Did I say that????

[shawl@torchlake.com (Jonathan Shawl)]

Phil Nuytten wrote:

> J. Shawl's comments ( where Mr Shawl appeared to be implying that there
> were some parties advocating research/'odd' materials/innovative design
> etc. -  over safety):

I agree with what you say I said, but I don't think I said that exactly.

> Mr. Shawl says > "it is discouraging to me personally when some-one goes
> and says you can build a sub out of anything that keeps out water"

Did I say that????? Nope, not me. All I could find was " I'm getting a little
frustrated." kind of the same?
But again I agree.

>  Well.goodness gracious . . of course you can!! That statement was not meant
> as
> my opinion - it is a simple statement of fact! You could make a perfectly
> adequate submarine ( "sub" ="under/below" and "marine'"="the ocean/sea")
> out of rubber

I like facts! I always tell my wife I'm not arguing, I'm stating the facts.;-)
But why bother, sometimes a fact is useless?
It's like saying, "I can eat anything as long I know all about the material and
how much it takes to kill me. Lets all talk about it and explore the possible
outcome"

> - it was not my intent to discourage any-one - only to open up some of
> those possibilities for discussion . . .which I assumed was one of the
> major reasons for having a forum of this nature.

I still think it would be better for us to try to narrow the scope of
possibilities and home in on a good sub design or good sub design philosophies
and formulas. And present some examples of what is a sound design and contrast
it with bad designs and show why from a scientific point of view.

>          A  major problem with getting too specific in the subject of
> material selection/suitability/depth is that it requires a precise set of
> parameters or definitions to be known, or agreed to, by all participants.
> For example . .we talk about "mild steel" as a common sub material - what
> we really should be saying (instead of 'mild') is : a steel with a yield
> stress ( in Ksi) of 36.0000 Ksi -  a Young's modulus ( in Mpsi) of  30.0000
> Mpsi - a Poisson ratio of  0.3000 - a density ( in lbs/cu in) of  0.2830
> lbs/ cu in . We would then need to define, specifically,  what structure we
> are talking about . . .say, a cylinder with 'adequately' capped ends , size
> . .36 inches ID X 36.5 inches OD ( wall thickness= 0.2500 in ) X 60 inches
> OA cylinder length ( disregarding heads).  If you asked a designer about
> this configuration, the designer  could say " Sure, it will go into a
> thin-wall collapse mode  at 0.1573 Ksi external pressure or a depth of
> about 350 feet - and, using the 2:1 design collapse/safe working depth
> ratio required by most  certifying agencies ( Lloyds/DNV/ABS etc.,) that
> would give it a safe working depth of 175 feet.  It will weigh 483 lbs in
> air and have a bouyancy of  1841 lbs. I could give you the specific Delta
> stress for delta I D/ delta O D/ and delta length . . an so on"
>         The above is not to be smart nor patronising - it is the most
> basic info required to make the most basic  calculation of safe depth . .
> .NOW comes the harder stuff - you say you want to cut a hole in the centre
> of this cylinder so you can get in? well, how do you propose to restore the
> strength and intregrity  of the cylinder?- doubler plate? ring? You get the
> idea. I'm sure.

I agree with that. I think that is the kind of detail most of us want to get
into, or learn about.

>         Some of the subbers who have built their own subs can tell others
> how they did it . .what specific hull materials/dimensions/geometry worked
> for them . . . and most seem quite willing to do so.

True, so far.

>  Some seem to indicate that they have arrived at sacred grail through a
> torturous and
> dangerous maze and tell others that they, too, must travel  that trail and
> should listen well to avoid pitfalls. Nonsense.

Nonsense is right, where did that come from. I hope you are not referring to me
again, As I don't feel that way.I hope I'm not coming across like that. But
what is wrong with learning what not to do from others "pitfalls" I.E.
mistakes?
It could save a person a lot of time and trouble.

And Phil thanks for the book titles. I think that is the kind of info that is
needed!
I agree with the rest of what you said.
Jon Shawl