[PSUBS-MAILIST] escape pod

[hank pronk via Personal_Submersibles]

Hi All,
I had an idea this morning while considering the entanglement risk for a dive I am planning.  A submarine could be built or refitted with an escape pod.  The rear head of the hull could be removed and a ring welded much the same as if you were converting to a  dome.  A sphere could be built with a matching ring and hatch.  The sphere would seal with a simple O-ring.  If you need to escape the sub, just crawl into the sphere, close the hatch, wait for the sub to flood and release the sphere to float to the surface.  I am sure this has been done somewhere on something.  
Hank