Re: SAFETY FIRST, SAFETY FIRST, SAFETY FIRST,

[shawl@torchlake.com (Jonathan Shawl)]

Hi all,
Jon Shawl here, Just as a point of reference I am only talking about 1
Atm dry subs.
If others are thinking about a fiberglass wet or semi wet sub or a
pressurized dry sub
then that is a different discussion that I'm not going into.
And please read it all the way to the end. Thanks

> >Jon Shawl....from reading many past postings and some recent ones,
> and from
> >viewing some web pages, that many people are getting way to
> >far into designing a sub without even doing the basic math
> >to get an idea of the pressures and stresses they are dealing
> >with.
>
> Jonathan Wallace.....I don't necessarily agree that "many" people are
> designing
> inappropriate subs, but on the other hand a good dose of safety
> reminding is good to hear from experienced members of the
> group.
>

OK, I admit I don't know the total number of people that are designing
inappropriate subs,
but many subs I personally have seen on the web (drawing board) should
never be built.
or somebody else is going to get killed. I have seen many good designs
also.
I guess it's the ratio of bad versus good designs that scare me.
To me SAFETY should top the list and art should be way down the list.
That's how I see it.

> Quotes of total pressure don't really tell much though, do
> they?  As designers aren't we concerned with quantifying
> effects of pressure by psi and therefore finding materials
> or thickness of material that will resist the pressure of
> water on a per square inch basis?

My point exactly! That is what I was saying if you read the whole
message. The total pressures I listed where meant to prompt some serious
thinking about the awesom forces related to the subject. I have figured
the stresses on my hull with the appropriate hull stress formulas. That
is how I knew what depth my sub was good for. Then I depth tested it to
prove the formulas and the quality of my workmanship. Only then did I
feel comfortable with my design.
If I had designed and built a very good looking fiberglass hull with a
f16 fighter canopy on it for a view port,
I would have to build 2 subs then test one to destruction to get the
max. crush depth. I could not afford to use this method, I'm not rich.
Then use the other one to about 1/5 of that depth just to be safe. With
hand laid fiberglass you have no way to be sure the 2nd one is as strong
as the first. When you are dealing with unusual and untried shapes for
pressure hulls and view ports this is about the only way to do it,
because no one has proven formulas for the one of a kind hulls and
designs I am seeing out there. If you are a large Co. with lot of extra
cash laying around then you could use this method. But, I thought the
general idea of this Psub group was to promote the safe, Personally
affordable, mini subs, that an individual person like myself could use.
Now I'm not claming to be an expert on subs, and I don't have a degree,
but I have valuable experiences and tips to share if people are willing
to listen. I hope the group will not flame me or the other safety
conscious members of the group again. I hear it happened in the past. I
feel the need to scan some photos of something I'm not proud of, my
first mistake in sub building, and add them to my web site so everyone
can see a example of what NOT to do. My mistake was building without
first having all the knowledge I needed, despite the warnings of other
older, wiser, more experienced people. So if you are at the point that
you are searching for that knowledge and you don't have the "I know it
all" attitude then you are on the right track.
No question is a dumb question, if you don't know the answer.
Enough said for now, Jon Shawl