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,
You
are correct. Just note however that ABS certification (section 3.5 in
same Underwater Vehicles document) requires a manned test to design depth so
they appear to be stricter than the US Navy
standard.
Jon
On 12/9/2010 11:43 PM, JimToddPsub@aol.com wrote:
Jon,
Correct me if I'm wrong, but I think we're talking
about two different things, one of which I did not reference. I was
referring to sea tests of a manned vessel when I referred to the US
navy standard of 2/3 of design depth.
I think you were referring to the hull pressure test
(unmanned) which often is conducted in a pressure chamber. It's
been a couple of months since I've reviewed that and I'm now a bit fuzzy
on it. At that time I was able to locate several facilities with the
capability to test my hull including measuring compression. I
also took a cursory look at the effect of temperature on the
hull.
Thanks for the
correction.