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Re: [PSUBS-MAILIST] battery acid? & battery issue follow up



What about scrap iron?
Carl


Dan H. wrote:

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" <coalbunny@vcn.com>
To: <personal_submersibles@psubs.org>
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 smaller 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 lugs 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.







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Spotted Owl...it's what's for dinner.