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The truth is out there, but its often impossibly difficult
to find. A couple of years back I completed a 260metre dive that resulted in
terrible decompression injuries. The program that generated the plan was Abyss,
the Algorithm RGBM. The bends I received were treated and I contacted
Abyss and Bruce Wienke (developer of RGBM) to advise the outcome. Bruce's
replies were not as expected and are detailed below. I had used the RGBM
algorithm many times before, both shallow (60-90m) and deep (120m-260m),
contrary to Bruce Wienke's website I received DCS every time using the RGBM
algorithm. Satisfactory results were obtained only after manually adding
significant extra shallow decompression stops, usually in the order of hours of
extra time. I have used the VPM a/b algorithms since they became available, also
with similar results, only the version using VPMbE (2005) with maximum
conservatism provides acceptable decompression times.
I will get to the point now because thousands of divers
who still use Abyss and RGBM are continuing to put their health in grave danger.
Abyss users should not use the
RGBM algorithm option.
Divers should not use the RGBM algorithm within
Abyss as it has been programmed badly according to Dr Bruce Wienke.
Interestingly, the RGBM algorithm was launched within Abyss Dive Software and
according to Bruce Wienke's own website was developed by him, although in the
face of a recent law suit, he denies having much involvement in Abyss/RGBM
implementation. Bruce Wienke is fully aware of the dangers inherent in Abyss
software, yet he has decided not to inform the Abyss user base, instead he
harvests bends data from users (similar to VPM) in an attempt to make the
algorithm less full of holes.
Decompression software's typical users are internet
enabled technical divers who sometimes, and through no fault of their own get decompression
sickness after following the decompression schedule properly. All manner of
things are usually blamed for getting DCS, but things may not be what they seem.
Below is a fairly damning email from Bruce Wienke to
Mark Ellyatt. It points out problems with Abyss staff and their lack of
understanding about decompression. Ironically it also states one Abyss staff
member was expelled from NAUI for training violations. Bruce Wienke is
responsible for some gross ETHICS and SAFETY violations also, yet I have not
read of his NAUI membership being revoked. At the top of the email it is clear
to see the email is copied to senior management at the NAUI technical division,
who also decided that safety comes second.
The following email text is dated July 2003...one of a
series of exchanges taking place after
the problematic 260m dive of Feb 2003.
Abyss software went bankrupt to avoid further
litigation from numerous sources soon afterwards. The software has still not
been withdrawn or any advisory notes issued
From: Bruce Wienke [mailto:brwtech@earthlink.net]
Sent: 09 July 2003 05:15
To: Mark Ellyatt
Cc: Nauitec@aol.com; EANx@aol.com
Subject: RE: Ellyat On GAP/ABYSS RGBM
Hi Mark,
Glad you are back
Damn, I thought your earlier email was about 500 ft dives and vestibular probs.
We haven't
seen vestibular probs above 500 - 400 ft on tmix, heliox, etc, with isobaric
nitrox switches
in the shallow zone, so please fill me in with your problematic 1000+ ft dives.
You definitely
are one or two data points, blazing some frontiers.
And pushing the envelope a bit too hard. You need back
off for awhile here.
I am quite worried about you on 1000+ ft dives -- using any algorithm, OC, or RB.
Judas, you are likely up against fluid shifts in the inner ear. Having done some
3D hydrodynamic flow calcs in 3D, fluid flows/shifts appear to worsen for
isobaric switches. I am trying to get a better handle on all variables. Fast
compartments at 34+ atm do have enough "driving power" to push things around, no
matter what mix. Please send me you profiles/ switches/mixes/etc. when you can.
They are important research points. And a favor -- blow off those 1000 ft dives
for the time being. For your questions, please see comments between ************
in your email text below.
Read on, in addition to the above.
BW
----- Original Message -----
From: Mark Ellyatt
To: brwtech@earthlink.net
Sent: 7/8/2003 7:25:27 AM
Subject: GAP/ABYSS RGBM
Hi Bruce,
I have been corresponding with Kees Hofwegen from GAP software who has
recently incorporated RGBM in his deco software.
Kees has advised me that the software has an effective depth limit of
600' (180m) and that this depth limit was imposed by you, something to
do with diffusion codes etc.
**********************************************************
Yes, data only goes down to 500 ft or so. Code operates for any depth.
And works on bubbles -- not fluid shifts. BW
******************************************************
Do you know how Abyss software gets around this problem, as the version
that I have quite happily produces RGBM profiles down to 305m.
*******************************************************
Same comment as above. ABYSS doesn't stay in close touch with me,
has had probs with implementation (mentioned to me by Chris), and
I am not sure if they have fully implemented the same code as GAP.
