Re: hatch design

[SFreihof <SFreihof@aol.com>]

In a message dated 5/11/98 1:11:22 AM SA Pacific Standard Time,
steve_mccolman@hotmail.com writes:

<< I am building a dry, one person sub that i would like to take to 400 
 feet.  My conning tower is 20 inch dia.  I need to know if it is 
 feasible to use a flat hatch at 400 feet, and if so, how thick it would 
 have to be?      Steve, Vancouver Island
  >>

The pressure increase with depth at about 1/2 psi per foot, so at 400 feet,
you're talking close to 200 psi.  Given the surface area of the hatch, that's
lots of pressure.  If a flat plate can handle it, it would have to be pretty
thick... then the question is, could you lift it to open?