Hi TC,
I think the reason people don't design for
shallower depth is because
if you are going to the bother of making a
pressure resistant hull for a 1atm
its not much more trouble to
go a bit thicker with the metal & hence deeper.
Given the overall
cost of building a sub, going a bit thicker in the metal is
a
comparably small amount.
There is an article on fiberglass in the
frequently asked questions on the Psub site.
As said previous,
you've got to go a lot thicker with fiberglass than metal &
hence
the subs displacement is more & you end up heavier, also its
a lot more expensive
& you really have to know what you are
doing when laying it up.
Fiberglass has strong characteristics in
tension but not in compresion, & is only strong
in the
direction of the fibers.
Maybe fiberglass on a small sub but the size
you are talking about would be a huge cost.
Then you have to buy
extra lead to sink as you don't have the inherent heavyness of
steel.
Regards Alan
----- Original Message ----- From: "T.C."
<
tc.craig@gmail.com>
To: <
personal_submersibles@psubs.org>
Cc: <
personal_submersibles@psubs.org>
Sent: Saturday,
September 19, 2009 12:31 PM
Subject: Re: [PSUBS-MAILIST] Hello; Design;
Materials; Thanks
Dear Sirs;
First, let me thank
everyone for the thoughtful and detailed
responses. You've given me a
wealth of information. Thank you.
After digesting these
responses, and reading my original post, it has
become obviouse that I
failed to clearly communicate my design and its
intentions as well as
the quality of my previous research.
I guess this is what you get
when you assume engineers will read
between the lines...:)
1.
This will be a 1 atmosphere submarine. I will consider an
ambient
if the operational design makes more 'sense'.
2.
25' in length (pressure hull)
6.5' in r^2
2.5-4'
draught when surfaced. Though clearly this is volume/
displacment
dependent.
3. Operational depth 20' - 50' with excursions into 60'.
Crush depth
at 90' -100'. Most operations will be I'm a total
atmospheric pressure
of 1.5 - 3.
I
Might also consider a
shallower crush depth and operate in 1-2 ATM
waters.
My
point in mentioning WWI designs, monitors, and David boats was
to
communicate the spirit of the design.
I'm aware that David
boats "smack" of drug running craft. So do single
engine Cessnas and
go-fast speed boats, but that doesn't mean I
wouldn't become a pilot,
or built a boat at 80mph.
I will not comprise my design for a
losing war on drugs. I will
declare my flag (US), and allow them
to board. But what I will not do,
is sacrice the legitimate freedom to
design a boat of my choosing.
Motorcycles are tough to see. So,
like a motorcyle, I will attempt to
make myself as "bright" as
possible. Though I do hear the all or
nothing surface argument,
and it makes good sense.
My goal is light "cruising" capability and
mostly on the surface. My
operations will be resticted to navigatable
waterways, bays, and to
near coastal operations.
Finally, I
appreciate the hull calculators and the ambient facts,
these will not
go to waste. I am still considering fiberglass for
inland work. Ive
thought about designing to 250' and if the economics
make sense, I
might do that.
Basiclly, I wanted to get a better grasp of the full
materials at my
disposal given the pressures I'd be
facing.
Steve, I don't know why people aren't designing for
shallower depths.
It seems more accesable using cheaper materials and
decent integrity
given it's operational range.
Sent from my
iPhone
On Sep 18, 2009, ts at 12:57 PM, Ray Keefer <
psubs2001@yahoo.com>
wrote: