Re: [PSUBS-MAILIST] Cement and propane tanks ?

[Ian Roxborough <irox@ix.netcom.com>]

Hi,

from very basic research I've done on this (not with propane tanks)
a potentionally big issue would be shrinkage as the cement sets and
what would it mean for the out hull (an air gap?) and inner hull
(would it get crushed, or an air gap, or nothing?).  Could any gaps
be back filled, and how much would it cost to make sure it's got
no gaps left?

In the end I drew the conclusion that it's probably better to build
a mold for the cement and build a cement only hull rather than
attempting a multi-material hull.  Although I'd be interested in
hearing about any tests if somebody was to persue that method.

Also, cement isn't that much heavier than water, so it won't add
a lot weight itself, that would have to come from lead.

On the subject of multi-material hulls, I do think about steel
and GRP/fiberglass might be worth following up on.  If I ever live
by some deep water and own a boat I would probably try some small
tests samples of GRP steel combo pressure hulls.

Ian.

On Tue, 17 Aug 2004 20:33:02 -0500
"Gregory B. Snyder" <snyder@mnrad.com> wrote:

> Hi guys - 
> I do not recall if this has been discussed before, although I know that
> both of these items have been discussed individually.
> Would it be reasonable to take a large propane tank (outer hull), cut
> off the one end at the curve - insert another propane tank (inner Hull)
> and create a steel/rebar structure to keep it centered in the first
> tank.  Cut the holes and weld in the view ports, conning tower - etc,
> place the through hull connector pipes, then reweld the outer hull cap
> (sealing the outer hull), stand the whole thing on end and fill the gap
> between the two hulls with cement?
> Cement would add the weight, and should be crush resistant.
> Propane tank lovers would get the benefit of saying that they used a
> propane tank, 
> and it might be ultimately cheaper than the other solutions.
> Thoughts on this?
> THanks-
> Greg
>  
> 


-- 



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