Decompression Expert OR Internet Spin Doctor
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:email@example.com]
And pushing the envelope a bit too hard. You need back
off for awhile here.
Special Note: Bruce Wienke's reference to "Fluid
Shifts" is more totally irrelevant rubbish! For
more irrelevant ramblings, read any of his books!
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.
This article will be updated soon with more outrageous quotes from the "experts"
You will particularly like the ones where Bruce Wienke boasts of designing my 313metre dive profile, even supplying a copy of the dive plan used. Predictably the VPM experts also went on scubabored a mille second later, implying that my dive plan was clearly a bubble model and a mirror of VPM. I have never published my dive plan and it certainly does not look like an RGBM or VPM plan despite what the internet marketeers state.
Unfortunately it seems that Bubble model internet marketing strategies are believed by some. Even more sadly they were actually followed by two European divers to 316m and 320m in 2004, both divers were predictably horrendously injured.
The words and reputations of "experts" can indeed inflict terrible injuries.
Dive Safe, Dive Educated
copyright Mark Ellyatt