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Hi Dino.
You wrote.....
"Has anybody built a sub with 1ATM air normally, but the option to use
2+ATMs
for the occasional deeper wreck dive? Of course, nitrogen bubbles would have to be dealt with as per scuba diving." Some months ago I proposed a similiar idea here to
the group. My idea had you building a 1 atm sub that's interior could be
further pressurized
so it could go deeper than it normally could. I
think my idea came from some of the other members discussing building a 1 atm
sub out of
propane tanks. Some of the expert members here
expressed their beliefs that using a propane tank as a 1 atm sub is not safe for
a variety
of reasons and they believed a regular pressure
hull should be created instead. Some other members who have propane tank subs
already
disagreed with them and believe their hulls are
safe as long as they do not exceed a certain shallow depth.
This discussion caused me to think about a propane
tank that would only normally be used to a relatively shallow depth, being able
to go an
atmosphere or two deeper by pressurizing the
interior of the propane tank to make its hull able to take the stress of going
deeper than it normally could.
Say for instance you have a propane tank sub that
you have only tested to 1 atm (33 ft) and everything was fine at that depth but
you are afraid to go any
deeper because you do not think the hull will take
any more pressure. If you further compressed the interior atmosphere in the
propane tank to say 2 or even
3 atm, your hull would be able to go twice to three
times deeper than you normally would go in your propane tank sub. In other words
you are using your
propane tank sub as a 1 atm sub down to 1 atm, then
just like an ambient sub, you pressurized the interior to 2 atm and you can now
go twice as deep with
the same stresses on your hull because your
interior pressure is pushing outward against the outside water pressure just
like an ambient sub does. This would
make your sub a hybrid of 1 atm and ambient
operation. Although the Hunley did not operate exactly like this, I got the
idea from some similiarities she had to
this idea. The old girl is still teaching!
I thought to myself....Why do this?
Well........one reason would be.....suspose you
normally just want to operate your sub at 1 atm where you live.
You ordinarily do not care to go much deeper than 1
atm in your propane tank sub. You could operate
it as a normal 1 atm sub at 1 atm depth without any worries about having to
adhere to dive tables. So you would have an
advantage over an ambient sub that WOULD have to adhere to dive tables at 33 ft
depth (1 atm).
Now suspose there are occasional times that
you would like to go an atmosphere or two deeper.
Having the ambient capability to further pressurize your
normally 1 atm interior would allow you to go much
deeper.Then of course you would have to adhere to dive tables. This would give
you the option of having a 1 atm sub for shallow
depths and then being able to convert it to ambient
for diving deeper if you wanted to. A hybrid of the 1 atm and ambient systems. I
do not know if anyone has home built anything like this.
Bill Akins.
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