[PSUBS-MAILIST] Vacuum Testing A Pressure Hull

[Brent Hartwig <brenthartwig@hotmail.com>]

Has anyone ever finished a sub hull, and then placed a water fillable boda bag, like used in wake boarding boats to get a bigger wake, inside the hull and filled it until a majority of the internal space was filled (for safety reasons and without the electronics and batteries of course), and then used a high power vacuum pump to test a pressure hull from the inside? Wouldn't such a test put the same basic stresses on the pressure hull as if it was getting hydrostatic or hyperbaric pressure from the outside?
 
I can see that the weight of the water in the bag pressing down on the lower parts of the ribbing might help the ribbing in those areas resist the pressure pulling in on them. I would think you could do a safe vacuum test with out the water as well, if you take the sub out and away from everything and proceed with the test while you are at a safe distance.

Regards,
Brent Hartwig