Pressuring 1 ATM Subs

[SJSVOB@aol.com]

If you really wanted to dive deep you could pressurize your inner hull making
sure you keep in mind your SCUBA diving training that all psubbers have gone
through, right?  (Of course if you really know your stuff, you'd be using
mixed gasses.)  But this brings up an important point on using ambient subs
(or 1 atm subs which are pressurized to go deeper), which I don't recall
hearing mentioned here: 

You must be very very careful to maintain the proper depth with your sub.  If
due to some accident your sub were to surface too quickly you could be killed.

I heard of a case where a diver was in the lock out chamber of a sub.  As they
pumped the gas out of the airlock the gas was flowing and remaining trapped
under some structural modifications which were recently made to the sub.  This
caused the sub to become positively bouyant and the sub quickly rose to the
surface, killing the diver in the lock out chamber while the operator watched
through the viewport.  In a 1 atm sub you can always blow ballast to save your
ass if need be.  In other designs you must always make a controlled ascent,
which could be impossible if you experience a failure in your dive planes or
ballast tanks.  I'd feel safe in an ambient wet sub that I could jump (ok
float) off of, but a dry ambient sub seems rather dangerous to me.