Re: windows

["richard hess" <rohess@hotmail.com>]

>I know that most of you use acrylic for your portholes.  I was 
wondering 
>if anyone has tried using actual glass?  Now, I know that sub windows 
>are not something to skimp on, just to save a couple of bucks!  But I 
>already have a big piece of 1.25 inch glass, and 1 square foot of the 
>same acrylic will cost me 75 clams!  If I had a 10 inch diameter glass 
>window that was 1.25 inch thick, what depth would be safe???
>
>
>                                 Steve McColman, Vancouver Island
>




Steve,

Glass is a dangerous and unpredictable material to use for viewports.  A 
glass viewport is unsafe at any depth, because glass is very susceptible 
to uneven loading under pressure and will fail catastrophically without 
any warning signs.  Glass is not approved as a viewport material by any 
certifying agency.

Acrylic plastic is the only safe material to use for viewports in a 
manned submersible.  I would point you to a book written by Jerry 
Stachiw, "Acrylic Plastic Viewports" I believe is the name of his latest 
book on the subject of acrylic plastic viewports for manned 
submersibles.  Dr. Stachiw has literally written the book on viewports 
and he covers it all.  I have a whole series of his older books and they 
are full of well researched information on viewports, he has tested many 
different designs of viewports to destruction and has developed his 
formulas based on real world testing.  Read this book, it contains all 
the information you will need to design and fabricate acrylic plastic 
viewports for your sub.  

Use your big piece of glass for a coffee table, but use acrylic plastic 
for the viewports in your sub.




Richard Hess

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