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Re: [PSUBS-MAILIST] question for technical divers
Phil,
If bailing out on air, what about the narcosis factor at 1000'?? I
would think your brain would be a noodle. Also, that would be a pretty
high spike of PPO2 albiet short...
Al
Phil Nuytten wrote:
>
> 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
--
Al Secor ARS: WA3PWX Scuba Instructor SSI PDIC TDI
http://www.geocities.com/SubDiverI