Re: [PSUBS-MAILIST] Viewport Toughness

[dinosnider666@spacemail.com]

What about using hot/cold expand differences, mate 2 plastic layers - and have the inside one exerting a push outwards at ambient temperatures? Essentially, the water begins to push and has to offset this 'negative pressure' prior to working against the basic structural strength. Works well with 2-layer tubes. I'm intrigued by getting ahold of a lathe and mating 2 pipes, maybe of different layers together. Thought not so much an issue, given need for ballast, unless very deep diving.

Found interesting reference to differnce in compression under pressure of water and steel, with implications for variables depths.  Guess first deepdiving ?bathysphere? used gasoline's compression for something like this.
D