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Joe,
The bouyancy of all your 1 atm
structures is what provides the ability of the sub to float with everything else
attached. In other words, for eg, if your displacement of all your 1 atm
compartments was 6000 lbs, then the TOTAL weight (including fairing, motors,
etc, etc, etc, as well as the actual pressure hull itself) must weigh 6000
lbs. If all your fairing weighs, say, 1000lbs, then that has to be
subtracted from the 6000lb total, leaving you 5000 lbs for everything else and
so on. If at the end of adding up the weight of everything you are too
heavy, then your sub will sink and you will have to lighten it up OR add to it's
displacement. If after adding everything up, you are too light, your sub
will float = boat. The way I am approaching it is I am aiming to have the
weight come in under the displacement. I will make up the difference in
weight by adding weight to the keel until it = the displacement.
Myles.
----- Original Message -----
Sent: Wednesday, November 16, 2005 11:24
AM
Subject: [PSUBS-MAILIST] Free Flooding
Spaces
Paul & Dan (ref: your reponses below)
I need to cut total interior floodable space by at least half. What
everyone's been telling me has sunk in, the numbers aren't lying. Myles
was correct, it's either a sub or a glass bottom boat.
If one where to consider the free flooding fairing idea more closely, how
do you provide sufficient surface buoyancy for the structure without running
into the same problems all over again?
These WWII boats do not "scale' down well and a short and stubby
"caricature" shape would actually be easier to control. Damn problems keep
rearing their ugly little heads!
Joe
From: Paul Kreemer
<paulkreemer@gmail.com>
Reply-To: personal_submersibles@psubs.org
To: personal_submersibles@psubs.org
Subject: Re:
[PSUBS-MAILIST] "Frankenboot"
Date: Mon, 14 Nov 2005
11:46:06 -0800
Joe, just writing to put in a plug for Dan's suggestion: that
you first
consider the displacement of your minimally sized dry compartment
and
then treat the rest of the vessel as a fairing. The fairing
would
add some displacement, especially being built of plywood but
you'd have
to get the whole thing into your target displacement. The
first
step would be to choose your desired dry weight and/or crew
compartment
volume. (10,000lb? which is almost 160cf.)
You could add in your maybe 30% reserve buoyancy (48cf) for good
surface operation but those are just variable ballast tanks,
mostly for
surface use and emergency surfacing, right? They wouldn't
add to
the displacement of the boat and the whole thing really would
weigh
10,000lb on a trailer.
This seems like a better way to describe a WWII-style homebuilt
that
will be good on the surface - a modest pressure compartment with
a big
free-flooding fairing. You could do a big deck and
superstructure
like on that nice S-44 replica, but you would need some
propulsion
power to move such a rig submerged!
Please correct me if I'm wrong on this - certainly there are
different ways to approach the design process.
Paul
-----------------------------------------------------
-----------------------------------------------------
Dan H. wrote:
Maybe
your only planning to build a small pressure hull with a
big fairing
for your subs appearance. If so, then your displacement is
only your
pressure hull and the fairing can be free flooding and not part
of your
displacement equation at all.
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