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>Myth 8: DIR and its proponents have saved many student divers from
>certain danger and possible death, as taught by all other training
>agencies. Reality: No agency is trying to kill you. The agencies
>that have been in the business longest have enviable safety records,
>a testimonial to their quality of instruction, given the inherent
>dangers involved in scuba.
Enviable safety records?! Mike, I don't know what the source of your
statistics is, but I think you might want to independently verify them. If you
look at diving accidents as attributed to training agency, it paints a much
different picture than your above paragraph. Regardless, it is obvious that no
agency is purposefully attempting to kill students. Compare the student
standards between the agencies (available on the web) to determine which one
has the highest standards.
>To review (in reverse order):
>
>Myth 7: DIR is a system for everybody. Reality: Personal preference
>is the system for everybody. You have the right to choose DIR or the
>right to choose another system, or to incorporate useful parts of any
>system that suits your needs. No single system will ever be the panacea
>for everybody.
Nobody is denying you your right to choose, Mike. The DIR system will never be
appropriate for everybody, because it is a systemic approach to diving based on
logical reasoning with safety as the most important consideration. Not
everyone places safety as the first priority, nor do they all have the ability
to comprehend the reasons behind every decision in DIR as it relates to
equipment selection, configuration, profile and gas planning, teamwork or
emergency procedures. Regrettable, but then DIR has never been about hitting
everyone over the head with a 2x4, to coin an expression. It's about doing
stuff that makes sense for those who want to learn to dive as safely as
possible.
>Myth 6: DIR is a system based on experience and proven facts.
>Reality: Although many DIR divers have experience in technical diving,
>there are many among them who extrapolate facts to the point of
>distortion, confusion, and lack of truth. The message soon becomes
>lost in all the noise.
I disagree with this assertion. I think that the internet personalities of the
most vocal DIR proponents tend to generate a lot of superfluous discussion,
with the net result that the actual issues are deemphasized. It is easy to get
caught up in the "noise" you refer to - just look at our discussion now. Most
of the DIR proponents on the internet forums would easily be dissuaded from
addressing the issues on their own merits, due to the fact that individuals
like yourself appear at first impression to lack the basic ability to
comprehend the technical issues at hand when discussed rationally. I can
understand their frustration, but agree that contributing to such noise is
nothing but counterproductive.
>Myth 5: DIR is a new movement in scuba that will grow and someday
>surpass other systems. Reality: Tech diving will continue to grow,
>but the training agencies that will attract the most students are the
>ones with time-honored teaching skills, including respect, patience,
>and avoidance of name-calling such as DIR's infamous "stroke."
Again, back to the noise issue. DIR diving is growing, due in large part to
GUE. The training agencies that attract the "most" students have always, and
will always be those agencies which offer the easiest and cheapest courses.
Global Underwater Explorers (the definitive DIR training agency) has a
different objective - that being not to produce the "most" divers, but rather
the "best" divers ("best" in this case referring to the ability to conduct a
dive safely and not become a statistic in the future).
>Myth 4: DIR is practised by the BEST divers in the world. Reality:
>The BEST divers in the world are too busy diving and conducting
>research to be sitting around posting to techdiver, rec.scuba, the
>GUE list, Rodale's, or any other newsgroup in cyberspace. The BEST
>divers in the world, with few exceptions, are conspicuously absent
>from these lists.
This depends entirely on what your definition of "best" is. If I want
information from the groups which perform the world's most difficult cave
exploration dives, consistently produce the best cave and wreck diving video,
search and rescue/recovery groups that operate under the most difficult
conditions while simultaneously having the highest success rates, the groups
which are on the cutting edge of decompression and dive physiology research,
the groups who are actually consulted by the US military, the groups who work
with the researchers that actually develop the decompression models, and the
groups that consistently conduct deep wreck dives all over the world without
incident, I will look to DIR.
>Myth 3: DIR uses safe procedures, both in and out of the water.
>Reality: DIR uses procedures that do not comply with guidelines
>established by NOAA and the U.S. Navy, including flying only three
>hours after a deep deco dive, in-water recompression for decompression
>accidents, diving well beyond recreational limits and simultaneously
>striving to shorten decompression times, exercising shortly after
>diving, plus others which are hardly safe.
