Re: [PSUBS-MAILIST] concrete submarine

[Michael Edwards <me@sustainkauai.org>]

Hello Wilfried:

diagroto@ibague.cetcol.net.co wrote:

> Hello Michael
>
> My experience is that a small sub of 1-2 tons is to heavy to trailer,
> need cranes to bring it to water, need surface ship to bring it to dive place,
> is so uncomfortable that dive time is very limited.

I have a lot of practice with trailering and launch boats in the 2 to 5 ton range.

Although subs would need more water depth to float off the trailer than a regular
boat, I think it might be do-able. As far as to surface ship, here I live, after
launching,
the dive site is less than a mile from the launch ramp. Yes the dive time is
limited,
I am used to limits, as are the batteries and breathing gas. I don't plan on being

in this boat over 3 hours. In my experience, very few good dive sites are close
to a deep water harbor. I trailer able boat with limited range that can get close
to the dive site in the first place has some advantages.

> In a concrete sub it makes little difference if it is 2 tons or 20 tons. (hull
> cost) machine engineering in a 2 ton ship is complicated (all on outside) in 20
> tons easy (all inside - motor, tanks etc. very similar to yacht).
> Once in water 20 tons boat can stay in a normal harbour for years. No crane no
> surface ship. Minimum size is same as you see for autonomous yacht. Can be done
> with some 5 m (complicated) but is nice with some 10m.

We do have a two harbors on this island, on the other side. I would love to make a

larger version, as you have. Ideally it would be diesel/electric with the range to
go 90 miles
between islands. I think we would need to stretch your last boat to about 50 foot
to do this.
I have owned up to 350 tons ships, it takes over your life. A trailerable boat,
and
you can still have your life. Although the big sub is seductive!
Right now, I'm trying to see if this "micro" sub is do-able, or even practical.

> Built the hull standing, from material was wood, the only problem is the cone,
> shape. You can solve it by using a combination of paralel and triangular wood
> pieces in the slip form fixed on their place with wire. The more cone shape the
> more triangular pieces you use. All other is same as normal forming.
>
> Greetings
> Wilfried

Wow, standing up, like 20 some feet in the air? I can see some complications with
a longer boat. You would have to dig a hole to build a big one? Have you thought
of using concrete spheres with a steel hull? Although I can see how much better
it is by keeping it all concrete. Do you have any pictures of the construction
process
or your smaller boat that you would share? I believe last month you said something

about patients? I wish to respect your property information.

I think the major navies would not be happy of a lot of "cheap" submarines.
I love your idea. I believe it is a real technology disrupter ;-)

Best regards, Michael

>
>
> Mensaje citado por: Michael Edwards <me@sustainkauai.org>:
>
> > Hello Wilfried:
> >
> > diagroto@ibague.cetcol.net.co wrote:
> >
> > > Hello Michael, curtis, brian, Gene, Carsten, everyone interested,
> > >
> > > In my opinion to do a sub you can get in and out are two proven
> > concepts.
> > > A simple wet sub at ambient pressure, or a bigger dry sub with diver
> > chamber
> > > like carsten did. Altough i think that anything else is possible i
> > would be
> > > careful not to combine disadvantages of various different and proven
> > concepts.
> > > (water in sub, pressure regulation-complicated, floating regulation,
> > etc.)
> > > Anyhow i agree with carsten that this is a new idea worth to
> > explore.
> > > Would not do it with a concrete hull. (sensible to internal
> > overpressure).
> >
> > Thank you Wilfried, for pointing out the "fatal flaw". You were clear in
> > your
> > earlier threads
> > that concrete shines in compression, not with pressurization. I guess I
> > presumed
> > that like water tanks, the material could stand a certain amount of
> > pressurization/
> > tension?
> >
> > > You also should be aware that there is a BIG difference between
> > ferrocement
> > > construction (meshing glue cement in...) and massive concrete
> > construction.
> > > Ferrocement is a concept that is used in yacht building only (not
> > other
> > > engineering ) had a LOT of problems especially rusting of mashing and
> > crackling
> > > due to not optimal use of concrete and lack of proper compactation. It
> > also is
> > > specially problematic for small yachts below 10m due to thin walls
> > while it can
> > > be used with relative good results for bigger yachts.
> > > Massive concrete is widly used in submarine tunnels (salt water under
> > pressure)
> > > in drilling platforms (wave action) and offshore oil tanks and dam
> > building in
> > > same or more severe conditions than it would be in a sub.
> > > In all this conditions concrete is compacted as in normal construction
> > what
> > > limits it to walls of 5cm minimum. - You need 2cm of concrete above
> > steelbars
> > > as minimum to avoid rust and distribute forces. You need space in your
> > mold to
> > > bring concrete in and compact it properly.
> > > I had a double mold (kind of gliding mold as used for television
> > towers or
> > > bridges, boat consists in cone shape rings with variable diameters -
> > no secret)
> > > This means i did a cone shape ring every week and form was made to be
> > recycled
> > > and to adapt to any ring diameter and wall thickness on both ends.
> >
> > I have a million questions here. How many days did this "pour" take?
> > Were the cones added on to an "internal" male mold? Or were cones
> > used for both the inner and outer forms? Was the hull formed on it's
> > side or standing upright? What material did you make the forms out of?
> > I have seen slip forms in cast buildings but nothing anywhere near
> > this
> > complex of a form in concrete.
> >
> > > You are completly right, if you do not compact your concret properly
> > during
> > > construction (as in many ferrocement constructions) you will have a
> > poor
> > > crackling water barrier, endless rusting of steelbars - final failure.
> > If you
> > > do it right you will have your steel completly protected (2cm below
> > surface).
> > > Every building material has its limitations. And one of the
> > limitations of
> > > concrete is wall thickness below 5cm. This makes it little ideal for
> > small
> > > trailerable wet sub. But it can be used with excellent results for
> > bigger thick
> > > wall pressure standing dry sub.
> > > Greetings
> > > Wilfried
> >
> > Wilfried; do you feel in retrospect, that the small 2 meter sub was the
> > wrong
> > material
> > for this small size? As a practical matter, what is the minimum size
> > you
> > would recommend for a "dry" concrete sub?
> >
> > Thank you
> >
> > Michael
> >