I’m sure we must have some Naval veterans around here.
If you’re serving on a submarine, how long are you in the sub, and how much of that time is actually spent underwater?
Under normal peacetime circumstances, what is the longest single period a sub might stay submerged?
IIRC for boomers they deploy for around 2-3 months. They stay submerged the whole time. The main thing limiting their time at see is available food on board.
Fast boats I think do more calls to various ports and will not stay submerged for as long (although they could again with the limiting factor being the amount of food they are carrying with them).
How long has the Kursk been down now?
(sorry, I can never resist a set up like that, NDI)
Ballistic missile submarines conduct 80-day or so patrols. Once they leave port and submerge, they are on “alert” and are submerged continuously.
Fast attack submarines alternate between “weekly ops” (which actually range from a week to a few weeks) at sea, and deployments (which typically go for about 6 months). Once they leave port and submerge, submarines are submerged essentially continuously. The only reason a submarine would surface would be to drive back into port, or if there were an emergency. Fast-attack submarines do go to periscope depth routinely, though. Also, fast attack submarines typically get a foreign port visit or two during a deployment.
All submarines are limited solely by the amount of food onboard. Toward the end of a deployment, the meals get interesting (chili mac with a side of canned beets, for example).
The longest that I’ve been submerged was about four months, followed by two quick port visits, followed by two months at sea. At the end of the four months, we were getting somewhat low on food, but this was partially due to poor planning by the sub’s Supply Officer. (In his defense, the port visit had originally been planned for the three-month mark.) We could have easily stayed out longer if we’d packed more food.
Not as long as the USS Thresher.
How are potential crew members tested before they’re allowed to serve on board such a boat? Do people every just lose it underwater?
Someone on the boards suggested duty on board a military submarine was the closest we might get to duty onboard the USS Enterprise (Captain Kirk’s vessel I mean of course :)) It really does seem that way.
Since food is the primary limit to deployment time, robotic bubble heads could significantly extend patrol times, right? Or are there other factors that could affect the submariner’s deployment durration, assuming an unlimited food supply?
I should clarify that I am referring to modern nuclear-powered submarines. Also, my comments are specific to U.S. submarines (all of which are nuclear-powered.)
I once took a guided tour of an L.A. class attack sub. The officer who was showing us around mentioned that they’d once had a cruise extended because of mechanical problems with the boat that was replacing them, and they’d spent the last two weeks at sea eating nothing but pancakes.
I’ve always heard that a psychological test is administered to prospective submariners, but I was never tested. I never saw anyone really lose it at sea, but some came close. If someone does lose it, straitjackets are available. 
I agree. In fact, it is my understanding that the newest Virginia-class submarines even include large screen displays in the ship’s control room on which images from the photonics masts (which have replaced the periscopes) can be displayed, along with other sensor information.
Sure, assuming they know how to operate and maintain the submarine and its nuclear reactor, and fix things when they break.
In fact, the U.S. Navy (especially the nuclear submarine force) has traditionally eschewed automation. Less automation means fewer things to break. More personnel means more sailors available for maintenance, repair, and damage control.
Some other limiting factors might be spare parts or repairs unable to be completed by the crew.
Re: Food Supplies - Does this mean submarines are so packed so full at launch time they can’t add some spare food? And that brings up another question, do they ever eject anything from a sub when it’s submerged (aside from those missiles)?
Trash, I believe. In the days of U-boats and fleet boats every spare nook and cranny would have bunches of bananas, oranges, etc. stuffed in them (including one of the heads).
I believe the Hunley beats them both, although it has since been raised.
I don’t know about the most modern ones, but the old sub from the sixties I was in ejected the sewage out the bottom. Apparently the sonar dudes could hear the shrimp and plankton having a feast when they did that.
When going on deployment, a fast-attack submarine is pretty packed with food. Normally there is a large walk-in refrigerator (reefer) and a freezer. For deployments, both are converted to freezers, for more long-term food storage. This rather stinks, because it means no refrigerated fresh food from the start of the deployment.
In addition to all the normal storage holds and lockers being packed with food, every non-operational deck space in the forward compartment (this includes berthing areas, passageways, etc., but does not include the control room, for example) is covered with No. 10 cans of food. The cans are then covered with rubber matting. This means that you spend the first few months of the deployment walking on food, and ducking your head.
Storing food in the reactor compartment was prohibited (and inaccessible, too, of course) and storing food in the engine room was discouraged. You could store food in the engine room if there was no other option, but it was somewhat of a last resort. We did store several pallets of eggs in a bilge area where it was cool in the engine room.
Ballistic missile submarines are much larger, and conduct shorter patrols, so food storage is much less of an issue. The food needed for a typical patrol can be largely stored in the normal food storage holds and lockers.
Trash disposal is conducted through the trash disposal unit (TDU), which is like a 12-inch diameter vertical torpedo tube. Trash is packed in sheet-metal containers, weighted down and shot out. While the U.S. Navy has been trying to be more environmentally-friendly in recent years, there’s really no room to store all the trash generated onboard a submarine. Trash is only disposed of in very deep water.
Sewage is pumped or blown directly to sea, so long as the submarine is more than 12 miles from the nearest land (IIRC).
Interestingly, nuclear submarines make their own oxygen by separating it from seawater – an energy-intensive process, but they have reactors producing an abundance of power. Note that the process of separating H2O will produce two hydrogen atoms for every oxygen atom. Hydrogen is flammable, so what do they do with it?
In order to avoid audibly venting gas bubbles (which, at depth, would have to be forced out, a noisy process) the hydrogen is released slowly and silently through a diffuser.
So submarines fart.
The silent, but deadly, service.
Average submerge time? Well, if they are in the Mariana Trench, I think we all know how long.
Seriously though, it seems we have an answer for larger subs. I wonder what the answer is for small 1-2 man submersibles.
I go back to the diesel Submarines. Submerged you had two battery wells 126 1 ton batteries in each well , when the batteries depleated you stopped. You either surfaced or came to snorkel depth and recharged the batteries. If you got caught you surfaced and kicked in four Fairbanks Morse 1700 horse power diesel engines and ran like hell. Top speed was about 20 knots. Also you had problems with oxygen running out…I have been submerged so long that people were passing out. Submarines were called Pig Boats because after being on a thirty day patrol it was raunchy…no showers at sea on these boats. You got a finger of fresh water each morning to brush your teeth and wash your “whatever”. The submarines of today even carry women… Would not have been possible on the diesel boats…
May be wrong, but I thought the problem was build up of CO2, not the lack of oxygen as such.