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Sorry for coming into this
convo. so late, but in my design ideas I had similar thoughts as Ken. In
the end I compromised by simply adding a garaged utility ROV. Any work,
video, etc. can be done by the bot via umbilical to the sub. This keeps
the weight of the sub down and maintains hydrodynamics, not to mention extending
the subs reach without installing external actuators (cranes, arms, etc.).
IDEALLY, this would be a wireless system so if the bot got stuck it wouldnt
compromise the sub; but I'm sure a detachment safety feature could be
devised.
For now, from what I know,
your mid-water work is simply done with a diving bell on a crane or suface
support vessel. If they need to change stations the divers simply hop in
the bell and the boat moves to the next location. The bell stays at
pressure and when it comes up they go straight to the chamber for slow
decompression. It's the K.I.S.S. method I guess.
just my 2 cents,
Shawn
----- Original Message -----
Sent: Saturday, May 26, 2007 3:35
PM
Subject: Re: [PSUBS-MAILIST] VBT's &
The Apology
Thanks Vance,
That's the exact reply I was looking for in the first place. Thanks
for "breaking it down for me" so that I can understand it.
Ken,
The method has to do with the built in compensating system for weapons
discharge, and the negative tank/varaible ballast system to offset and
control release of heavier equipment (such as their subs). We've got some
Navy guys on line who'll have better information about that kind of thing.
And the point is, of course, that this has been an apples and oranges
conversation. Psubs don't have all those tons of water and pumps and eight
or nine dozen people to cope with these issues. Which IS the point, I
suppose. Vance
-----Original Message-----
From: Ken F
To: personal_submersibles@psubs.org
Sent:
Sat, 26 May 2007 1:09 pm
Subject: Re: [PSUBS-MAILIST] VBT's & The
Apology
Vance, Almost
purely for the sake of argument at this point. It's not un-heard of for a
Naval Submarine to dispatch a squad of SEALS, and all of their equipment,
out through the TORPEDO TUBES, as well as undocking an SDV (submersible
diver vehicle) from the deck of the submarine. With the weight off all
the men, equipment, and SDV, I'd figure it at roughly 2000 to 3000
pounds. So you're telling me that a Naval Submarine intentionally
grounds itself if it's going to offload a ton to a ton and a half of mass,
because there's no safe way of doing it otherwise? I wanted the *method*,
which is where I think you're missing the point.
Ken vbra676539@aol.com wrote:
Age
and evil intentions will outdo youth and smug every time. Deal with it.
What you are suggesting is not new, merely dangerous. Figure a way to
"anchor" in midwater, or perform underway with enough mass (as in military
subs) and you'd be fine. Otherwise, problems compound. Don't take it
personally. I was 23 once, as well. The difference between us is that
you're coping with it and I'm merely glad it's over.
Vance
-----Original Message-----
From: Ken F
To: personal_submersibles@psubs.org
Sent:
Sat, 26 May 2007 4:23 am
Subject: Re: [PSUBS-MAILIST] VBT's & The
Apology
Vance,
Wow, I really had no idea that what I was suggesting was so
taboo. You make it sound as though I violated some oceanic statute
just by bringing it up. I had tried to stress early on that at 23
I'm a bit young, and I realize that, but maybe if you can calmly inform me
of any really horrible no no noooo's then possibly you can just drop
me a note or something? Scolding me publicly is hardly a
conducive way to promote the free flow of information and subject matter
in a board which is not governed by insurance policies nor commercial
institutions.
Furthermore... I think that your view of the future of
submersible use, especially by private contractors, is archaic.
Actually, I might leave the dinosaurs out of it and just leave it at
"outdated". I realize that the older crowed here spent alot of time
either on the surface, or on the bottom, but never in a capacity where a
diver might need to exit the sub at a spot somwehere BETWEEN the surface
and the bottom. I'd imagine that I'm a whole new species of
human who can find extremely usefull ideas for establishing a protocol of
correct procedure and safety for exiting and reentering a sub while in a
column of water, and not grounded at the bottom.
I'm sure there are several possible scenarios for the
situation. I like to think "outside the bun". It's a nasty habit
that tends to get me promotions. The more informed I am
about several ways I can do something, the more contingencies I can come
up with when I need to make decisions. I'm not sure that limiting
myself with conventional taboos is necessary.
We've
been through this. no, No, No, NOOOOOOO!!!!! The boat WILL NOT be
neutral, or even close to it while a diver is outside. Live boating, as
moving the sub while the diver is outside is called, is strictly
forbidden by insurance companies, commerical dive procedures and
common sense. You build the boat to flood negative in excess of
the BOTH diver's weights, as your tender may in fact have to get
out to serve as rescue or back-up diver. Mid-water diving??? Sheesh!
Come on, guys. Vance
-----Original Message-----
From: ShellyDalg@aol.com
To: personal_submersibles@psubs.org
Sent:
Fri, 25 May 2007 12:51 am
Subject: Re: [PSUBS-MAILIST] VBT's
Hi. This is in response to the diver weight compensation
question.
Every dive trip in your sub requires careful measurement of what
you bring on-board.
If the dive plan calls for a diver to exit the sub while at depth,
I would think that it would be better to add buoyancy to cover the
divers extra weight while on-board, and then dump that buoyancy ( air
bubble ) when the diver exits the sub, there-by maintaining neutral
buoyancy while the diver is outside.
When the diver is back on-board, blow the required amount of air
back into the trim tank ( a measured amount of water to compensate for
exactly how much the diver weighs ) and again maintaining neutral
buoyancy.
A sub with a diver lock-out function would need a bigger trim tank
than a sub without that capability.
Don't forget to calculate how much air the diver displaces with his
body, as this will figure into the required additional buoyancy
too.
You don't need a separate pump system, nor would that be desirable,
to let a diver exit and re-enter the sub. The lock-out chamber is
controlled by air pressure, and any small amount of water that remained
within would be easily compensated for by the additional trim tank
volume.
You WILL need some means of dumping the air from the lock-out
chamber once the water is blown out and the hatch is closed so the diver
is once again at one atmosphere. This needs to be monitored
closely so a diver has time to dump the excess nitrogen absorbed by his
body tissues and blood. A diver lock-out chamber is really much like a
de-compression chamber, but is located inside another chamber ( the
sub's pressure hull ) so a compressor to drive out the additional air is
required.
Frank D.
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