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Tom,
You misunderstood me. I am NOT telling people to mix for an END of 120
and try to 'break the record'. While some would say I'd merely be
chlorinating the gene pool, I'm not an instructor, and I'm not going to run
around and tell others how to dive.
What I did was to point out that Bennet showed using narcotic mixes is
not necessary.
And if the briefness of my previous post confused anyone, I'll state:
Yes, rate of compression, and overall depth, seems to be the single most
determining factor, along with individual susceptibility.
Now that I have the disclaimers out of the way -
>>> Some degree of buffering does take place with nitrogen but it does not
> eliminate the need for slower descents<<
We're either talking scuba, and therefore fast descents, or 'supported
diving', in which we can choose our descent rate. Although this is
techdiver, I think we all agree that trying to do a quick bounce to 1000 fsw
with scuba gear, to get your name in Guinness, is a little irresponsible. So
we're talking supported, bell or habitat diving.
I have to tell you, Bennet contradicts what you say then, about 'not
eliminating the need for slower descents', quite clearly.
>>comex and other deep experiential dives as well as other diving reflects
> that divers doing 1000 feet always experience HPNS even with slowed
> descents. <<
Be careful, Tom. In medicine and physiology, there ain't no such animal
as "always". As a matter of fact - Bennet's book is replete with examples of
dives to 1000 ft showing NO signs of HPNS.
Rich L
----- Original Message -----
From: Tom Mount <TOM.MOUNT@wo*.at*.ne*>
To: Rich Lesperance <richl@uf*.ed*>; <kirvine@sa*.ne*>
Cc: <techdiver@aquanaut.com>
Sent: Friday, October 08, 1999 8:42 AM
Subject: Re: INTD "normoxic" and other trimixes
> Rich
>
> al of those who have read the technical diver encyclopedia or the trimix
> student workbook will tell you that rate of descent is the main
controlling
> factor in HPNS. There is a good chapter on HPNS by John Zumrick which
> highly references Bennet and Elliot plus work at EDU and other papers.
There
> is also an excellent chapter on Narcosis by David Dolette Ph.D
>
> Some degree of buffering does take place with nitrogen but it does not
> eliminate the need for slower descents. One of the problems with ultra
deep
> helium based dives is the need that on OC divers must drop fast due to gas
> supply needs.
>
> Rapid descents are the largest contributor to HPNS which is a hydrostatic
> pressure effect as well as other contributors,
>
> comex and other deep experiential dives as well as other diving reflects
> that divers doing 1000 feet always experience HPNS even with slowed
> descents. these same divers also tend to get DCS hits during ascent, but
in
> a bell they are easily managed whereas in OC they would be quite hard to
> manage in OW.
>
> Thus OC ultra deep helium based diving is comparable in risk to ultra deep
> air diving. Interesting experiments done on narcosis equivalents of 500
> feet have shown that the diver goes to sleep in less than one minute. If
you
> have read the accounts of the few who have ventured near these depths you
> see this as a occurrence. When Dan Manion did his 500+ air dive he wrote
of
> seeing the depth gauge read 400 + then again reading 400+ and then he
looked
> at the max depth and discovered he had broken the record at over 500 feet
> but survived due to dropping a drop weight and floated back up to a depth
> that he woke up again. Recently a person in the UK described a deep dive
and
> part of his description was losing vision then remembering at the max
depth
> being shaken by safety diver. Sure sounds like if the safety diver had
not
> woke him up he would not be here today
>
> Point is even with adding nitrogen you cannot prevent HPNS especially on
> rapid descents. Rapid descents are the major contributor. So your
> suggestion of 120 END to drop to 1000 feet would not work just as a deeper
> or shallower END would not work as long as rapid descents are employed
>
> When you read about dives below 850 feet on helium by OC divers you always
> read about tremors and about DCS problems at some point during the dive.
One
> of the contributors to this is the fact that gas supplies to do these
depths
> are limited by the ability to carry them and thus rapid descents (which
> produce HPNS) are required.
>
> IANTD teaches HPNS theory in its trimix course so people do understand
that
> even in helium based dives there are physiological limits to safety such
as
> HPNS just as narcosis and oxygen toxicity are limits in air diving.
>
>
> Respectfully yours,
> Tom Mount
> CEO IANTD World HQ
> http://www.iantd.com
>
> ----- Original Message -----
> From: Rich Lesperance <richl@uf*.ed*>
> To: <kirvine@sa*.ne*>
> Cc: Tom Mount <TOM.MOUNT@wo*.at*.ne*>; <techdiver@aquanaut.com>
> Sent: Thursday, October 07, 1999 11:27 PM
> Subject: Re: INTD "normoxic" and other trimixes
>
>
> > >>. At
> > > the same time, the "discovery" of HPNS and the antiquated stories
> > > showing use of anesthetics as an offset ( rather than correct decent
> > > rates), is an easy opening for the deep air addicts to get off the
wagon
> > > and get themsleves a nice buzz,<<
> >
> >
> > Regarding HPNS and the need for 'anaesthetic' nitrogen pressures -
> >
> > This will really piss off the Deep Air crowd, but Bennet et al. found
that
> > even with a rapid descent (100 ft / min) down to 1000 fsw (why a scuba
> diver
> > is going that deep is a mystery, but...), the amount of nitrogen needed
to
> > ameliorate HPNS is NOT seriously narcotic. I did the math, once, and it
> > worked out to something like an END of 120 fsw or so.
