[PSUBS-MAILIST] concrete submarine - i did it back in 1994 - worked perfectly

[diagroto@ibague.cetcol.net.co]

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