A nuclear attack submarine carrying a crew of, at least, a hundred people went missing in the North Atlantic Ocean, its last known location was the Bermuda Triangle where ships and planes have vanished. Cutting to the chase; the sub has traveled back in time several hundreds of millions of years into the Jurassic period. How likely is it for the crew to survive a whole year in the Jurassic sea and maybe surface once in a while for a cigarette break? Assuming it was on its maiden voyage in crossing the Atlantic Ocean when it mysteriously got lost inside the Davy Jones's locker.
6$\begingroup$ So are you asking how long can the crew survive or how long the sub can survive? The title doesn't match the content here. Just because the sub is busted, doesn't necessarily mean the crews are goners. $\endgroup$– 絢瀬絵里Jan 1, 2017 at 18:31
1$\begingroup$ @AyaseEri, I thought of the opposite: Just because the crew starves to death (or whatever) doesn't mean the sub wouldn't be in operational condition if you came across it a few years later. $\endgroup$– WildcardJan 2, 2017 at 11:24
1$\begingroup$ @AyaseEri: I did mentioned operational and survive, do you mean the sub can operated by itself? $\endgroup$– user6760Jan 2, 2017 at 13:23
$\begingroup$ Sub survived as long as it remains functional. It doesn't have to be actively operated to be called so. Just like Wildcard said. $\endgroup$– 絢瀬絵里Jan 3, 2017 at 1:29
In addition to the food mentioned by James K, spares will become a problem sooner or later. Parts wear out. They are supposed to be replaced before they break. The sub has an engineering crew which can probably jury-rigg some parts, but not everything.
The US Navy uses submarine tenders to maintain subs at remote locations. Look at the crew numbers -- ten times as many as a submarine. Quite a lot of them are maintenance specialists.
$\begingroup$ I can't see any mention of the crew count on wiki page you linked, or pages about specific ships of that class. $\endgroup$– M i echJan 1, 2017 at 14:42
5$\begingroup$ @m-i-ech, in the data info box on the right side it says "Complement: 1,350". That is the crew count. $\endgroup$ Jan 1, 2017 at 16:25
$\begingroup$ This doesn't answer the actual question: "how long?". Yes, spare parts will wear out. But when? In 5 months? 5 years? Submarines are designed to operate for long time periods before returning to port. $\endgroup$– vszMar 16, 2020 at 14:38
$\begingroup$ @vsz, I referenced the answer by James K for the food limit, which I didn't want to repeat. If you ask me, his answer could have been accepted just as well as mine. $\endgroup$– o.m.Mar 16, 2020 at 16:18
The problem the crew will face is that during the Jurassic period the CO2 level of the atmosphere is 5-10 times higher (2000 - 4000 ppm) than the current level (400 ppm) and the oxygen content was on an all-time low of 15% in the beginning which rised to 26% at the end of the Jurassic (in comparison to 21% now):
Graphic from author Robert Rohde from the Global Warming Art project licensed under CC BY-SA 3.0
The interesting things are the blue line and the points with crosses which are actual measurements. While it looks not so bad at first, there is evidence for very high levels (2000 - 4000 ppm).
The run-away greenhouse effect caused global warming at a level which is hard to imagine now. Nearly everywhere the climate is tropical, extremely hot (40°C+) and very hard to cope with. In the Jurassic era the continents begin to split up to form our modern ones, the Atlantic ocean is only looking like a big saltwater lake.
Image from wikicommons, Dr. Ron Blakey, under Public Domain
The sea level is much, much higher than now (missing ice), so navigation are mostly useless (What does work is the gyrocompass, echo sounding and astronomic navigation). The ocean is nearly everywhere over 25° warm, up to 30°C at the equator and 19°C at the poles, so expect terrible hurricanes forming at the coast.
Some hints apart from the climate and the occasional plesiosaur sticking out the head of the water that they are not in Kansas anymore:
The day lasts only approximately 23 hours (tidal slowdown).
The moon is looking bigger (It is nearer to Earth).
The magnetic compass shows in the completely wrong direction (the magnetic pole is wandering and sometimes even reversing direction).
The sky looks foreign. The sun revolves the galaxy once in 220 million years, so the Earth is in the wrong position. It is still possible to use astronomical navigation for several purposes, but the crew must prepare their own observations.
Light sensors show that the sun radiation is slightly reduced by 3%.
The submarine has fortunately CO2 removers, air conditioning and could produce oxygen with electrolysis, so it may be comfortable, but they may want enter land sooner or later.
The effect of 2000-4000 ppm carbon dioxide and low oxygen content is that the air feels suffocatingly bad, you get headaches, are lethargic and feel like drunk.. While the article on carbon dioxide poisoning claims that human can adjust to levels up to 10 000 ppm permanently, the time will be unpleasant (In this case don't forget that if they come back the air smells fantastic).
Anyway, your crew will suffer. High temperatures together with high humidity and bad air will cause very high stress levels.
6$\begingroup$ When they're buttoned up, they can use their CO2 scrubbing machinery to keep the CO2 in a human-comfortable range. This means more wear/tear on the scrubbers, which might be a useful plot detail. $\endgroup$– CatalystJan 1, 2017 at 21:21
1$\begingroup$ @Catalyst That depends on whether it's even designed to be able to deal with such high levels of CO$_2$ concentration. It's perfectly possible that it isn't built to work for prolonged periods of time in conditions 10x worse than what you'd normally encounter. You can't necessarily just crank it up to ten and all that will happen is reduce the expected lifespan of the equipment by a similar degree. $\endgroup$– userJan 1, 2017 at 21:32
4$\begingroup$ @MichaelKjörling I do not see it as a problem, modern submarines can principally operate years under water without emerging to the surface, so the scrubbers should be able to handle this level as long as the air is not exchanged too often. I wonder if modern submarines still have escape sets which can be modified to allow longer land stopovers. $\endgroup$ Jan 1, 2017 at 21:43
3$\begingroup$ @John I have read "One of our submarines" which is the story of a British sub operating in the tropics. Without air conditioning it is not fun, everything is wet and hot, people are sweating profusely and things are running to seed. In fact, I would recommend that the story breaks the air conditioning for some time to let the crew love its proper functioning. :) $\endgroup$ Jan 1, 2017 at 23:47
3$\begingroup$ @Michael it arrives on earth and not in space that had has already been waved. $\endgroup$– JohnJan 2, 2017 at 2:44
Food is the limiting factor.
The nuclear motor can operate for 25 years, and it has desalinators, active CO2 scrubbers and oxygenators to provide air and water for the crew for as long as it has power.
This article, which concerns the British Sub, Artful, notes that a normal deployment lasts 10 weeks, and a sub won't carry enough food for a year. It would be possible for the crew to survive on short rations for a while, but a full year is probably too long for the whole crew to survive without finding another source of food.
The natural place to find food would be fishing. Fortunately Wikipedia has a category on Jurassic fish.
2$\begingroup$ They could also hunt, of course. As a warship the vessel will have small arms aboard which could be used to gather some interesting meats for dinner. $\endgroup$ Jan 6, 2017 at 0:15