Re: Viewports

[Subscuba@aol.com]

Mr. Boucher,

This is to answer your concern about someone using 0.25 inch thick viewing
ports on a 1 Atmosphere Sub. You have a good point, in a word, don't do it!

My Sub is a wet Sub as I have said many times. A port of 0.25 inch thickness
is fine. There is no differential pressure across the port. Thus 0.25 is fine!
Especially if the material is polycarbonate which is stronger than acrylic
plastic. The human powered Subs also use 0.125 thick viewing ports but the
most common is 0.25 thick.

For ports that have to withstand external pressure, the net weight and force
is many times higher than that required for a wet Sub and my discussion does
not apply to 1 Atmosphere Subs. 

Thus, I do recommend a thickness of 0.25 for a wet Sub that has no
differential pressure across the port. I hope this is clear, perhaps I should
underline and make bold the term "Wet Sub" for those that don't understand the
term. I do make the assumption that what a Wet Sub is is widely understood. It
should be obvious that 0.25 inch thick ports for a 1 Atmosphere Sub would be
dangerous. Ray's paper on plastic forming is still valid.

Have Fun,

Ken

PS Sorry if I confused you or anyone else out there.