
The propulsion is usually supplied by a diesel-electric combination system. The diesels run generators to supply a steady source of power; the propellors are turned by electric motors. The size of each depends on the size (and desired speed) of the vessel.
Older ships (and they don’t have to be that old) have the electric motors mounted within the hull with shafts running out to the screws. Many newer vessels have pod systems, where the motor is mounted in a pod below the hull. This reduces shaft length (and weight) and sometimes allows the ship to be built without rudders (since the pods can be turned for directional control, just like the Evinrude on a 16 foot runabout). Of course, the trade-off is that maintenance at sea is a bit of a bother, since the motors are not up in the hull with easy access.
The size of the engines and motors can vary widely. For the M.V. Elation, (from which I got the azipod photo link, above), there are six diesels providing a total of 47,520kW (64,600hp).
Many propulsion types and their components are displayed on this page.
Fuel is carried in bunkers in the lower hull. This photo shows a new hull being laid in front of a (nearly?) completed ship in the same dock. Note the several chambers in the just-begun hull. These can be fitted with tanks to hold either fuel or ballast water. Based on the tiny human figure on the lower left of the photo, I would guess that that section is 35 feet/10.7 meters wide and 10-12 feet/3 - 3.6 meters high. Extend that down the length of the hull and you can store quite a bit of fuel or water.
On some ships, the bunkers are mounted along the sides, instead of near the keel, but I have never sailed one that had that configuration.
Wow. All I can say is that I’m stunned. :eek:
I love the dope.’’
(BTW, I’ve lurked since nearly the beginning, I remember for instance when it was moved here from AOHell. . . I just don’t post much. . . 
)
Quite a few newer ones are powered by gas turbines, also with electric drive systems. They tend to have cleaner emissions than diesels, a consideration in a number of ports including in Alaska. A number of older ships, mainly converted passenger liners, have steam turbines.
You might find more info at the sites of the 3 shipyard that supply most of the industry:
Kvaerner-Masa in Finland
www.chantiersatlantique.comChantiers de l’Atlantique in France
[url=www.ts.camcom.it/strutture/fincantieri.htm]Fincantieri in Italy