Brian,
Back in the 70's many of the manned
submersibles used mercury for longitudinal trim control such as Alvin,
Deep Quest and DeepStar 4000 (pages 91, 113 and 117 in Busby,
respectively). The reason why mercury is so attractive is that it's
dense, with a specific gravity of 13.546 as compared to lead with a SG of 11.34,
and it's easy to pump between tanks located fore and aft. At the time,
most engineers considered mercury to be completely safe. Since then, medical researchers have
found mercury poisoning http://pasture.ecn.purdue.edu/~mercury/src/poison.htm
to be such a medical concern that it?s use is now is banned in most
workplaces. For those trying to
adhere to ABS rules for
submersibles, the use of any mercury in the boat is specifically
prohibited. From as safety
perspective, it just makes good sense to avoid using mercury unless you want to
end up "mad as a hatter"!
Cliff
<----- Original Message -----
Sent: Tuesday, February 17, 2004 8:03
PM
Subject: Re: [PSUBS-MAILIST] battery
acid? & battery issue follow up
Does anybody know where I can get some mercury
?
Brian Cox
----- Original Message -----
Sent: Tuesday, February 17, 2004 3:04
PM
Subject: Re: [PSUBS-MAILIST] battery
acid? & battery issue follow up
I can cast lead.
Carl,
Sand
or gravel is to light for ballast in a sub. It's mass is so much
more
then lead for the same weight that it's impractical in a compact
sub. A
load of gravel in a pickup truck pretty much fills the box. If
it were
lead, it would be a sheet on the bottom of the
floor.
Remember it only the displacement over and above what the same
mass of water
weighs that's effective as ballast.
Dan
H.
----- Original Message -----
From: "Coalbunny"
To:
Sent:
Tuesday, February 17, 2004 5:49 AM
Subject: Re: [PSUBS-MAILIST] battery
acid? & battery issue follow up
> Shawn, that is
something that I have wondered about- will the ballast
> shift? I
have read how a number of scientific units used lead or steel
>
shot. Is there anything that prohibits that being used? IIRC! at
one
> time even mercury was used. Of course we know the
environmental
> implications from that. One thing I thought of using
that should be
> cost effective and would be environmentally
friendly is the use of sand
> or gravel. But since I have no real
unit to use that ballast method
> with, I have no idea if it'll
work.
> Carl
>
>
> NeophyteSG@aol.com
wrote:
> > In a message dated 2/16/04 5:47:29 AM Pacific Standard
Time,
> > Asmyth@changepoint.com writes:
> >
>
> Because Solo is intended as a "flying" sub, it's designed to have
a
> > very small self-righting moment. [snip] If Solo had
conventional
> > stability, she could never roll or fly
inverted.
> >
> > Totally understand. My design is
facing similar constraints except that
> > all my nonessentials
are fared external to the pressure hull which, Sgt.
> >
Pepper-ish, is much smalle! r than yours appears to be. In my case,
I'm
> > juggling axiometric placement of everything in the
horizontal and
> > vertical planes through the hull's
longitudinal axis, leaving the drop
> > weight(s) placement until
near the end to essentially force the righting
> > moment
equations to balance. I also liked the idea of essentially being
>
> able to use just about everything except the pressure hull as a
drop
> > weight should the absolute need arise.
>
>
> > What gave me a worse headache was trying to figure out a
functional
> > ballast system for a craft which will
hypothetically have six degrees of
> > freedom, won't "slosh"
around (changing the center of buoyancy), and
> > will work no
matter what the orientation of the craft ... including
> > upside
down.
> >
> > Given the batteries are snug against the
hull "ceiling", I can't
> > reach the lu! gs to connect the
cables unless they are upside down.
> > Plus, I don't want the
lugs shorting out against the hull. If they
> > cannot go upside
down, I'll probably have to lower everything by
> > about 3".
Plus, all the cables will now be a few inches too short.
>
>
> > Aside from simply not having the room, you're making me
glad that I
> > chose to mount all but the two emergency reserve
batteries outboard ...
> > not meaning to take pleasure from your
pain. :)
> >
> >
> > In a message dated 2/16/04
7:00:24 AM Pacific Standard Time,
> > Asmyth@changepoint.com
writes:
> >
> > The Lifelines can be used in any
position, but only charged upright.
> > The Optimas can be used
or charged in any position at all.
> > Unfortunately, I can't do
a straight replacement because Optima
> > doesn't make a battery
as large as the ones I'm using. So it looks
> > like I need to
modify my hardware and calculations to turn them
> > right side
up
> >
> > FWIW, possible KISS solution: Incorporate a
pivot and latch into the
> > mounting hardware whereby you can
drop them down into an upright
> > position for charging -- when
you won't be occupying that space -- then
> > latch them back
upside down and against the hull during dives. If the
> > current
cabling reaches the lugs in their upside down position, you
> >
won't even have to lengthen them because they'll just need to
rotate
> > 180-degrees. Make sense?
> >
> >
Warm Regards
> > Shawn
> >
> >
> >
*****
> >
> > "Call nothing thy own except thy
soul.
> > Love not what thou art, but only what thou may
become.
> > Do not pursue pleasure, for thou may have the
misfortune to overtake
it...
> >! ; Live in the vision of that
one for whom great deeds are done ..."
> >
> > Man of
LaMancha, D. Wasserman
>
> --
> Spotted Owl...it's
what's for dinner.
>
>
Fact is
stranger than fiction. Truth is stronger than fact. R. Duncan
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