Re: Chiseled in Stone (Or Concrete)...

[protek@shreve.net]

Rick,
    Good to have a good-natured exchange of ideas here...

[I wrote]
>> How are you going to be sure that
>> you have all the air bubbles out of the mold?  What happens if you do
>> have an air bubble?  Plaster over it?  What about inside the hull wall
>> itself?  X-ray it?
>

[Rick wrote]
>Industrial concrete vibrators do a good job of reducing bubbles.  Of
course, mixing
>the concrete properly is primary to cement/water ratios.  I believe it was
Dave Irons
>who had mentioned that voids can be filled by injecting with polymer.

Well, since the sub is not a vertical concrete columb but rather laid
horizontally in the pouring process, it may be physically impossible to
remove bubbles without tilting the sub up and down while vibrating.

>I had proposed using cedar (for the beauty) as a deck and hull material
epoxied over
>marine ply decking for a wet or ambient boat only.  It's a proven
technique for
>conventional wooden boats.  An ambient sub is certainly nothing too much
more complex
>than a boat with a hole in it.  That's why conventional boat building
techniques can
>work so well with this type of sub.
>

>> [snip]        I think that the main reason people want to try different
materials
>> is that they do not feel comfortable welding or don't really know
>> how.
>
>That was certainly my reason for choosing other materials.  I've worked with
>concrete, wood and fiberglass. Even knowing what I do about one-atm. hull
>construction, I still feel more comfortable with a dry ambient.
>
There is welding, and then there is "Welding".  There are welds on a psub
that are not life critical.  There are other welds that definitely are life
critical.  The pressure bearing welds need to be of the utmost quality.
How about this thought; if you assembled the major hull materials, and cut
and grind them into the proper shapes for welding, and then hired a
qualified professional to do the welding, it could be done in fairly short
order.  That is, once again, if everything were already prepared and ready
for placement.  If a person can not use a grinder, he (or she, to be
proper) shouldn't try to build any form of sub.  

Once again, as I have said many times, all of this should be supervised by
a qualified professional engineer for safety sake.  I doubt that there are
many professional engineers that would sign off on concrete for a sub.  I
know a prof at Louisiana Tech that is in the Civil Engineering section.  I
would love to hear what this P.E. would say about this issue.  I think if
any engineer would support the concept it would be a civil engineer.  

Rick, you know the main difference between a civil engineer, and either an
electrical or mechanical engineer?  The latter two often build weapons
systems.  The civil engineer builds targets...

Gary Boucher