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Scott, there's also a highway in Kansas that will get you to the Texas
coast in about 13 hours of road time.
JT
In a message dated 12/11/2010 5:43:25 P.M. Central Standard Time,
muddywatersfarm@hotmail.com writes:
Hey,
there is a lake that is 60 feet deep in Kansas Jon.
hahaha
-Scott Waters
Date: Sat, 11 Dec 2010 13:57:12 -0500
From: jonw@psubs.org
To:
personal_submersibles@psubs.org
Subject: Re: [PSUBS-MAILIST] Design
depth
Alan,
The definition
for rated depth doesn't include any wording for a 1.25x safety margin.
It is nothing more than the depth to which the vessel has been operationally
tested. Absent a test chamber, the only way for a home-builder to "rate"
their sub is to test dive it to some depth. However, that depth may be
significantly less than either the failure depth or predicted maximum
operating depth. For illustration, imagine the owner of a K350 who lives
in Kansas where the deepest lake is no more than 50 feet. If they go to
30 feet the first time they dive their sub, then that sub is only rated to 30
feet even though it is a K350. If they go to 50 feet the second time
they dive the sub, then that sub is now rated for 50 feet. Assuming they
never travel out of Kansas that sub will never be rated for more than 50
feet. It doesn't mean the sub can't go to 350 feet, it only means it
hasn't. In this specific example I don't think adding a safety margin
(1.25x) makes sense, and by definition its not required. See ABS
Underwater Vehicles Section 3.5 for a good example of how rated depth is
used. As I understand the ABS rules, rated depth is equivalent to saying
"What's the maximum depth this sub has been operated at?".
Associating
design depth with operating depth (maximum or not) doesn't make sense to me,
but I guess I'll have to live with it. We then need to include "failure
depth" as a definition to our guidelines.
Jon
On 12/11/2010
12:30 PM, Alan James wrote:
Jon.
A bit of nit picking here but it seems the
"rated depth" is the test depth devided by 1.25 (for ABS).
Or the same as your maximum operating
depth.(design depth) & "Not" the deepest depth the vessel has been
tested to.
ABS Rules for Building and Classing Underwater Vehicles, Section 3.3.1,
requires a hydrostatic test "to a pressure equivalent to a depth of 1.25
times the design depth for two cycles."
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.
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."
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