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2
Abstract: slide # 3
Dramatis Personae: slide # 4
Introduction: slides # 5 9
Methods: slide # 10
Result & Data: slides # 11 17
Discussion: n.a.
References: slide 18
Comments and translation of key-sentences from
the „Historical Excursion“: slides # 19 - 22
Historical Excursion: interviews along the „micro bubble controversy“,
excerpts from „UWF“, the D-A-CH magazine for underwater video- &
photography. Copies of 03/1991 & 01/1992 on the:
pages 23 28
3
Abstract:
Here in Part III, we take a look back and follow the development of a couple
of european air diving tables for recreational diving. This historical path
is mirrored in the development of the first european diver-carried computers.
We give samples of these tables along our ubiquitous test profile:
42 m, 25 min on air. We close the presentation with a historical excursion
from the very depth of our archives, describing the controversy during the
‘90s around „micro bubbles“.
The rest of the story could be found in „Digging up the past“, Part I & II,
pls. cf. Refs. [1] & [2].
4
Dramatis Personae:
AAB: Albert Alois Bühlmann, born 16.05., one-hundred years
ago in Berlin, working in Zürich, Switzerland in the Cardio-Pulmonary Lab,
more details there:
https://www.divetable.info/BS_ZH/Medical_Research_ZH.pdf
JH: Jürgen Hermann, founder of Divetronic AG, Liechtenstein; they produced
a diver carried dive-computer (DC), called the „Hans Hass Deco-Brain“.
More details concerning the Deco-Brain‘s and a manual there:
https://www.divetable.info/kap2_e.htm
and there in photos: https://www.divetable.info/skripte/Deco-Brain.pdf
MH: Dr. Max Hahn, physicist, diving instructor CMAS ***, the DECO 2000
air decompression tables being his last work, died in 2000 during a CCR dive
due to hypercapnia/hypoxia.
And, finally: our boss, head-of-lab, ALBI.
He knows all of the above persons from various meetings, especially
MH, which whom he shared a deep interest in the matters, the same
professional approach and a couple of beers on various VDTL medicine
seminars in the ‘80s …
5
Introduction (1):
The Zürich air diving tables, called ZH-x with the ISO
abbreviation „ZH“ for Zürich (Zuerich, a town in Switzerland (CH)),
the place where AAB worked and build the „DKL-USZ“, the
Druckkammerlabor-Universitätsspital Zürich (Hyperbaric Chamber Laboratory
University Hospital Zuerich). The “-x” is for the year the tables were being
published in print (pls. cf. the “Synopsis” on slide # 11)
The ZH-83 and then the ZH-86 became the “gold standard”–tables for air
diving in the recreational domain, especially through the tables for altitude
diving. As the perfusion algorithms with the 16 theoretical compartments for
each inertgas in the breathing mixture were described in-depth in AABs
epic series of books (pls. cf. next slide), these algorithms, called “ZH-L 16A, -
B and –C, became as well a gold-standard for software implementations in
diver carried computers (DC) and desktop decompression software.
Liechtenstein, the place where JH lived and the company DIVETRONIC was
situated, is not far away. DIVETRONIC produced the series of “Deco-Brain”
dive computers; these, in turn, became the DC proto-types in the D-A-CH
region. Before Divetronic went bankrupt, ca. 5,000 units have been sold,
according to JH.
7
Introduction (3):
MH worked together with both and was responsible for the
adaption of the a-/b-coefficients, on one part for the air diving tables
(AAB-MH table (1984), pls. cf. slide # 12) and as well for the Deco-Brain II
with the software versions P2-2 and P2-3 (the P2-1 was a table-interpolator),
pls. cf. slide # 15.
The pre-decessor of the ZH-L16x was the ZH-L12, where the sub-script 12
denoted only the number of 12 pairs of coefficients for the 16 compartments.
In the „ZH-L 16x“ nomenclature, the
„ZH“ is for Zürich
„L“ is for linear, since the equation to compute the allowed/tolerated
inertgas overpressure per theoretical compartment is a simple, linear one.
This yields as well for all the predecessor models from Haldane, Workman,
Schreiner and Müller/Ruf!
the x = A,B,C is for A: theoretical considerations
B: the table calculations
C: the DC calculations
8
Introduction (4):
The ZH-L story became so successful that a lot of
script-kiddies put the algorithm into a piece of PC-software.
Thus, in the ‘90s Ed Thalmann (of USN) once said to Karl Huggins
(of ORCA & Edge) during an UHMS workshop:
„Any idiot with a computer can create a set of tables!“.
And, as well the ZH-L became the boilerplate for all following algorithms,
like a ZH-L6 for the MicroBrain series of DCs; the Aladin with ZH-L6, 8, 12 &
16; adaptive versions like a ZH-L8 ADT and the topical versions with the
Gradient Factors (GF) like the ZH-L16C GF, already available in a lot of DCs!
9
Introduction (5):
In the beginning of the ‘90s, the cooperation split up.
One of the reasons was probably the controversy around the „micro bubbles“:
pls. cf. the attachment with the historical excursion. The other was probably in
their personal traits: all of the 3 had the knack of making enemies, easily …
This is as well reflected in the historical excursion …
MH started to create Deco ‘92 air diving tables in the versions 1 & 2, there-
after the Deco 2000 (pls. cf. slide # 14). These became slightly more
conservative than their ZH-predecessors and the altitude went down from
700 (ZH) to 250 m above sea-level (AAB-MH 1984) and then up again to
700 (‘92).
Now, in the after-math it is easy to see that this controversy was completely
counter-productive. The flag-ship DCs of the leading manufacturers / brand-
names like the G2 TEC from Scubapro, and a lot of Shearwater products
have now a ZH-L 16C GF. Even companies which, in the past, boasted of
their „bubble models“, are slowly converging in, like the Genius (Mares)
and the latest Suunto DCs.
