On the reliability of dive computer generated run-times, Part I

Abstract

Abstract:
in Part I we checked a simple run-time for a dive with:
@bottom depth 42 m / bottom time 25 min.
with 2 breathing gases (air & Trimix21/50) with the
Scubapro/UWATEC G2 computer with various firmware releases from
2017 up to now (08 / 2021).

Methods:
pls. cf. slides # 3 to 11, and References [1], [2] & [4], [5]

Results:
there is variation in the TTS from 10 % up to 21 %, depending on
breathing gas and user set conservativism

Discussion / Recommendations: pls. cf. slide #12 & 13

Full text

1
On the reliability of dive
computer generated run-times
26.07.2021, Part I
Miri Rosenblat, TAU
Nurit Vered, Technion Haifa
Albi Salm, SubMarineConsulting
Scubapro / UWATEC
Galileo 2 / G2:
Hardware Version 0.0
Software Version 1.6
per 08/2021

2
On the reliability of dive computer
generated run-times, Part I
Scubapro / UWATEC
Galileo 2 / G2:
Hardware Version 0.0
Software Version 1.6
per 08/2021
Abstract:
in Part I we checked a simple run-time @bottom depth 42 m / bottom time 25
min. with 2 breathing gases (air & Trimix21/50) with the
Scubapro/UWATEC G2 computer with various firmware releases from 2017
up to now (08 / 2021).
Methods:
pls. cf. slides # 3 to 11, and References [1], [2] & [4], [5]
Results:
there is variation in the TTS from 10 % up to 21 %, depending on
breathing gas and user set conservativism
Discussion / Recommendations: pls. cf. slide #12 & 13

3
Scubapro / UWATEC
Galileo 2 / G2:
Firmware versions:
from 1.2 up to 1.6
Scubapro / UWATEC
Galileo 2 / G2:
Hardware Version 0.0
Software Version 1.6
per 08/2021

4
Dive Planner Menu / G2 (11. Tauchgangplaner)
User adjustable conservativism: MB Level L = 0
(Micro Bubble Level = 0, i.e. no gradient factors)
Bottom depth: 42 m; NDL: 8 min
bottom time 25 min @ Air 
Result: TAT / TTS  37 min (V1.6)
Scubapro / UWATEC
Galileo 2 / G2:
Hardware Version 0.0
Software Version 1.6
per 08/2021
(*) TAT = TTS: time-to-surface =
sum of all stop times + ascent time (here ca. 6 min for the G2)

5
Dive Planner Menu / G2: MB Level 0; depth: 42 m;
bottom time 25 min @ Air 
TTS  40 min (V1.2) TTS  47 min (V1.5) TTS  37 min (V1.6)
(*) TAT = TTS: time-to-surface =
sum of all stop times + ascent time (here ca. 6 min for the G2)

6
G2:
MB
Level
G2: V 1.2
TTS [min] G2:V 1.5
TTS [min] G2:V 1.6
TTS [min]
L0 40 47 37
L1 44 52 41
L2 50 58 47
L3 56 65 52
L4 63 73 59
L5 73 84 68
L6 87 100 82
L7 106 120 100
L8 132 146 127
L9 166 180 158

7
Comparison with a standard air
diving table:
 A.A. Bühlmann ZH-86 [3]
and a:
 desktop deco software
pls. cf. Refs [1], [2], [4]

8
Additional Settings required for DIVE V 3_10:
Source: https://www.divetable.info/beta/D3_10.exe
„B“ : Buehlmann Depth Safety Factor
„AR“: ascent rate 7 m / min

9
Comparison with ZH-86 Table:
Source: [65], p. 227; i.e.:
https://www.divetable.info/books/65.pdf
"Tauchmedizin", Albert A. Bühlmann, Ernst B. Völlm (Mitarbeiter),
P. Nussberger; 5. Auflage in 2002, Springer, ISBN 3-540-42979-4

10
Comparison with other
Scubapro/UWATEC Computers
for the dive: 42 m / 25 min bottom time;
each @ Air, @ MB-Level L0
Computertype: TTS Year (ca.)
TEC (1. Generation) 36 2003
TEC 2G 38 2007
Pro Ultra 40 2002
Aladin [2] 40 2014
Matrix 49 2016 (*)
Galileo 2 / G2 40 2017 (*) V 1.2
Galileo 2 / G2 47 2019 V 1.5
Galileo 2 / G2 37 2021 V 1.6
(*) Change from ZH-L 8
to ZH-L 16

TMX 21 / 50 Box Profile @ L0:
42 m / 25 min bottom time
V 1.2: V 1.6:
11

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On the reliability of dive computer
generated run-times, Part I
Scubapro / UWATEC
Galileo 2 / G2:
Hardware Version 0.0
Software Version 1.6
per 08/2021
DOI: t.b.d.
Discussion / Recommendations:
Dive Computer Manufacturers should:
reveal the used set of constants (i.e. used at run-time!)
implement quality assurance procedures
agree on a set of benchmarks, standardized for all players in the market
or a public code-review
For diving activities outside the proven envelope (> 30 m, > 30 min)
therefore the professional use of diving computers , for e.g. for military-,
C&R-, HBOT, public services- & fish farming diving is strongly discouraged.
For reliable, professional use a certain safety-integrity level (SIL, according to
IEC61508) as to be achieved.

13
On the reliability of dive computer
generated run-times, Part I
Scubapro / UWATEC
Galileo 2 / G2:
Hardware Version 0.0
Software Version 1.6
per 08/2021
Discussion / Recommendations:
Since this unreliability is displayed in other scenarios as well, for eg. with
mixed gas run-times, oxygen toxicity calculations, altitude diving adaptions
and the like (pls. cf. refs. [5] & [6], and the SNAFU series @ divetable.info
from 2017 to 2020) we will continue with similar products with Part II.
For civilian use (i.e. TEC / rec divers) outside the proven envelope,
users should not rely on a sole source of information, instead consult :
 accepted dive tables
 verified / open desktop deco software products
 a 2nd./3rd. dive computer.

14
On the reliability of dive computer
generated run-times, Part I
References:
[1] Nurit Vered, Miri Rosenblat; Salm, Albi (2021):
https://www.researchgate.net/publication/349504991_Synopsis_Fact_Sh
eet_PoC_for_DIVE_Proof_of_Concept_for_a_free-
shareware_decompression_suite
[2] Salm, Albi (2020)
https://dx.doi.org/10.13140/RG.2.2.24608.20482/1
[3]  [65] Albert A. Bühlmann, Ernst B. Völlm (Mitarbeiter),
P. Nussberger (5. Auflage in 2002) Tauchmedizin
[4] Nurit Vered, Miri Rosenblat; Salm, Albi (2021):
https://dx.doi.org/10.13140/RG.2.2.28123.69924

15
On the reliability of dive computer
generated run-times, Part I
References:
[5] Salm, Albi (2017) Dive Computer SNAFUs & Crashes
https://www.divetable.info/kap15_e.htm
[6] Salm, Albi (2012) Variation in the TTS: where do they come from?
International Journal of the Society for Underwater Technology, November
2012: SUT, Vol. 31, No. 1, pp. 43 - 47, 2012