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Hi Joe.
I have a couple of ideas for you.
First idea....I know that you said previously that
your intent for the octopus is to use it a lot as a surface boat that will
occasionally dive to shallow depths as an ambient sub.
After posting my last post about using propane
tanks to create a hybrid 1 atm/ambient system, I am wondering if you could fit a
small propane tank into your sub design that would allow you and
the other person to still seat in tandem. Since you
plan to only dive to shallow depths anyway, this way you could operate as a 1
atm sub to perhaps 2 atm and not have to worry about dive tables.
Then if you did decide to go deeper you could do
that also by the system automatically switching to ambient operation beyond 2
atm of depth. The advantage of this over you just making the
octopus
strictly ambient is that if you don't plan to dive
very deep most of the time anyway, it wouldn't automatically pressurize. That
means you would not have to worry about the problems of accending
too
fast after being down a while which can give you
the bends (decompression sickness) as long as you did not go deep enough for the
valves to automatically switch to ambient operation. Remember,
when operating an ambient sub your body is under
the same pressurization as if your body was at that depth in the water. This is
one DISADVANTAGE an ambient sub has that a 1 atm sub does not have,
because a 1 atm sub can rapidly pop to the surface
without any ill effects to your body. This would afford you a margin of safety
in that you would not only NOT have to worry about dive tables, but you would
not have
to worry about emergency accents or unexpected
accents that could injure your body if done too rapidly in an ambient sub. I
thought this might be a good thing for you to consider Joe.
Second idea.
I was reading Doug Jackson's sub site at this
link.... http://www.submarineboat.com/
Go to his site and look for the contents heading of
"Evolution of Design". Then scroll down to just a little before the bottom of
the page and you will find this paragraph.......
"5. The hatch was designed to open outward after testing in a card board
mock up, but now that I can test with the real cabin, it is easy to see that
opening it inward is not really a problem. And opening it inward is much easier
to seal and safer, since the pressure on the hatch when submerged naturally
wants to push the hatch outward. This is a trait of ambient submarines and
opposite of their 1 atm (atmosphere) cousins."
If you do decide to build the octopus to be
strictly an ambient sub, you might think about if you would want to install your
hatch to open inward as he has. Since an ambient sub has internal pressure that
pushes outward against the interior of the sub's hatch,
Doug reasoned that the hatch would seal better when
closed if designed to open inward. If you ever got stuck on the bottom and had
to bail out of your sub, you would have to open your scuttle valve and use a
bail out tank and wait for the water to enter your sub
and equalize the pressure so you could open the
hatch inward. You would have to do this in a 1 atm sub too. The only difference
would be that with the ambient sub's hatch opening inward, your internal air
pressure is pushing it against its flange seal, whereas in a 1 atm sub the water
pressure is pushing it the opposite way against its flange
seal.
I didn't know if you had considered the differences
regarding hatch installation between 1 atm and ambient systems Joe.
That is the end of my two ideas for you. But now I
have a question for myself and others here. Since it is easier and safer to open
an ambient hatch inward, as opposed to opening a 1 atm hatch outward, how would
someone install a hatch
that would go on a 1 atm/ambient hybrid sub like I
have described previously? Sometimes you may only use the hybrid as a 1
atm sub for a given dive. Other times you may decend a bit deeper and
automatically switch to ambient operation.
Which way would someone install the hatch in
this situation? This one has me puzzled. Anyone have any idea?
Bill Akins.
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