RE: [PSUBS-MAILIST] Prestressed concrete pipe

["Brian Cox" <ojaivalleybeefarm@dslextreme.com>]

I'm a ferro cement junkie !  It's been a fun experiance doing this project
so far.  For me it allowed me to work on it at very little out of pocket
cost, however quite a bit of time.  If you had a crew of workers working
everyday you could finish it in no time at all.  I like the ability to be
able to drill through it and attach hardware to it.  With the exoxy coating
it will look like it is made out of fiberglass when it's done.

Brian

-----Original Message-----
From: owner-personal_submersibles@psubs.org
[mailto:owner-personal_submersibles@psubs.org]On Behalf Of Marc de
Piolenc
Sent: Wednesday, March 17, 2010 9:21 AM
To: personal_submersibles@psubs.org
Subject: Re: [PSUBS-MAILIST] Prestressed concrete pipe


I love ferrocement for its chief quality, which is the ability to form a
very stiff and strong structure that is also very thin.

Unfortunately, the more I study submarines the less I like ferro for the
pressure hull. In compressively loaded structures, which fail due to
structural instability rather than by crushing the material, thickness
is a virtue because it resists buckling, so thin ferro is not
attractive. And it's hard to make ferro thick (without building in
voids) except by Iorn's lamination process, and that is slowwww.

So for the pressure hull, prestressed concrete starts to look rather
good. Now for the outer casing that holds the main ballast tanks and
other stuff and needs to have a fair hydrodynamic shape, ferro still
looks very good. The pressure hull can be an ugly cylinder - nobody
needs to see it. It just needs to be strong and keep the crew alive.

As for joining sections together, that's the next topic I need to
research. There must be a way.


Best,
Marc

On 3/17/2010 11:24 PM, Brian Cox wrote:
> Marc,
>         If you could figure out a system for connecting them and making
end
> caps you would have an instant submarine!  It could be done, but why?
The
> reasoning behind my ferro hull is that I was able to make a freeform shape
> which is hydrodynamically advantages.  My shape also doubles as a ballast
> and a structure to carry the actual pressure hull (which is steel).  So
mine
> is sort of a hybrid.  In my sub the wieght of the ferro cement will
> contribute to the wieght I will need anyway so I figured that would help
me
> in that regard.  But working with the concrete is very interesting,  I had
> some minor damage to the egdes of my ferro structure when I had to flip it
> over using the fork lift  - to repair it all I had to do was mix up a
small
> batch of my cement mix and it was like new!  I'm looking forward to
epoxying
> the whole thing and adding some color !!
>



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603-529-1100
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