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Re: [PSUBS-MAILIST] Concrete submarines
Juergen,
Do a search in the psub archives under "concrete submarines". It would be best to use SR cement ( sulfate resistant) if you're planning on taking it in the ocean. Below I have copied a old post about concrete subs from Wilfried Ellmer. There is some information on his sub in Colin Brooks new addition of his Ferro-cement Boats book, but the book is mainly concerned with "ferro cement" construction which is different than how you would construct a sub for pressure. link: http://www.ferroboats.com/
Brian Cox
--------------------------------------------------------------------------------------------------------------------
Hello,
I am Wilfried Ellmer and i recently did a search engine search on my name and
found it connected to a discussion on this board about concrete submarine
hulls.
This explains why i answer now to a discussion that took place here some 3
years ago.
One of the questions asked was "did everyone a hull or sub like this" .
Yes i did one (in 1994) it was: 9 m long 2.5 meter diameter 18cm wall
thickness, form of a blimp 15 tons wihtout ballast 20tons with ballast.
I also did earlier a smaller hull of 2m long and 0.7 m diameter to test the
concept.
Both hulls where converted in fully functioal subs and i personally had a lot
of dives and fun in those two subs.
Fact that i am still writing proves the validity of concept.
Unfortunatly the concept was so new back in 1994 that i could not find anyone
interested to discuss or make a projekt with me.
So let me answer from practikal point of view some questions that came up here:
Can you transport a hull like this?
Yes i transported the 9m hull on a truck from innsbruck where i built it to
lake Atter where i dived with it (some 5 hours) did not break, not leak, no
damage.
it was stapled on wood - no special transport thing - impacts that occur on a
truck will not affect a hull like this.
Will it crack when you hammer on it ?
This hull had a 18 cm thick concrete walls curved in 3 dimensions - and
reinforced by 5mm steel bar net all 5 cm - this is similar to a bunker wall,
or to a bridge - if you hammer it will it break ? - of course not.
Will it stand hydrostatic pressure ?
Just think of hoover dam, or submarine tunnels, or oil drilling platforms, -
is concrete standing hydrostatic pressure ? - of course for many decades
without any notable change.
Do you need non steel reinforcement?
- no in a 5cm or more thickness concret wall steel bars are perfectly
protected.
Will it stand changing load from waves ?
Is concret standing changing load on bridges - of course ! - and in by far
more sever conditions. Or in buildings under erver changing wind pressure.
Is building the hull a tecnical problem ?
handling a 18cm thick ship hull is always a problem - just imagine welding
steel plates of 18cm !!! - or forming them as a sphere or streamlined blimp.
(with 3 dimensional curves). I could do it in a backyard with concrete,
(without having bubbles and having reinforcement where it belongs) - i doubt
that i could weld or form 18cm steel plates or alu in a backyard.
This is a task that is only (if ever) handled in battleship construction.
What you can do with concrete is incredible strong thick walls on relative
small subs - this has nothing to do with ferrocemnt as used in yachting (iron
mashing and plastering on) - this is forming concrete in the way as it is used
in tunnels or in radio towers with continous forming that makes a little part
every day.
Had patented some of this stuff...
Do you need a special covering - double hull etc:
No - just use what is proved in tunnel or dam building it will work excellent
in hydrostatic pressure for decades as it does in dams and tunnels.
Do it only work for big subs ?
No - had done 2m sub with 5cm wall thickness and 9m sub with 18cm wall
thickness both worked excellent.
How can you test concrete ?
How do they test dams or bridges or tunnels - x raying every cm? , by using
paleontolgy equipment? (as a discussion suggests) ?
I had a practical approach deep test at 150m (was deepest site i could find in
the lake) and considered it save therefore to dive with 50m.
If you get obvious material changes over time (rusting of steel reinforcement)
visible (new) cracks etc...yust do pressure test again and keep it 1/3 in
normal use this should be save.
(by the way...did not get any rusting, or cracks during 15 years of use) - So
is it done in dams, bridges, pressure vessels, concrete pressure hulls of
nuclear plants etc. - periodic testing with overload - new testing if doubths
about structural integrity come up at visual inspection.
No need to predict destruction depth exactly with complicated
methodes...doesn't work anyhow - not even for navy steel hulls - as example of
treasure accident shows.
A wall thickness of 18cm on a 9m boat gives you a calculated destruction depth
far below 1000m (normal concrete without any special) you can keep it so far
above that in normal dive operations that it will be save - no matter - if
anything like bubbles or cracks gives you a little additional weakness.
All concrete on all dams, tunnels buildings, drill islands etc. have bubbles
and cracks - do they collaps ? - of course not!
What is the real problem of constructing a sub or habitat with concrete ?
Shipyards are not familiar with this material, and those who are familiar with
it (tunnel engineers) do not build ships or subs.
Are there unsolved problems?
All problems are solved for decades all is available but nobody applies it on
subs.
I did it - it worked excellent - had a lot of fun -
If anyone wants to discuss or suggest me a project...please go on.
Wilfried Ellmer
----- Original Message -----
From: "Juergen Guerrero Kommritz" <groplias2@yahoo.com>
To: <personal_submersibles@psubs.org>
Sent: Thursday, June 16, 2005 4:42 AM
Subject: [PSUBS-MAILIST] Concrete submarines
> Hello Psubbers
> I am searching some information about concrete for
> submarine hulls. I know at least one submarine was
> build with concreteand there were some other projects
> on the work.
> I want to know if the it is possible to use "normal"
> portland concrete for the hull I dont´t know if this
> will be enought (water thigth)and it is impermeable
> or if it is better to use an special sealling product
> for the outer coating layer.
> May be it is better to use a sealling product in all
> the concrete mixture?
> I only have little experience with concrete (only
> portland) building bricks and a small water tank that
> was not very impermeable.
> I thank you for any information
> Best wishes
> Jürgen
>
>
>
>
>
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