[PSUBS-MAILIST] Request for pressure factors difference GL/ABS

[Phil Nuytten <72020.572@compuserve.com>]

Hi, Carsten!
        Just a quickie comment on your pressure hull calcs request: Both
ABS and Lloyd's are significantly more stringent at the maximum depths that
you mention ( approx 2000 feet) but less severe than the German rules in
shallower water. For example , Lloyd's calls for; Working depth = 2000 ft  
Test depth = 1.4 X if chamber tested, or 1,3X times if actually tested at
sea. Collapse depth ( what you call 'destroy') = 2X  working depth. ABS is
very close, calling for 1.25X  but making no distinction between chamber
test or sea test - also collapse calculations about the same. There is no
'sliding scale' depending on depth, in either Agency. It would be
interesting to know why a sub rated for, say, 300ft must have a design
collapse of more than twice it's rated depth, while one rated deeper does
not, under the German survey rules . . .the rationale escapes me - but so
does the rationale for Lloyd's requiring a greater equivalent  chamber
pressure than a sea dive. When you ask Lloyds, they smile weakly and say
they "don't know - but that's what it says in the book"!
Phil Nuytten