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Author Topic: Would swimming from a submarine cause the bends?  (Read 4274 times)

Offline Fozzie

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Would swimming from a submarine cause the bends?
« on: 08/07/2011 19:30:02 »
Chris Martin  asked the Naked Scientists:
   
If I escaped from a submarine at 50m or more and held my breath all the way up, would I still get the bends?

Thanks,
Chris Martin
Mark, Somerset

What do you think?
« Last Edit: 08/07/2011 19:30:02 by _system »


 

Offline Airthumbs

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Would swimming from a submarine cause the bends?
« Reply #1 on: 07/07/2011 19:14:45 »
The world record for a human descending to the greatest depth on a single lungful of air, without fins or flippers is 101m!  The world record for No Limits Freediving, where the diver is pulled down by a sled and then uses an air bag to resurface, is 214m!

The British Freediving Association, http://www.britishfreediving.org/index.asp?sec=1, states that these divers ascend at 3-4m/s.  To avoid getting the bends the divers usually let go of the airbag at about 20-30m and then slowly ascend the last part of the return to the surface.

This video is now not the official world record but interesting none the less,

If you were to attempt to resurface from a submarine at 50m depth by holding your breath you would suffer catastrophic injury in your lungs due to the expansion of air.  One technique to avoid this is to literally scream all the way up.  However without such a device as a Steinke Hood you may also suffer fatal injury... http://en.wikipedia.org/wiki/Steinke_hood
« Last Edit: 07/07/2011 19:22:07 by Airthumbs »
 

Offline CliffordK

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Would swimming from a submarine cause the bends?
« Reply #2 on: 07/07/2011 20:15:47 »
The bends is caused by nitrogen dissolved in your blood under pressure, then moving to a lower pressure and creating bubbles in your blood.

Somewhat like carbon dioxide will bubble in your soda pop.

Submarines are usually maintained at 1 ATM pressure, and thus you would not suffer from the bends going from submarine air to atmospheric air.

The problem is the transition phase from the submarine environment to the deep sea environment, and back to the surface environment. 

You would have to have some kind of airlock to move from the submarine to the underwater environment.

http://en.wikipedia.org/wiki/Escape_trunk

There is a time dependent component of the Bends.  If the escape from the sub could be made quickly, then the risk would be minimal.  However, a rescue ship should have a compression chamber available just in case.

Whales apparently avoid the bends by exhaling most of their air at the surface before diving.
 

Offline Airthumbs

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Would swimming from a submarine cause the bends?
« Reply #3 on: 07/07/2011 23:10:54 »
Whales apparently avoid the bends by exhaling most of their air at the surface before diving.

It has been theorised that whales avoid the bends by making repeated stops as they rise to the surface.  However, scientists have discovered evidence of "the bends" in whale bones upto 100 years old.  Recently it seems that military sonar is possibly a cause of the bends in whales as they panic and rise to the surface too rapidly in an attempt to escape, thus suffering from the bends.  http://news.bbc.co.uk/2/hi/science/nature/4122119.stm

Another way that I have read it might be possible for a person to escape from a submarine is via one of the torpedo tubes.  Even so it is a frightening prospect having to escape from a submarine, but I would count myself lucky if the depth was only 50m.   :-\

 

Offline CliffordK

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Would swimming from a submarine cause the bends?
« Reply #4 on: 08/07/2011 06:10:55 »
Another way that I have read it might be possible for a person to escape from a submarine is via one of the torpedo tubes.  Even so it is a frightening prospect having to escape from a submarine, but I would count myself lucky if the depth was only 50m.   :-\
I was thinking of the torpedo tubes.  Depending on how they open, the rush of water filling them would be terrifying.  But, it would be an effective, and rather quick airlock.

There are a few rare reports of survivors of WWII sunken subs escaping through the torpedo tubes, including 14 to 18 survivors from the sub U1195.

But, there are also reports of submarine crews that were stuck in excess of a day waiting for their air to run out, sometimes with communications with ineffective rescue crews outside of the sub.

I think I'd risk the bends and some time in a hyperbaric chamber vs slow suffocation or drowning.

Here is an interesting quote about submarine escape techniques.

The Royal Navy later adopted the practice of blow and go, in which the sailor would exhale continuously during ascent to avoid air expanding in the lungs, which could cause them to rupture. Postwar, submariner Walter F. Schlech, Jr., among others, examined submerged escape without breathing devices and discovered ascent was possible from as deep as 300 ft (91 m): "in one sense, the Momsen Lung concept may have killed far more submariners than it rescued".
 

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Would swimming from a submarine cause the bends?
« Reply #4 on: 08/07/2011 06:10:55 »

 

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