10
Methods (1):
Our company standard profile to test algorithms, tables
and DCs is: 42 m bottom depth, 25 min bottom time, either with Air,
EAN/Nitrox, Trimix or Heliox as the gas for breathing.
In the synopsis (pls. cf. next slide) the increasing conservativism, or,
for that matter, the increasing TTS along the time axis (top bottom)
is shown. Or, as one of our colleagues has put it once:
„In the past, divers were divers and men were men: the attitude towards
DCS has changed since“.
11
Synopsis for the 42 m / 25 min dive:
Table Schedule Stop times
[min] @
12 m
Stop times
min] @
9 m
Stop times
[min] @
6 m
Stop times
[min] @
3m Stop times +
ascent time TTS
[min]
DKL 40 / 25‘ - - 3 12 15 + 4 19
DKL 45 / 25‘ - - 5 20 25 + 4.5 30
ZH-83 42 / 25‘
- 3 5 14 22 + 3 25
Deco-
Brain II
with P2-2
42 / 25‘ - 4 5 19 28 + 4.2 33
ZH-86 42 / 27‘ - 4 7 19 30 + 3 33
AAB-
MH 84
42 / 25‘
- 3 4 12 19 + 4.2 23
Deco
2000
42 / 25‘ 1 4 8 16 29 + 4.2
33
ZH-
L16C
GF
42 / 25‘
GF:
0.9 / 0.9
1 4 9 22 36 + 5 41
18
References:
[1] Salm, A. Eisenstein, Y. (2023)
Digging up the past (Part I):
a controlled dry, repetitive dive with seasoned dive computers (2009)
DOI: 10.13140/RG.2.2.19725.72166
[2] Salm, A. Eisenstein, Y. (2023)
Digging up the past (Part II):
a controlled dry, bounce dive on air to 51 m; 10 years later … (2019)
DOI: 10.13140/RG.2.2.30093.51681
19
Comments to the historical excursion (1):
Some comments and key-sentences translated (in the brackets).
In clear & easy hindsight, there were a couple of remarks far out in the left field:
from 03/91, p. 118:
- … die ersten Tauchcomputer 1983 auf den Markt kamen …
(when the first DCs appeared in 1983 on the market)
the DecoBrain was not the first dive computer world-wide, there have
been pre-decessors in Canada and the US around 1979; this even more so
concerning the features of the boxes: the CyberDiver III from CTF
around 1980 had much more to offer for the civilian diver.
The ORCA Edge was also commercially available before the Deco-Brain II
(the Deco-Brain I was only a table-based interpolator, it could not enjoy a full-blown
decompression calculation due to limited CPU- & RAM power).
As well there is a patent from the chief-designer from the USN,
Kirk E. Jennings (US Patent No. 4005282), which described a
helluva features not available in european dive computers until the late 90‘s
from 03/91, p. 118.
- … das System ZH-L16 - eine originäre Schweizer Leistung ...
(the system ZH-L16 - an original swiss achievement ...)
20
Comments to the historical excursion (2):
… no: it was not: the perfusion models, as alread pointed out on
slide # 7, have been around for ca. 80 years, as well the linear equations for the
supersaturations. The utilization of 16 compartments was already done long before
AAB by Schreiner et al. and Müller/Ruf. What is really left is that the AAB
convolute (slide # 6) was one of the first and complete descriptions publicly
available!
from 03/91, p. 119
- Leider wird über das Thema insgesamt allzuoft unqualifiziertes Zeug geredet.
Nehmen Sie z.B. JH ... und MH ... die sich beide in tauchmedizinische Bereiche
einmischen, obwohl sie keine medizinische Promotion haben. Den wirren und sich
meist selbst widersprechenden Aussagen nach zu urteilen ist JH für mich sowieso
ein Psychopath. MH ... hat … nicht die geringste experimentelle Erfahrung.
(Unfortunately, the topic as a whole is all too often unqualified stuff talked.
For example, take JH... and MH... who are both meddling in dive medicine
areas, although they don't have a medical doctorate. Judging by the
confused and mostly self-contradictory statements, JH is a psychopath to
me anyway. MH ... doesn't have the least experimental experience)
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Comments to the historical excursion (3):
AABs verdict, that JH is a weirdo was, unknown to him at that
time, to become bitterly true around 2014, ca. 20 years after AABs death:
after JH sold out the remains of DIVETRONIC to Scubapro/UWATEC, he went
into investment banking. But his epic commercial failure he did not assign to his
incompetence in these matters: instead, JH filed a 200-million-€ case against the
state of Liechtenstein, killed his private banker and committed suicide afterwards.
from 01/92, p.12 & 14
a comment from H.W. Keller, then the boss of KELLER AG,
who owned that time ca. 50 % of the DIVETRONIC shares,
on the history of DIVETRONIC and the cooperation between
AAB, MH & JH, how it started and how it broke up.
from 01/92, p. 14
feedback from SCUBAPRO on the Aladin-Pro, NC11 & DC11
computers. In the divers magazines in these times, the new Scubapro
computers have been ridiculed as a "shower computer“ due to the
relatively short NDL, the no-decompression limits.
feedback from MH about the algorithms to calculate micro bubbles
22
Comments to the historical excursion (4):
All these information would have been very difficult to collect for
an average competent writer for a diving magazine: the internet,
as we we know & use it today (2023) was in its infancy:
the browsers not graphically, but command-line oriented,
the response-times of search-machines (called gophers & web-crawlers,
that times …) not in seconds but hours & days …
