Re: [PSUBS-MAILIST] PSUB Fatalities...

["Sean T. Stevenson" <ststev@uniserve.com>]

Carrying a bottle of heliox 16 as escape SCUBA gas would permit an
escape from up to 90 meters.  Of course, you'd probably sustain a bend
escaping from that depth, but then bends you can cure... drowning you
do not.

-Sean


On Sun, 5 Mar 2000 22:19:14 -0000, Captain Nemo wrote:

>
>Gabriel,
>
>In almost 40 years of diving, I've used a lift bag or two.  When they don't
>fail, they do take time to inflate; during which I like to breathe.  SCUBA
>enables me to do this.
>
>A two ton sub could need a 62.5 cubic foot bag to float neutral at the
>surface; that same bag requires 125 cubic feet of air at a 33-foot depth;
>187.5 at 66; 250 at 99; and so forth.  I can't hold my breath as long as it
>will take to transfer that much air into the bag, arrest the descent, return
>to the surface, exit the hull, and get back up to where I can breathe, so
>I'll take SCUBA.
>
>I realize the forces I'll encounter if a window breaks will be extreme, and
>I won't be able to exit against the incoming water pressure.  But  if the
>stricken subs rate of descent exceeds a lift-devices rate of inflation,
>she's going to the bottom, bag or no bag.  In any event, I'd choose being
>able to breathe over not having that option.
>
>And if, say,  the boat gets a slow leak that causes us to go negatively
>buoyant; or the ballast system fails and the sub bottoms out with the
>pressure hull intact; I'm going to need to open the flood valves, equalize
>pressure,  and escape.  That's going to take time; and then there's the swim
>to the surface.  Again, I'll take SCUBA.
>
>With further consideration, I can visualize several other instances where
>onboard SCUBA might be vital, and none where it would be undesirable.
>Therefore, I don't see any reason not to carry it.
>
>Personally, I apply the same logic to diving and submarines that I used
>while skydiving and flying; I never tell myself I'm "safe".  I always expect
>the worst.  When seconds count, that preparedness decreases reaction time;
>and the availability of survival equipment can mean the difference between
>life or death.  I wouldn't climb into an experimental aircraft without a
>parachute, or make a jump without a reserve; or dive without a "safe second"
>on my rig and a buddy beside me.   By the same token, I won't operate a
>homebuilt submarine without SCUBA onboard.
>
>In the interest of safety, we restrict the operation of our experimental
>homebuilt submarine to sites where maximum depth does not exceed
>recreational diving limits; we always have support divers in the water;
>emergency plans in readiness; and we carry SCUBA for all those instances
>where doing so might save lives.
>
>I've gone down in professionally built submarines without SCUBA, but the
>engineering and construction of those boats is up to a standard that most
>homebuilts do not approach.  It's the difference between a 747 and a
>SONNERAI: I don't wear a parachute on an airliner, either; but we're talking
>about two entirely different levels of risk when we compare commercial
>vehicles to experimental homebuilts.
>
>I respect everyone elses right to live their lives, and operate their own
>homebuilt submarines in the manner they feel safest with.  But personally,
>if there isn't SCUBA aboard their homebuilt sub, I wouldn't want to be their
>passenger.
>
>Very best regards,
>
>Pat Regan
>vulcania@interpac.net