ABYSS, of course, receives all the same info as GAP, Hydrospace,
Plexus, Mares, Suunto, etc. But be careful with ABYSS, and I say that
in the most respectful way. ABYSS Users often complain to me,
but I try to stay out of personal ranglings. Plus Joel Silverstein at
ABYSS is a difficult person, does not understand RGBM nor deco theory,
and is super pissed off at me as one of 9 NAUI BOD members
who suspended him for ethics and training violations, and then
revoked his NAUI membership. So, deal with Chris on ABYSS/RGBM
matters when you need do so, not Joel. BW
**********************************************************
Does Abyss have a different version of your algorithm than GAP? As you
may remember, I completed a 260m+ dive quite recently and came off
worst! (over burdened inner ear compartment further over loaded with a
counter diffussing gas)
*******************************************************
Don't know (yet) if ABYSS has brought their RGBM up to GAP, as
in the above. Please send me your profiles/mixes/switches on the
1000 ft dives you have done already. Counterdiffusing gas is only
part of prob with fluid shifts. BW
************************************************************
I have plans to go deeper soon, would you say that the Abyss software in
RGBM mode will give acceptable results, If not...why not.
**********************************************************
PLEASE DO NOT GO DEEPER YET -- a few more things need checking.
RGBM will most likely do the best job, but there are some concerns.
BW
*******************************************************
Special Note: Bruce Wienke's reference to "Fluid
Shifts" is more totally irrelevant rubbish! For
more irrelevant ramblings, read any of his books!
I have collected two years of case papers related to a recent lawsuit. I will
put them all on the internet quite soon so divers can learn what the experts are
prepared to do in pursuit of the limelight. What was also interesting was this
case being dismissed on the grounds of a non US citizen bringing a case against
a US company and US individuals, where the alleged accident occurred
outside of the United States. Divers may want to reconsider any purchase of US
products where they will be used outside of the US by non US citizens.
An offer of out of court settlement was rejected as it
likely required non disclosure of all the case related papers!
I wasn't having that!
RGBM as it has never been validated within technical
depths and times. RGBM comes in many flavours, the versions in recreational dive
computers is an overly conservative model developed as a marketing tool to gain
brand recognition for RGBM. The recreational RGBM model offers no benefits over
more traditional algorithms such as DSAT or Buehlmann models (if suitably
applied). RGBM comes in a printed form, again conservative tables used by a
dubious diver training agency. The versions inside software applications aimed
at technical divers are the most dangerous when used aggressively. Even during
minor technical dives, RGBM and its typically inadequate decompression gives
cumulative damage that will present itself over time
Abyss software had/has quite a following. Luckily the
RGBM algorithm was added quite late in its development, and prior to this
technical divers were not attempting particularly aggressive dive profiles.
Below is a text from two other "renowned experts"
explaining just how good Abyss software is! The internet is full of these
dubious endorsements...
A
Hard Look at Decompression Software
By Bill
Hamilton and George Irvine, As printed in DeepTech,
ABYSS, Advanced Dive
Planning Software
Abyss is a
masterpiece. Chris Parrett has really poured his heart and soul into this one.
It is Windows based, and fully incorporates the graphical user interface
inherent in Windows. Abyss provides the user with access to the building blocks
of the decompression algorithm, including such things as factors for each of
thirty-two tissue compartments (32 compartments allow for some fine tuning, but
for practical purposes this is more than is really needed). It offers three
basic variations on the algorithm, using different levels of conservatism
achieved by slowing the outgassing. The latest version now incorporates Dr.
Bruce Wienke's RGBM bubble theory as well. The program allows virtually every
aspect of the dive to be specified with over 800 user modifiable variables
including the user's age, weight, etc. The graphics are fantastic, and the
program is well written and well supported. It comes with an extensive manual as
well as comprehensive on-line help. It also tracks the oxygen limit fraction and
will generate sets of tables entirely or in sections.
Real World Analysis by George Irvine
Most of our
extreme dives are conducted according to commercial tables produced by Hamilton
Research. I checked sample Abyss and DECOM dive plans against dives in my
logbook that produced asymptomatic decompressions which were confirmed by
doppler. Both programs produced tables that matched what I had used, so long as
I injected three or four short deep stops into the plan prior to using the first
stop recommended by each of the programs. Whether or not these deep stops were
necessary is supported only by the fact that I did get mild DCS (Type I) when I
didn't do the deep stops. However, I only allowed this to happen twice in 200
dives, so this is not exactly conclusive. The point is that both Abyss and DECOM
produced tables as good as the custom tables I have used from commercial
sources. I also checked some wreck dive profiles that had worked well in the
field and found the same conformance. These are a very few data points, but they
are better than none.
Dr. R. W. Bill Hamilton is
Founder and President of Hamilton Research. George Irvine is Director of the
Woodville Karst Plain Project and a Stock Broker in Ft. Lauderdale, Florida.
I would imagine the above text disagrees somewhat with
Bruce Wienke's appraisal of Abyss, but who cares? plus its only divers getting
hurt...Heaven forbid the dubious reputations of diving's many religious
leaders are dented.
Hand Bag Fighting of decompression experts is a recent addition to the sport,
coming about at roughly the same time as the re incarnation of bubble models. It
is one that needs stamping out if safety is to be improved. |
