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

--- Eliezer Rodriguez <eliezer_rodriguez@hotmail.com> wrote:
> Thats really true. Basicly for someone who wants an ambient sub to explore 
> and also don't want to invest too much money in something hi-tech (I refer 
> to deep submersibles), I consider that fiberglass is an option but, always 
> putting safety first. - Cruise on the surface and dive where is not beyond 
> the safety depth.-

But the question was a wood & fiberglass pressure hull, not ambient.  I'm not
engineer enough to comment on that, but I'm plywood boatbuilder enough to know
that such shapes can be formed.  Will they survive, and how deep?  I just don't

If we're back to the geodesic/faceted frame to produce a spherical pressure
vessel, then we're looking at a polyhdron with a hatch in one facet, or more. 
Probably a 20-agon, formed of triangles (I'll spare everyone the geometry). 
The ply triangles could be cut with what sailmakers call "roach" - sides with
convex curve rather than straight sided-triangles.  If tortured (say to a
frame) they'd nicely appoximate a sphere.  Cover same with fiberglass & epoxy
to the needed thickness and away you go.  Needed thickness?  Ask an engineer, I

If the strength of the hull is to come from the glass layup, then the lightest
of ply (1/8", 3mm) can be used to create the spherical form, think of it as a
male mold.  This in turn, being thinner, can be tortured into smaller radii. 
And this makes the woodworking far more powerful, for all kinds of reasons.

If the torturing is too great for the thickness of the ply involved, it is
possible to cut the increasingly non-triangular "triangles" with what tailors
call "darts" - cutouts which when closed and seamed together create 3-D shapes
from 2-D fabrics.  Adds materials, labor, but hardly difficult.  Steel-working
folks will understand the geometry... again it has to do with sheetgoods, not
with the substance of which the sheet is made.  Vacuum-bagging the ply
("cold-molding") is a famous and venerable technique for applying srong, even
pressure to intricately curved plywood, and a sphere is very intricate from
this point of view.  Might not even need a frame, could "stitch & glue" the
"triangles" prior to bagging.

No reason that the above can't be done, perhaps more easily, in a non-sherical
shape - like most subs, I mean.

Certainly testing is critical here.  More than critical, in fact!

If you leave the interior side of the wood unencapsulated, it can be finished
with a deep reddish stain and then spar-varnished to a mirror-like shine, and
the seating upholstered in maroon leather with brass knob-headed nails.  A very
Victorian effect, don't you think?  The viewport could be finished with a
heavily guilded frame... 

-Lew, who was really serious except for the Victorian interior part.

"It's never happened in the World Series competition, and it still hasn't."
             - Yogi Berra

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