What do the NOAA and the US Navy have to do with anything, Mike? Both of these
groups are government agencies, and neither group performs recreational mixed
gas dives on open-circuit SCUBA. US Navy special warfare has actually
consulted with the WKPP on decompression techniques, as everyone but the NEDU
(and DCIEM in Canada) is constrained by existing standards and regulations, and
even NEDU is incapable of producing the amount of real-world data that
originates with groups such as WKPP. Flying only three hours after a deep deco
dive - as a physician with an interest in diving physiology, Mike, it surprises
me that you are not familiar with the work of Drs. Chimiak and Johannsen -
particularly with respect to post dive bubble doppler studies. Evidence
(empirical, repeatable, real-world evidence) has demonstrated that with a
strict fitness regime, the absence of preconditions such as PFO, and the proper
application of decompression gases and profiles, the traditional bubble
distribution over time can be shifted to peak and decay much closer to the
actual surfacing time than was previously believed. The time-to-fly guidelines
you are familiar with are long-standing (overly conservative) recommendations
based empirically on an average sample base which obviously does not imply the
same preparation. As for in-water recompression, it's funny that I didn't see
you at the last UHMS symposium on the topic, but then I guess when you know
everything you have no reason to benefit from personal discussion with the
leading researchers in these fields. Funny that your name was never mentioned,
but since you seem to be so knowledgeable in the field, I assume that you have
at least read the transcripts, in which case I ask you why you feel that in-
water recompression is such a poor idea, when conditions warrant? Diving well
beyond recreational limits - well Mike, not having any technical diving
experience yourself to speak of, I suppose I can let this (seemingly
ridiculous) point slide, but I emplore you to take half a second to notice what
forum it is you are posting this stuff to. Striving to shorten decompression
times - what is wrong with this? Shorter decompressions mean less time in the
water, where conditions are unpredictable, less opportunity for hypothermia,
easier gas planning, and less physiological damage since the decompression
effectiveness is increased. For the commercial and military guys (who use this
info, remember?) it means less money spent. Everybody wins. What's the
problem here? Exercising shortly after diving - does this point refer to a
particular post? Vigorous exercise immediately following a dive is not a
recommended practice, since it causes bubbling, but I suspect this discussion
may have had something to do the with the post-dive doppler studies addressed
above. Intuitively, when the peak occurs earlier, you can see that it is
possible to begin exercise earlier without causing a problem. As for the other
practices that are "hardly safe", would you care to list these? You're
batting .000 so far, and maybe you can redeem yourself. At the very least, we
can discuss the specific issues, and not revert to superfluous noise again.
>Myth 2: DIR is useful for cave diving, but can be applied to ALL forms
>of diving. Reality: Very few people use DIR outside of cave diving,
>because the system is inflexible and impractical. In fact DIR teaches
>using NO COMPUTER, only a bottom timer, hardly a practical
>recommendation nowadays.
Oh good - an actual issue. I hope you can forgive me for not being original in
this post, Mike, but as I have explained this one a few times, I am just going
to paste the text from previous discussions on the topic. I hope it is of
value:
>
Planning the dive and sticking to the plan is the best idea, but when you don't
have a specific objective in mind or the site is new, it is a simple matter to
estimate an appropriate profile on the fly. The first step is learning what the
actual shape of the decompression profile looks like. Desktop decompression
software is useful in this regard, but even without that, you can graph off of
tables to get a feel for this. If you run several depths and times, including
multilevel dives if you choose, you will begin to see patterns emerge with
respect to how the shape of the curve is affected by extending the bottom time,
changing the depth, or changing the gas you are breathing. By understanding the
process, you can easily determine an appropriate decompression profile for most
dives. For recreational diving it's even easier, as all you need to do in that
case is stay within your NDLs. Multilevels are accomodated by simply using a
weighted average depth.
Keep in mind that any computer algorithm does not accurately reflect what is
occurring in the human body - the idea of having to follow a computer profile
to within seconds is humourous in that respect. By ditching the computer and
actually learning how to do this, you place yourself in a position of being
able to deal with device failure, or an unforseen profile change which would
cause a computer to lock up or otherwise excessively penalize you. Not using
computers also means that you and your dive buddy always are following the same
plan, and if your device craps out, guess what - your buddy has one that will
be displaying exactly the same information. The profile to be followed is
communicated prior to the ascent, and everyone is on the same page.
Most of the diving I do incorporates planned decompression, but to illustrate
an example, I might cut a series of tables using a deco software program or any
standard algorithm - I learn the table based on breathing 32% (or whatever gas
you use most often). By "learn the table" I do not mean memorizing every depth
and time number specifically to the foot or minute, but rather, to learn the
pattern. Decompression is an exponential relationship, as with any other in
nature (with the caveat that this is modified with deep stops and the like).
Breathing higher PO2 increases your NDL, take the average bottom depth to
figure your multilevel dives in terms of a square profile, etc. If I were to
switch to deco gases, I cut the time accordingly - going on 50% at 70 fsw, I
cut every stop above that in half. If I add oxygen at 20fsw, I cut the 20 and
10 foot stops in half again - Instant emergency bailout procedure, since the
table I know is the one that applies to the scenario where I have lost all of
my deco gas.
I carry tables in my pocket for more extreme dives or profiles which I am not
familiar with, but only as a reference should I require it. Dive computers,
IMO, only allow you to become complacent since you are relying on your computer
to calculate profiles rather than spending a bit of effort to learn what is
going on. The computer also allows you to do stuff like sawtooth profiles and
so forth with a false sense of security. You can see from this thread that
typically people are having to use more than one of these, due either to their
unreliability, or to the variance in the factory algorithms (which,
incidentally, are commonly overconservative for liability reasons, and also
which commonly use poor algorithms, such as unmodified Bulhman ZHL16s). IMO, a
poor solution to a self imposed problem.
For what it's worth.
<
>Myth 1: DIR has had no fatalities or accidents. Reality: Bobby
>McGuirre, a WKPP/DIR diver, died while diving DIR in a cave, and
>represents at least one accident DIR cannot deny.
I should appropriately defer this one to someone closer to the issue for
comment, but it is my understanding that Bobby switched to a mix that was too
high in oxygen for his depth, succumbed to oxygen toxicity and died. The DIR
standards for correct bottle marking, identification and employment are
designed to eliminate the possibility of this sort of incident occuring, and in
fact, if those standards are employed correctly, it is impossible to do so.
>MJB :-)))
-Sean
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