If you understand what you're doing...

[Paolo Velcich <pavel@mail.nauta.it>]

I already apologized in private to the people I may have flamed or insulted (this
was never my intention).

I would like to say my personal opinion - for my last time - about the
"traditional materials versus exotic materials...".

Materials are one part in the manufacturing process (not only in this field) and
there are several factors involved in choosing the right material (for a specific
application).
Strenght, weight, costs, handling, availability, healthy, environmental,
reliability...
Even if an application is very similar to another one, there're factors which
could push the choice to different materials.
What's very important is that the final choice will never result in a faulty
compromise.

When this happen, if in the consumer market, there're minor chances to cause
personal injuries, but there'll good chances to get issued by law.

But in critical environment, like in the air, in transportation and in the water
(both over and underwater), wrong choices usually lead to catastrophic results and
it doesn't matter if the fault involves one single hobbist or more passengers,
it's usually a tragedy and have major undesidered consequences on the entire
community.

this is why we must be very careful and responsible when designing a moving device
(being it a skateboard, a surf, a boat, a bus, an airplane or a psub...).

Somebody on this list stated the better opportunity for the p-subbers to rely on
traditional (consolidated) design and materials instead of dreaming about more
innovative and exotic solutions.

This is a respectable and safe point of view but it doesn't give any specific
contribution for saving lives if it's not linked to a more complete consideration
of the entire process.

A good set of plans (we spoke about Kittredge's) and the right materials
(according to the bill of materials) still miss the manufacturing step (cutting,
forming, assembling, welding, inspecting, testing...).All the above processes
require skills and knowledge.

Are all the p-subbers master welders? Are all of them in full possess of all the
required skills? Probably not. And in this case they will need external support
from "qualified" crafters to get some parts properly done.

Again, are all the p-subbers smart and skilled enough to properly evaluate the job
of a "qualified" craftman?

I think there're so many critical points in the building process that we should
not only focus and fight about the materials issue, which is important but it's
not the only one.

I would say there're several materials and manufacturing process which, if
properly designed and handled, will lead to a successful product.
And I'm pretty sure many more will appear on the scene in the next few years.

But I would also consider this: are all those materials equally available and
feasible for homebuilt psubs? I would say: probably not.

Just to make an example here: composites ( a nice exotic but generic denomination
for a huge amount of different materials) could probably be a possible choice for
a hull.

But, what is a composite? Is it fiber-glass? Is it kevlar(aramidic fiber)? is it
carbon (graphite fiber) or is it any kind of ceramics?... and is it mat, or is it
strand? ... monoaxial, biaxial or triaxial... is it being hand-lay-up laminate?
spray-up..wet lay-up or pre-preg?  wounded , vacuum-bagged ...??? are you using
any core inside? and which is the matrix? polyester.. vinilester.. epoxy...? Are
you using an oven? an autoclave? a controlled environment or is it in your
backyard?
I would be really curious about the wet-out rate, the wet-out and the wet flexural
strenght... could you give an answer?

All the above represent less than 1/100 of the implications of a controlled
composite manufacturing, but this still doesn't mean composites cannot being used
by non-professionals and amateurs. There're amateurs with very good skills and
knowledge and they could probably afford this kind of job.

But it's very difficult to an amateur to get access to reliable and predictable
composite design formulas which would be necessary to build an innovative and
competitive hull.
If you can not calculate the composites to their extreme performances, then you'll
be forced to a conservative design and the final result will be less competitive
then a traditional approach.

Are the composites a wrong materials for building a psub? Not at all, but they
represent a difficult task for the limited resources of an amateur builder.
And the cost factor is a major issue: the advanced composites (needed to obtain
competitive results) are very expensive and the personal use hardly justify the
difference.

Final considerations: what did I demonstrate with this example? I hope I was able
to demonstrate that it's not necessary to say "only mild steel and acrylic are
proper materials for personal submersibles". We can mantain our open minded
attitude and still - honestly - consider pro and cons of alternative solutions up
to find that - if not extremely forced to other solutions - the traditional
options will result to be the most feasible for our goals (history usually
demonstrates the rationality of proven choices but never closes doors).

Personally, I would keep my own freedom to examine the underwater 1atm exploration
world as an open space with chances for motivated innovators to explore new ideas
and procedures, with the necessary responsibility and skills (and resources).

I would also say that, in 1982 I designed my first DPV, an innovative design,
shark-shaped, very hydrodinamic which was designed to fly the water instead of
penetrating it. I didn't build it because the life is not always linear and it
took an intricated path to bring me back (professionally) to my old love.
During the past three years I came back to design underwater devices, but until I
joined this mail-list (even if always attracted by minisubs) i would have never
considered to design and build one by myself. I considered this matter with
religious respect and always admired submarine engineers for their ability to
build these machines.

I still mantains that deserved respect and ammiration, but I discovered a new
world and the opportunity to realize an old dream. I'll approach to this heaven
with the necessary caution, step by step. I must say I partially have in house
(and partially I can access to) the most sophisticated design, analysis and
manufacturing tools but this will never be a substitute to the most important of
the requested skills: experience.

Recently I received Mr. Kittredge's prospect and as soon as I can - maybe the next
year - I'll start seriously approaching this task by purchasing his plans and
building one of his consolidated designs.
By the way I'll continue thinking about flying deep machines and I will try to
find proper answers to some fundamental questions:

Why do I need a mini-sub?
What pushes my interests and motivation along this path?
What am I looking for?
Which kind of mini-sub design would be more suitable to my needs?
How much visibility do I need?
Which kind of instrumentation do I need to implement on it?
How far would I go with it?
Am I going to dive in confined or open water?
Am I going to dive in drifting or calm water?
Which is the max depth of the basin I'll dive over?
Which kind of manufacturing skills do I have?
Which kind of manufacturing and testing facilities do I have/access to?
Which is my budget?

I don't know too much about the humankind evolution, but I give much respect to
the courageous humans and to their curiosity which brought this world to the
current high level of knowledge, I hope such adventurous spirits will continue to
explore our future.

Blue skies and deep blues

Paolo


--
Paolo Velcich
industrial designer

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KORUM DESIGN
Viale Tricesimo 5/6
33100 - UDINE - ITALY
Tel. (+39)0348-2611707
e-mail: pavel@mail.nauta.it
http://nauta.com
http://www.polarexpeditions.org
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