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It's common in submarine movies that when suffering some kind of shock (like a near miss by a torpedo or falling deep into a trench), water will start bursting into the cabin and the crew will run around turning little wheels or cranks to stop the leaks.

Is this realistic? What are those wheels doing? Is it even plausible for a submarine to leak without a catastrophic failure?

Rodrigo de Azevedo
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Rag
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1 Answers1

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I think that the "cranks" you're talking about are the vent valves that allow air circulation between compartments inside the submarine, which are normally left open in order to allow the air purification equipment to provide clean air to each compartment and remove the stale air.

If a leak from the outside occurs in one compartment, these valves would allow it to flood the entire submarine. Therefore, it is best if the valves for that compartment can be closed, which would allow the rest of the compartments to continue to operate normally. Second best is to close the valves of all of the other compartments, which will allow the air system to flood in addition to the affected compartment and prevent all compartments from getting new air. In this case, it is necessary to surface ASAP.

However, in deep-water events, all of this is for naught, because the bulkheads between compartments are not nearly as strong as the pressure hull, and they will fail regardless of the state of the valves. The only way a crew can survive for any significant length of time is if the pressure hull is still intact. Anything to the contrary you see in movies is mostly "dramatic license".

Dave Tweed
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  • Also, depending on the age of the submarine in use, there may be manual "emergency surface" valves. At least that is what the tour guides say on the tour of [U-505](http://www.msichicago.org/explore/whats-here/exhibits/u-505-submarine/). – hazzey Sep 26 '16 at 01:30
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    I agree with most of this however, I believe a good portion of the valves that are shown as closing within the movies are the fluid pipes that are run within the submarine which are being shut off similar to plumbing in your house. If a hard water line is ran from the wall shutoff to your toilet and the toilet shifts that hardline can crack or break and you'd shutoff the wall shutoff to stop the leak then repair the crack - same philosophy. – Dopeybob435 Sep 26 '16 at 13:05
  • I suspect the earliest 20-th century subs had weaker hulls -- or stronger bulkheads in relative terms, so at least in theory a punched hole, rather than collapse of part of the hull, might not be fatal. (Note that I'm not going to analyze those US Civil War submarines :-) ) – Carl Witthoft Sep 26 '16 at 15:05
  • Submarine hull failures are generally a result of two factors - excessive pressure on the pressure hull and rivet/weld/fitment failure. In the movies the valves the actors spin to shut off the incoming water are realistic, but in fact are only associated with internal air and fluid lines, there is no way external hull pressure is experienced inside the pressure hull within a small pipe in the habitable parts of the boat. (Submarines are BOATS, not ships). – Donald Gibson Nov 20 '16 at 17:40