[PSUBS-MAILIST] emergency lift bags

Wed Aug 13 19:18:21 EDT 2014

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We were just spit balling really, we were talking about fixed bags with open bottoms rolled up neatly on the decks.  It stared with a conversation about an inexperienced diver (me) attempting to escape a flooded sub in pitch darkness and near freezing water.  Not knowing witch way is up, seems very scarry to me.  What are my chances of staying calm and going through all the steps to get home safe.  Just seems easier to hit the big red button and go to the surface.
Hank  On Wed, 8/13/14, Alec Smyth via Personal_Submersibles <personal_submersibles at psubs.org> wrote:

 Subject: Re: [PSUBS-MAILIST] emergency lift bags
 To: "Personal Submersibles General Discussion" <personal_submersibles at psubs.org>
 Received: Wednesday, August 13, 2014, 7:09 PM

 Hmmmm...
 if a sub were to have MBTs large enough to surface when
 flooded, it might look like an underwater tanker. Perhaps
 you envision permanently installed lift bags that would pop
 up when activated? Basically a sub with airbags. I don't
 know, if you're flooded you're pressurized, and
 I'd argue it would be more controllable in terms of
 ascent speed to make a swimming escape than to ride the sub
 up. But I do think you might have a point in terms of
 avoiding sinking in the first place. If you had a hull
 breach, hit the valve to deploy the bags and you at least
 avoid sinking too deep. I suppose that makes sense if
 operating over very deep bottoms. In my experience, I think
 I'm always right on the bottom, so don't have any
 further to sink, but if I were diving a wall like Karl
 Stanley's there could be a scenario for this.   

 On Wed,
 Aug 13, 2014 at 6:46 PM, hank pronk via
 Personal_Submersibles <personal_submersibles at psubs.org>
 wrote:

 There was a fatality in a Nekton submarine when a window was
 knocked off by a sinking yacht that was being salvaged.  So
 there are more dangers under the sea than just
 entanglements.  Is it a waste of money compared to
 electronic gadgets that do nothing but impress your
 neighbour.  There was recently a story told about a sub
 going down when near the surface and they were saved in the
 nick of time.  A lift bag system would have been pretty
 handy that day.

 Hank

  Subject: Re: [PSUBS-MAILIST] emergency lift bags

  To: "Personal Submersibles General Discussion"
 <personal_submersibles at psubs.org>

  Received: Wednesday, August 13, 2014, 6:04 PM

  Entangled

  to me is the operative word. These little boats all
 have

  multiple means of surfacing and would not require you
 to

  flood and escape if you had a loss of power, ran out of
 HP

  air, etc. Its really only entanglement that I see as
 likely

  to cause you to bail. However, if you don't rip
 yourself

  free with MBT blown, thrusters pushing, and emergency
 weight

  dropped, then you would probably need an awfully big
 lift

  bag to make a significant difference to the situation.
 Or

  think of it another way... you already have lift bags,
 they

  are called MBTs.

  Alec

  On Wed,

  Aug 13, 2014 at 5:30 PM, hank pronk via

  Personal_Submersibles <personal_submersibles at psubs.org>

  wrote:

  When

  talking with a friend about escaping from a submarine,
 he

  asked why can't your sub have a lift bag capable of

  raising the sub even when full of water.  I could not
 give

  a good reason why not.  A large volume of air would be

  needed of coarse.  Some fast math on a napkin revealed
 that

  6 80cuft scuba tanks could raise Gamma from 600 feet.
  Two

  240cu ft tanks strapped to the bottom of a sub and two
 lift

  bags, one at each end  could do it.  Why bail out why
 not

  just raise the whole thing unless your tangled and stuck
 of

  coarse.

  Just a thought

  Hank

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