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Hi Paul.
Answering your subjects in the order you wrote
them.
Your Navy dive tables are less
conservative than the P.A.D.I. dive tables are. P.A.D.I. does that to build
in a WIDE safety factor, since P.A.D.I.
knows that many sport divers are not
necessarily highly trained or diciplined and might make mistakes on depths or
times they stay.
The Navy knows its
divers are professional and highly trained and gives more liberal and longer
bottom times.
I would say a hybrid would be somewhat more
complicated. If you intended to only dive to a maximum of 4 atm/99ft and while
doing so
keep your interior hull pressurized at 2 atm so you
could stay 205 minutes (P.A.D.I. no deco limit) without deco as opposed to a
typical ambient's 20 minute limit
(P.A.D.I. no deco limit) without deco, then your
hull has to be strong enough to withstand 2 atm of outside water pressure
with 1 atm in the hull interior. So it would be
more complicated than a typical ambient hull that
requires no real pressure strength because it uses internal air to counteract
the outside pressure
and therefore doesn't need a pressure hull. But it
would be much simpler, cheaper and less thick than a full 1 atm sub's hull would
have to be. You
only need to have a hull that would be like a
regular 1 atm sub at 33ft. Not that much pressure, but still more than a typical
ambient hull could withstand if that ambient's interior was at 1
atm.
So it would probably be a bit more complicated than
a typical ambient sub construction, but think of it, you could go to 99 ft for
205 minutes instead of just 20 minutes,
that would make it worth it I believe. Most of the
largely unexplored wrecks in my area are just beyond normal scuba depths. The
ones AT scuba depths have all been
picked over mostly. So a lot of the good stuff
is deeper than normal P.A.D.I. scuba depths allow you to go or else to stay very
long. Even though P.A.D.I. dive tables allow
an absolute maximum no deco safe scuba depth of
140ft for only 8 minutes, not many divers except for the advanced techs like to
go that deep because they cannot stay long enough to
enjoy anything with just 8 minutes without deco. So
imagine yourself at only 2 atm or 33 ft of pressure on your body, but
actually diving to 99 feet and staying for a maximum of 205
minutes without any deco! Wouldn't we scuba divers
love it if we could do that! A hybrid like
this would allow us to. I would say it would be worth the extra trouble. What do
you think Paul?
Now I would like to know what hull strength I would
need for a 1 atm pressure vessel to withstand 2 atm of outside water pressure.
Probably have to build it with a safety factor for 3 or so atm
just to make sure it was safe. I wonder what steel
thickness I would need or if a 1/2 inch thick kevlar wing tank would
withstand 2 or 3 atm with 1 atm inside it? Any help here fellas?
Bill.
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