[PSUBS-MAILIST] Re: In my search for a simple, cheap pressure hull ...

["Michael B. Holt" <mholt@richmond.edu>]

Jeff Post wrote:
> 
> I think I would nearly impossible to build a practical hull shape using the
> method suggested. It would be very difficult to achieve the roundness
> required for a pressure hull.

I'm not sure it would be as difficult as it might appear.

> If you would like to build a sub from fiberglass, I would suggest using a
> cylindrical object such as a large cardboard tube used in the construction
> industry for pouring concrete pilings. An ideal method would be to build a
> jig to rotate the tube and wind fiberglass saturated with resin on to the
> cylinder.

I think someone has built fiberglass shapes on such a jib. 
I seem to recall it being done for aircraft drop tanks.

Using the metal frames suggested to me is pretty much the
same thing as using a carboard tube.  The facted plywood
hull would have to be put on molds, of course, as would
any boat hull built that way.  Circularity could be obtained
by building a moving jig that would slide along the length
of the hull and circle around the entire thing.  
 
> I think you will find that composites will be expensive for constructing a
> PSub. It really will be much easier and less expensive to buy boiler parts
> and pay for  some metalshop labor as required.

That's pretty much my take on it.  Metal is easier to get,
easier to work with and probably less expensive.  



Mike
> 
> JP
> 
> ----- Original Message -----
> From: Michael B. Holt <mholt@richmond.edu>
> To: PSUBS List <personal_submersibles@psubs.org>
> Sent: Saturday, November 03, 2001 11:29 AM
> Subject: [PSUBS-MAILIST] In my search for a simple, cheap pressure hull ...
> 
> > I went to talk with Dermott, who lives three doors away.  Dermott is
> > assembling parts for a helicopter, and we trade notes on the problems
> > of high-end scavenging for expensive bits of metal.
> >
> > I asked him if he could fabricate for me frames of aluminum (his
> > favorite metal for obvious reasons).  I explained that I wanted
> > to build a faceted plywood hull (like Captain Nemo's Nautilus),
> > and then render it circular by plastering it with fiberglass.
> >
> > Dermott suggested I build the frames out of aluminum, link them
> > with "C-channel" riveted or welded to the frames, and then cover
> > the whole with metal mesh.  Over the metal mesh would go the
> > fiberglass.
> >
> > He warned me that using it might require the use of breathing
> > gear because of the fumes from the chemicals.
> >
> > I think I remember reading about glass-over-metal mesh as a hull
> > material.  I know a small German sub from the 1960s was almost
> > like that.  But does anyone else recall a boat more recently
> > made like this?  Maybe I'm remembering a buoy or something ....
> >
> >
> >
> >
> > Mike