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Rich,
I am forwarding the response Jack Kellon has made to your e-mail to Dan
Volker of 8 Feb 96. This is becoming a constructive discussion, in part,
thanks to you.--- Dave
10 Feb 1996
To: Richard Pyle
From: Jack Kellon
Please note that the statement in #3 was SOME manufacturers. Nevertheless,
I am only aware of one electronically controlled unit that used a single
sensor and non-polling circuitry, the Westinghouse CCM. I first saw this
unit around 1970 but never swam it. I know that at least one NEDU
evaluation report was published on the CCM and it was part of a U.S. Navy
"swimoff" at Roosevelt Roads. I don't think it ever made it to production.
If you are aware of others, I would very much appreciate any information
you could provide on them. I could also use some enlightenment as to what
electronic closed circuit rebreathers don't rely on some type of circuitry
or electrical device to function.
RBC doesn't recommend bailout procedures other than to state that all
bailouts should be to a separate open circuit source that includes whatever
redundancies are considered desirable for the depth or environment in open
circuit technical or "extended range" diving. There are so many variables
to be considered that I am leery of the liability associated with
misconstruing more detailed procedures. I'm often asked how long a cave or
pipe penetration can be made with our units, and my stock answer is that
you should not get into ANY situation with a rebreather that you can't
recover from with a separate open circuit bailout ON YOUR PERSON. You
shouldn't count on being able to reach another diver or the last staged
tank(s) should you have a total system failure on the rebreather, such as a
breathing loop breach.
You are 100% correct in stating that divers will die using rebreathers and
most of them will die because of user error. In over 30 years of rebreather
use, including several hundred hours on electronic sensor polling units, I
have had three associates die on rebreathers. In one case, there was
absolutely nothing wrong with the closed circuit mixed gas electronic unit
involved. The diver simply ignored the alarms when the oxygen supply was
depleted, probably because of task overload. In the other two cases, the
units failed and the divers were apparently not able to rectify the
situation, even though they had been trained to do so. It has been
suggested that too much time had elapsed since training without adequate
emergency action drill reinforcement. I know at least three people that
would agree with that assessment as a more widespread problem: Dr. Morgan
Wells, Tom Mount and Hal Watts. I do not know Dr. Egstrom personally, but I
know that he has long been an advocate of periodic knowledge and skill
reinforcement. This is an important issue for rebreather divers that has
yet to be addressed by any manufacurers or training agencies that I am
aware of.
I have had seven personal close calls with rebreathers. Six were on various
electronic units, two as result of simple electronic failures and four as a
result of electronic failures due to water intrusion. The seventh was on a
Drager FGG III and was caused by a temporary bout with that most deaded of
diver diseases, terminal dumbass. Common sense no ka oi.
Mahalo and aloha,
Jack
xxxxxxxxxxxxxxxxxxxxxxxxxxxxx
Dave Schubert
Instructor Trainer: PADI, IANTD, DAN
Photo...Video...Rebreathers
1201 N. Ocean Drive
Singer Island, FL. 33404
407/844-5100, FAX: 407/848-0627
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