Re: [PSUBS-MAILIST] concrete submarine

[Michael Edwards <me@sustainkauai.org>]

Hello Wilfried:

I do want to pressurize this hull, only with water in it. Less weight to sink
the boat is less weight to pull on a trailer.

I see this as a mobile diving decompression chamber, to maximize my
bottom time. Yes, I do want to come and go out of the sub on the bottom.

No doubt a "normal" wet sub would be easier, I'm just looking for a
way to extend productive time underwater.

Are you saying the 5 cm is the minimum wall thickness  for this type of
construction? If so what size rebar and spacing would you suggest?

Do you have any picture of your small sub?

I'm still wondering how you got such a fair hull, inside and out. I'm guessing
you had a double mold, inside and out? I can't understand you you managed this.
Mudding ferrocement yes, but not as a single cast piece.
Would you share the secret here?

My concern with corrosion is, it seems like concrete fails from the inside
out with the rebar swelling from corrosion. Isn't normal cement hydrophilic?
A poor water barrier?

I'm very comfortable with steel, wood, fiberglass marine construction, but as
you can tell I'm very new to concrete.  I am planning an a much larger boat, but
need to explore this material on a smaller scale to gain confidence and
knowledge.
I believe your concrete pressure hull has tremendous potential.

Thanks for your patience with all these questions.

Best regards

Michael



diagroto@ibague.cetcol.net.co wrote:

> Hello Michael,
> Would not use concrete as material for a wet sub.
> Concrete works fine with wall thickness above 5cm (steel is protected-bringing
> concrete into form is easy) - i would do a nice wet sub (prone position
> floating) with acrylic and glass fiber materials. Or as a steel or alu cage
> with textile coating. (similar to airplanes)
> No need for extra protection of steel in a good built concrete wall. Steel in
> concrete is by far better protected than steel in a steel hull where only
> protection against seawater is paint. Do paint over concrete is dobble save.
>
> Greetings
> Wilfried
>
> Mensaje citado por: Michael Edwards <me@sustainkauai.org>:
>
> > Greetings Wilfried:
> >
> > Thanks for the reply!
> >
> > Yes, I understand the size/weight issues. A am exploring the idea of a
> > pressurized,
> > wet sub.
> > The prone position is very uncomfortable, dry in gravity, but very
> > doable floating.
> >
> > I've spent thousand of hours underwater in this position. I don't need
> > much over 2
> > hours duration.
> > My goal is to keep the trailer weight under 3 tons.
> >
> > Any thoughts about using a high fly ash content to keep sea water out of
> > the
> > concrete,
> > and using galvanized or stainless to deal with corrosion?
> >
> > Best regards
> >
> > Michael
> >
> >
> > diagroto@ibague.cetcol.net.co wrote:
> >
> > > Hello Michael,
> > >
> > > Yes, that is my approach too.
> > > If you did a couple of tanks and test objects for pressure tests you
> > will be
> > > familiar enough with the material to make a sub that works.
> > > My first was very small 2m long 70 cm diameter - 800kg - trailerabel
> > (concrete)
> > > BUT - you need a certain size to be comfortable enough inside to have
> > a several
> > > hours dive. As discussed by carsten it will be hard to combine
> > trailerable
> > > (small and light weight) with comfortable (certain space).
> > > Subs are "heavy machines" by nature (below flotability) this means 1m
> > cubic room
> > > (very little to be comfortable)is 1 ton trailer weight (heavy for
> > trailer).
> > > So i ended up with a 9m 20ton sub comfortable inside, but far from
> > trailerable.
> > > If you need a real trailerable sub you might go for a wet sub only.
> > >
> > > see:
> > > http://imulead.com/sub.html
> > >
> > > Greetings
> > >
> > > Wilfried
> > >
> > > Mensaje citado por: Michael Edwards <me@sustainkauai.org>:
> > >
> > > > Greeting Subers, and hello Wilfried:
> > > >
> > > > I am very interested in concrete submarine technologies.
> > > >
> > > > I retired from 30+ years commercial diving and running ships and
> > now
> > > > live in
> > > > Hawaii.
> > > > Bad for manufacturing but good diving ;-)
> > > >
> > > > I will be using concrete construction for a number of projects at
> > our
> > > > farm, water
> > > > tanks,
> > > > and buildings so why not build a sub?
> > > >
> > > > I am planning first to build a one-man micro sub. It needs to be
> > > > trailerable.
> > > > It would be nice to have something the tiger sharks here can't bite
> > in
> > > > half.
> > > >
> > > > Thanks for hosting this forum!
> > > >
> > > > Best regards
> > > >
> > > > Michael Edwards
> > > >
> > > >
> >