Re: Cement subs? more to learn

[Axel Iehle <ai@augusta.cma.fr>]

I won't build a cement sub.
For one single reason: I have no time to make
the tests that would bring me to know the subject enough
to rely in the sub I would have built.
Dave  Irons 
thinks cement is great for being cheep, easy and strong?
Good. That may be true. But as it is not proven NOW, as it
may take some time until it is, and as I won't loose time
to work on the question, for me concrete sub is not
what I'm looking for. Even though it may be an elegant idea.

My goal is to build a sub. As soon as possible. I already
consider that building a sub is a serious task, I won't loose
my dream in testing new materials. I'll rather let my
imagination/artistic sense work on the design of the sub.
(Here,
one third of Psub list thinks "Aah... Good. Someone serious here"
one third thinks "Baah... No dreams, no immagination there. Closed to any 
evolution",
and the last third thinks: "He wrote "and the last third thinks: "he wrote 
"and the last third thinks..." :-|   )

I'm not closed to evolution I sincerely hope new material, new research will
facilitate the work of future Psubbers (for short excursions though, I 
personally do not believe in underwater habitat).
I'm not closed to dreams, hopefully I dream a lot. We all do, otherwise we 
wouldn't be on this list, would we? Try to speak with your neighbour about 
building a sub in your garage, you'll see that for the rest of the world:
you're a dreamer (= half-crazy potentially dangerous category!).
But I'm not closed to reality neither: I have no time, no money, and if I put 
some of these two rare elements into building a sub, I'll try not to 
re-discover things that are already known (so I'll get as much information as 
I can) and not to discover things that are not sure (so I'll keep with 
standard ways).

However, I'm interested in this cement-sub thread because I consider it could 
be an easy and cheap way to test a design. Draw your sub, then build it in 
cement (with iron even if it's less strong, it's easier) and test it... in a 
bathtub or swimming pool: you'll know if the rudder is big enough, if you can 
avoid diving plans... things that are highly valuable and difficult to test in 
advance. You may have to re-consider a lot of things. and doing it on the real 
sub could be impossible or too expensive or reduce strength... Then you go for 
the real final design, using the material you want. I don't want (I told you: 
no time) to build many subs. I just want one. So the full-scale cement-model 
may be a way to avoid mistakes. OK, it could be fiberglass but it's more 
expensive.
NB: This test-sub would only be used down to its own height, or so!
Not intended to proceed failure test: I'm speaking of a design test.

Best regards to all,

Axel Iehle