Re: Making viewports (was: Visibility / Safety or Safety / Visibility ?)

[Phil Nuytten <72020.572@compuserve.com>]

Hi, John!
        Nope, acrylic hemis are a poor trade-off ( depth versus weight)  -
depths past a few thousand feet will see increasing use of glass and then .
.  transparent ceramic.  Dont rule out the old conicals, tho' - we have a
really cool design for a 20,000 foot conical  port that is 6 feet at it's
major diameter and 3 feet at the minor . . .and it was designed by the
foremost submarine acrylic authority  in the world!!  Angle? . . .that's
what we paid a bunch of $$ to learn!! (G)

Regards
Phil Nuytten