> >
> > Anyone thinking I'm pulling this out of my a**, check Bennet's book, the
> > chapter on HPNS & Inert Gas narcosis.
> >
> > Rich L
> >
> >
> >
> > ----- Original Message -----
> > From: <kirvine@sa*.ne*>
> > To: Bill Mee <wwm@sa*.ne*>
> > Cc: Tom Mount <TOM.MOUNT@wo*.at*.ne*>; <techdiver@aquanaut.com>
> > Sent: Thursday, October 07, 1999 12:09 PM
> > Subject: Re: INTD "normoxic" and other trimixes
> >
> >
> > > Bill, I was wondering why Tom was mentioning HPNS - I thought maybe he
> > > was teaching welding at 800 feet now.
> > >
> > > The fact is that only the worst moron would try to dive deep enough on
> > > scuba, which includes rebreathers, to be worried about HPNS - the
reason
> > > the have to worry about it on scuba is that they are trying to decend
> > > too fast, given that they have neither enough gas nor enough time to
do
> > > the correct deco for the correct decent rate. Commercial diving with a
> > > push/pull rb from a bell with a ship dives to severe depths and works
> > > for hours with no problem, and no "air", but then they are not trying
to
> > > prove anything, they are doing a job.
> > >
> > > These guys who feel the need to do this need to just get with a good
> > > psychiatrist and talk it out rather than kill themselves trying to
prove
> > > that they do not have a case of pinkydickism, which even saying the
word
> > > HPNS is this context implies in my opinion.
> > >
> > > You can't fix weenie with a trimix course. A weenie is a weenie, and
> > > diving does not cure being a weenie.
> > >
> > > However, as you point out , Bill, some of these third world
desperadoes
> > > have little to live for , and nothing to lose, and nobody who cares.
At
> > > the same time, the "discovery" of HPNS and the antiquated stories
> > > showing use of anesthetics as an offset ( rather than correct decent
> > > rates), is an easy opening for the deep air addicts to get off the
wagon
> > > and get themsleves a nice buzz, what they are so hungry for but lack
the
> > > balls to go do correctly on land.
> > >
> > > Diving is in a pathetic state, in my opinion, and we do not have to
look
> > > very far to see the continuously approaching Burnham Woods of shielded
> > > stupidity and whence it originates.
> > >
> > > Bill Mee wrote:
> > > >
> > > >
> > > > Tell me, why on earth is the subject of HPNS even brought up in the
> > course.
> > > > HPNS is irrelevant to anything in meaningful, routine technical
> diving.
> > > > Where HPNS is even a consideration, the depths and rigors of the
dives
> > fall
> > > > into the category of commercial saturation diving, which is
conducted
> by
> > a
> > > > far more repsonsible and rational set of rules. I can only guess
that
> > the
> > > > allure of "deep" and the assoication of "deep" with HPNS is the
reason
> > for
> > > > injecting this subject matter into a course where the focus should
be
> on
> > far
> > > > more mundane issues. This is equivalent to filling a course in
> freshmen
> > > > chemistry with topics from quantum electrodynamics. The implication
> is
> > that
> > > > students need to be concerned with diving at depths of 400 to 500
ft,
> > which
> > > > while romantic, is simply absurd.
> > > >
> > > > You need to seriously reconsider revisit these policies before
> somebody
> > else
> > > > does so for you.
> > > >
> > > > Best regards,
> > > >
> > > > Bill
> > > > -----Original Message-----
> > > > From: Tom Mount <TOM.MOUNT@wo*.at*.ne*>
> > > > To: kirvine@sa*.ne* <kirvine@sa*.ne*>
> > > > Cc: a n <techdiver@aquanaut.com>
> > > > Date: Wednesday, October 06, 1999 11:20 AM
> > > > Subject: Re: INTD "normoxic" and other trimixes
> > > >
> > > > >George
> > > > >the text includes the Technical Encyclopedia, the technical student
> > > > workbook
> > > > >a complete set of slides it is extremely well supported and in is
our
> > > > >preferred dive program for people getting into deeper diving. The
> > majority
> > > > >of instructors are able to get students who originally wanted to do
> > > > >technical diver to take this course as instead.
> > > > >
> > > > >I have no doubt that some people state they are comfortable on air
> toi
> > > > >greater depths however even if the technical diver program is taugh
t
> > they
> > > > >are forbidden to dive deeper than 170 feet. The technical diver
> course
> > does
> > > > >require two dives deeper than 130 and no dives below 170.
> > > > >
> > > > >The Normoxic course is basically the same course except it does
dives
> > on
> > > > >trimix instead of air. The student is NOTALLOWED to dive air deeper
> > than
> > > > 130
> > > > >in this program. As has been stated several times on this list over
> the
> > > > past
> > > > >three years. The student does not have any requirement to have
dived
> > air
> > > > >deeper than 130 prior to getting into the course in fact they do
not
> > even
> > > > >have to have been to 130 just deeper than 90 feet prior to the
> course.
