RE: [PSUBS-MAILIST] question for technical divers

[Phil Nuytten <72020.572@compuserve.com>]

Hi, Alec!
        Well. I see the ol' bail-out thread starts again . .I'm not sure if
it originated with you - but here are some previous work/thoughts:
        The spectre of a lingering pressurization seems to cause a sort of
a liquid-bowel syndrome in a number of would-be escapees! How long does it
take to pressure your hull to abient? Wrong question. Question is: what is
your gas uptake during the period of pressurization? Same thing? No, it
isn't. Consider this - when your hull is half flooded - you are at 33 feet
( 2 ats absolute) When your hull is 2/3rds flooded, you're at 66 feet and
so on - shape or volume immaterial. you can take a fair bit of time
flooding up to a deep air depth and then use gas to blow the last 7 or 800
feet. If total pressurization takes, say, 3-4 minutes ( this is fast) only
a minute or less is spent at near full depth, then it's gonzo to the
surface. Ascent time from 1000 feet is just over three minutes with a
modest Steinke-style escape hood or less than two minutes with an
apea-style torpedo lift bag (unlimited class). 600 foot free ascent escapes
are well within the capability of the 'modern submariner' (according to the
USN )  . . and the Brits have demoed 1000 free-ascents.
        Years ago, Mike Gernhardt  ( now "Astronaut Gernhardt"  getting
ready for his 3rd mission to the ISS) worked out the bubble growth dynamics
for an escape and free-ascent from the Newtsuit, at my request. I had
figured from the basic tissue tensions that we should  be able to do this
with virtually no problem. Mike's figures confirmed that we would be within
allowable limits all the way - provided the last phase of the total
pressurization times was kept short.. 
        It is important that your buoyant escape apparatus is large
capacity, shaped to fit through the hatch when fully inflated  ( that is,
above you - it should hook into a chest harness and be first out!) and
contain a 'spare-air' -style minilung to get you through the first few
hundred feet to where you're getting a full 'gush' expansion. If you go
with cabin gas all the way - you risk a hard HPNS whack when you take a
couple of breaths at near full depth - ( and you must - or become a
halibut!)  It is uncomfortable and unnerving - like a deep gas to air
switchback - but not undoable. 
        Seems like we've had this same discussion before - is it archived,
somewhere  . .or  prehaps it was another forum ( or perhaps too many deep
gas 'incidents' ! (G)
Phil Nuytten