Science Questions

Do submariners ears pop?

Sun, 14th Mar 2010

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Question

Andrea Lewis, Tasmania asked:

Do submariners ears pop?

Answer

Helen -  No their ears probably don't pop because in fact, unlike a scuba diver who takes down a tank of air and breathes it at pressure that is equal to the water around them—which becomes very high very quickly as you go down—submarines are pressurised so that inside them they maintain the same pressure as air at the sea surface (1 atmosphere or atm: the unit we use to measure pressure).  Whereas when you're scuba diving, you could be breathing air at something more like 20 atmospheres, which is much more dense.  It’s that pressure that makes your ears pop and you haven’t got that in submarines.  You may get a bit of compression as you're going down in a submarine as some of that pressure from the water is pushing in on the metal structure and the air inside.  But I think that’s fairly minor, I imagine. 
They build submarines fairly tough so that they can withstand all this pressure without collapsing inwards.  So no, submariners don't have popping ears and interestingly and importantly, it means that if you have an accident, deep down and you have to escape from a submarine, you won't get the bends because you haven’t been breathing air at pressure.  You haven’t filled up your system with nitrogen which will then bubble out of your blood if you're scuba diving and you come up too quickly.  Same thing doesn’t happen in the submariners.  Submariners are trained to be able to hold their breath for long enough to swim a long, long way up from the bottom of the seabed to the surface and survive if there’s a problem down below.

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Andrea Lewis asked the Naked Scientists: Greetings from the other side of the world! Love the podcast - completely addicted! My question is when you go up in a plane your ears pop due to changes in pressure, does the same thing happen when you go down in a submarine? Many thanks Andrea Hobart, Tasmania Australia What do you think? Andrea Lewis , Thu, 14th Jan 2010

The pressure inside an aircraft is not held constant. While it is pressurised to some extent, it does decrease with altitude. This saves fuel and increases the service life of the aircraft, and it's why we experience effects on our ears and sinuses.

However, it seems unlikely that the pressure inside a submarine could be increased very much to help reduce the pressure difference between the inside and the outside of the hull. Because water is so dense (compared to air), during a dive, the rate of change of the internal pressure would be very great if it was to have any benefit to the structure of the submarine. Such a rate of change would not only be very uncomfortable for the crew, it would be very dangerous as it could induce "the bends" when the submarine climbed towards the surface.

In submarines, the air is probably maintained at close to sea level atmospheric pressure, in which case, as submarines change depth the submariners will not experience the same effects we experience in aeroplanes. I think!

Geezer, Thu, 14th Jan 2010



That sounds like a practical joke to me: someone replaces the taut string with a longer one when the victim isn't looking.
A chest height string drooping to touch the floor would represent ~10% change in width, I doubt there would even be a 1% change in dimensions at depth. RD, Thu, 14th Jan 2010



That sounds like a practical joke to me: someone replaces the taut string with a longer one when the victim isn't looking.
A chest height string drooping to touch the floor would represent ~10% change in width, I doubt there would even be a 1% change in dimensions at depth.


I think the string was made of "nautical yarn" Geezer, Thu, 14th Jan 2010

No - it is true-  my nephew is a submariner. And when he comes back from from sea duty he has problems with his ears - but not while at sea. JimBob, Thu, 14th Jan 2010

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