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Jon, Alan, et al,
I think there is some inconsistency in definitions
due to the different sources. ABS defines Design Depth
as:
"The depth in meters (feet) of water (seawater or fresh water) equivalent
to the maximum pressure for which the underwater unit is designed and approved
to operate, measured to the lowest part of the unit."
That sounds a lot like operating
depth, but still leaves me with some questions as to exactly
what they mean. I could take that to refer to either the 300' or the 600'
in my example, but it seems to make more sense for it to be referring to the 300
feet. I have understood the Design Depth in navy terms to mean the maximum
depth which the hull could withstand with only a slight margin before
failure.
ABS defines Rated Depth as:
"The depth in meters or feet of water (seawater or fresh water) equivalent
to the pressure for which the underwater unit has been operationally tested in
the presence of the Surveyor, measured to the lowest part of the unit. The rated
depth may not exceed the design depth." Note the last
sentence.
I think it would be good to get ALL the depth definitions very
clear according to ABS and cease any reference to navy standards since the same
term could mean very different things depending on whose definition is being
alluded to. It's not something that is going to be sufficiently addressed
tonight. Let's take time to get it right and contact whomever we might
need to if that should become necessary in order to understand each of the
terms being used to define the subject term.
Section 3.1 ABS states:
After out-of-roundness measurements have been taken, all
externally-pressurized pressure hulls are to be externally hydrostatically proof
tested in the presence of the Surveyor to a pressure equivalent to a depth of
1.25 times the design depth for two cycles. Pressure hulls designed for both
internal and external pressure are also to be subjected to an internal
hydrostatic pressure test in accordance with Part 4, Chapter 4 of the Steel
Vessel Rules. Acrylic components are to be tested in accordance with Section 7
of these Rules.
Until later,
Jim
In a message dated 12/9/2010 10:50:48 P.M. Central Standard Time,
jonw@psubs.org writes:
Jim, |