From: HUNTR2@aol.com
Reply-To: personal_submersibles@psubs.org
To: personal_submersibles@psubs.org
Subject: [PSUBS-MAILIST] Hard ballast tanks.
Date: Thu, 7 Dec 2006 03:16:41 EST
Hi Kori,
Welcome to the group. I, also live in the "land of fruits and nuts!"
I think you have it understood pretty well. I also want to have the
option
of increasing buoyancy to neutral with a shot of air to purge the hard
trim
ballast tank a little if I take on additional weight. Additional weight
could
be from accidentally letting too much water in the trim ballast or picking
something up with the manipulator arm. If you don't have an air purge
capable
hard trim tank, then the only option is to put some air in the MBT. Once
you do that, neutral buoyancy becomes a challenge if you want to descend
or
ascend very much without surfacing.
Yes, to have larger hard trim ballast tanks is doable, just more structure
and plumbing required. They can be inside or outside the hull. If they
are
inside, they have to handle internal pressure safely. If outside the
hull,
they better be able to withstand the external crush pressure or have
automatic
pressure compensating air available. If a large one crushed at depth, the
results could be scary and perhaps tragic.
It's interesting to note that those with actual pilot experience aren't
saying that large TB tanks are important. Leaving lead at home means you
have a
smaller internal sub to start with and having large trim ballast tanks to
use
when taking passengers just makes the sub larger (greater displacement) to
handle the extra load. The space in the tanks is not functional for
living
or using for anything but buoyancy, weather you are using them or not.
In
effect, what you have done is limit usable internal space in single person
mode
in exchange for not carrying lead. If you're pulling a 5000 lb
submersible,
another 180 lbs of lead isn't too big of a deal. (Less than 1% of the
total weight).
Gene
Central Ca.