[QUOTE=Spezza]
2 hours to get underway, eh? Tuchman does mention that, at one point, the captain keeps the boilers stoked to be ready to make flight with 15 minutes notice.
[/QUOTE]
Right - to be ready to go on short notice, the steam plant would have to be hot. This certainly consumes fuel, though nothing like as much as when underway. (The analogy would be a car that’s idling.)
(Note that “weigh anchor” means to hoist it aboard, as when getting underway.) Even when anchored and not underway, it would be necessary to keep the steam plant warm: you’d need electricity and water, and anchors are notoriously flaky - they can drag, in which case you’d better be able to move under your own power pronto.
Not sure I understand this question - except for a sailing ship, all ships move only by burning fuel.
Not much - well less than one percent.
Not too much - perhaps a percent or so per day.
Depends on the bunker (i.e. fuel) capacity and greatly on the speed at which she’s traveling. The hourly rate of fuel consumption at max power could easily be 5 to 10 times that at “economy cruise”. A very rough estimate for a naval ship at typical speeds might be 10 to 15 days.
There might be, in which case the ship will connect to electrical, fresh water and steam services and the probably shut down its own plant. Otherwise, the ship’s steam plant will operate (at greatly reduced load) to run electrical generators and evaporators (which make fresh water).
There will be condensers that make the steam plant a “closed” cycle (without this, efficiency would be hopeless). But there will always be some leaks, so it is necessary to distill “makeup” water, and to have some reserve in case of a problem - certainly thousands of gallons for a sizeable ship.
Certainly with oil (and probably with coal) efficient combustion is associated with light smoke. So I doubt that dense smoke was a regular or constant thing. But it’s true that a sharp-eyed lookout may well see smoke when a ship is below the horizon.
Weather or night might conceal dense smoke. But once it’s floating around in broad daylight, I’ve never heard of any technology that could conceal it.