> > The
> > > > >Normoxic trimix is a heavy deep diving theory course it does not
get
> > into
> > > > >HPNS and some other factors as these things are not of a concern to
> > > > Normoxic
> > > > >trimix. It is intense on skills and procedures. the course requires
3
> > dives
> > > > >deeper than 130 and a max depth not to exceed 200. Depths are
worked
> up
> > to
> > > > >in increments no greater than 30 feet from one dive to the next.
> > > > >
> > > > >
> > > > >The HPNS and other issues are addressed in depth in the trimix
course
> > where
> > > > >dives may evolve into dives that that knowledge is mandated. The
full
> > > > trimix
> > > > >course has six dives also 2 of which can be on air or mix as they
are
> > just
> > > > >skill dives and need not be deep. Four dives are on mix and must be
> > deeper
> > > > >than 160 and no deeper than 260
> > > > >
> > > > >Again if people wish details go to the web page and read through
the
> > > > >standards
> > > > >
> > > > >Respectfully yours,
> > > > >Tom Mount
> > > > >CEO IANTD World HQ
> > > > >http://www.iantd.com
> > > > >
> > > > >----- Original Message -----
> > > > >From: <kirvine@sa*.ne*>
> > > > >To: Tom Mount <TOM.MOUNT@wo*.at*.ne*>
> > > > >Cc: a n <techdiver@aquanaut.com>
> > > > >Sent: Wednesday, October 06, 1999 8:45 AM
> > > > >Subject: Re: INTD "normoxic" and other trimixes
> > > > >
> > > > >
> > > > >> T, that is not the question - the question is what materials are
> > > > >> available for these courses. I personally have zero interest in
> this,
> > > > >> but had it mentioned to me by an IANTD instructor on a dive boat
> the
> > > > >> other day, the implications being that these courses are an
> > accomodation
> > > > >> to outside pressure and are neither well supported by IANTD, nor
> > really
> > > > >> intended to replace "deep air". I of course found this hard to
> > believe
> > > > >> so sent you that question to see if it were really possible.
> > > > >>
> > > > >> Tom, there are people out there, believe it or not, who are so
> stupid
> > as
> > > > >> to think ther is such a thing as an "ability" to dive deep on
air,
> > and
> > > > >> there are intstructors out there who are so stupid, and so
> > irresponsible
> > > > >> that they say things like, "my personal comfort level on air is
200
> > > > >> feet" in front of students, who then take this to mean that
unless
> > they
> > > > >> "can" be "comfortable" on air at "200 feet", they must not be
> cutting
> > > > >> the mustard.
> > > > >>
> > > > >> I know this is unbelievable to a pro like yourself, but I have
> heard
> > > > >> this direcdtly from the flapping lips of various instructors,
> > > > >> affilliation unknown.
> > > > >>
> > > > >> Anything that pays lip service only to the importance of proper
gas
> > > > >> choices and true technical diving (which menas doing the dives
> > proeprly
> > > > >> and optimally), is a disservice to all of us, and in my opinion
> would
> > > > >> require the attention of a dive training "leader" such as
yourself
> > for
> > > > >> clarification.
> > > > >>
> > > > >>
> > > > >> Tom Mount wrote:
> > > > >> >
> > > > >> > Anyone interested should go to the web pages and check the
> > standards
> > > > for
> > > > >the
> > > > >> > texts and also the skills. that should answer anyone's
questions
> > > > >> >
> > > > >> > Respectfully yours,
> > > > >> > Tom Mount
> > > > >> > CEO IANTD World HQ
> > > > >> > http://www.iantd.com
> > > > >> >
> > > > >> > ----- Original Message -----
> > > > >> > From: <kirvine@sa*.ne*>
> > > > >> > To: <TOM.MOUNT@wo*.at*.ne*>
> > > > >> > Cc: <techdiver@aquanaut.com>
> > > > >> > Sent: Tuesday, October 05, 1999 3:45 PM
> > > > >> > Subject: INTD "normoxic" and other trimixes
> > > > >> >
> > > > >> > > Tom, I hear that there are little or no materials for your
> > > > "normoxic",
> > > > >> > > "intermendiate" or whatever "trimix" course. This would
appear
> to
> > > > make
> > > > >> > > this course a case of "lip service" to those of us who have
> long
> > been
> > > > >> > > critics of your "deep air" courses and policy.
> > > > >> > >
> > > > >> > > While I like the fact that you to at least appear to comply
> > with
> > > > >> > > intelligent thinking, I find it appalling that the reality is
> you
> > > > >still
> > > > >> > > may not.
> > > > >> > >
> > > > >> > > Is this true?
> > > > >> > >
> > > > >> > >
> > > > >> > >
> > > > >>
> > > > >>
> > > > >>
> > > > >
> > > > >
> > > > >
> > >
> > >
> > > --
> > > Send mail for the `techdiver' mailing list to
`techdiver@aquanaut.com'.
> > > Send subscribe/unsubscribe requests to
`techdiver-request@aquanaut.com'.
> >
>
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