Emulation of the USN NEDU experimental dive profile A1 with a decompression shareware

Abstract

In a trailblazing study from the Navy Experimental Diving Unit traditional shallow and deep stops schedules have been analyzed. As the shallow schedule did reveal significant less DCS cases in comparison to the deep stop schedule, we set about to emulate the shallow schedule with a decompression shareware using a standard perfusion model with 16 parallel compartments and gradient factors. The USN air table and the experimental shallow schedule could be emulated easily with pairs of GFs so that the prognosed time-to-surface matched. For the original USN table we used 0.90 / 0.90 and for the experimental shallow schedule (A1) 0.345 / 1.236.

Full text

1
Emulation of the USN NEDU
experimental dive profile A1
with
a decompression shareware
Miri Rosenblat, TAU
Nurit Vered, Technion Haifa
Albi Salm, SubMarineConsulting
(16.11.2023)
@ TEC 4.0: update! Eilat / IL
DOI:

2
Emulation of the USN NEDU
experimental dive profile A1
with
a decompression shareware
Contents:
Abstract: chart # 3
Introduction: chart # 4
Methods: charts # 5  7
Results: charts # 8 10
Data: charts # 11  17
Discussion & Conclusion: n.a.
References: charts # 18 & 19

3
Emulation of the USN NEDU
experimental dive profile A1
with
a decompression shareware
Abstract:
In a trailblazing study from the Navy Experimental Diving Unit
traditional shallow and deep stops schedules have been analyzed.
As the shallow schedule did reveal significant less DCS cases in comparison
to the deep stop schedule, we set about to emulate the shallow schedule with
a decompression shareware using a standard perfusion model with 16
parallel compartments and gradient factors.
The USN air table and the experimental shallow schedule could be emulated
easily with pairs of GFs so that the prognosed time-to-surface matched.
For the original USN table we used 0.90 / 0.90 and for the
experimental shallow schedule (A1) 0.345 / 1.236.

4
Introduction:
In a trailblazing study from the Navy Experimental Diving Unit (NEDU) [1]
traditional shallow (A1) and deep stops (A2) air-diving schedules have been
analyzed.
As the shallow A1 schedule did reveal significant less DCS cases in
comparison to the A2 deep stop schedule, we set about to emulate the A1
schedule with a decompression shareware using a standard perfusion model
with 16 parallel compartments (ZH-L 16C) and two gradient factors (GF),
the GF High and the GF Low, [2] and all the references therein.
These new pairs of GF could then be used to modify already published
schedules and check, if unrealistic decompression prognoses would surface
[3].

5
Methods (1):
First we compared the seasoned air-diving tables USN [5],
DCIEM and ZH-86 and tried to emulated then the most
conservative schedule with the ZH-L16 C and the two GFs.
The conservative-candidate was the USN 2018 table (pls. cf. the RESULTS
section: row A in Table I) with the TTS of 101 min. DCIEM & ZH-86 prognosed
more liberal schedules (row C & D in Table I).
We used a variational parameter search for the two GF, a GF High and GF
Low. As a constraint we used a matching time-to-surface (TTS) resp. the sum
of all stop times (TST, total stop time) within an error margin of +/- 2.5 min.
For the USN tabled schedule we found a
GF Hi = GF Lo: 0.90 / 0.90 (Row B in Table I)
For the experimental shallow schedule A1 we found:
GF Hi = 0.345 and GF Lo = 1.236 (Row B in Table II).
In Table II, Row C, the deep schedule A2 is for comparison only as it
matches the TST.

6
Methods (2):
The basic parameters like water density, water temperature,
ascent rates and respiratory coefficients have to be adapted,
since they differ in the various frameworks; pls. cf. as well DATA sections:
 Geometric diving depth: 53.2 m
 Albert Alois Bühlmann safety factor  depth * 1.03 + 1.0 [m]
 Respiratory coefficient Rq = 0.9
 Water density per USN Manual, Table 2-10: 64 lbs/ft3
 fsw to m (also from table 2-10): 0.312616 @ 15° C
 Ascent rate = 30 fsw / min = ca. 9.4 m / min
 USN table schedule: 30 fpm = ca. 9.144 m / min
The DATA sections 3 & 4 show the used parameters via on-line screen shots
from the DIVE 3 framework [2] during emulation of the A2 schedule.
The delta-times from TST (total stop times) to TTS (time-to-surface) are
negligible here due to statistical variations for depth, time and temperature
measurements during real-world diving.
With the sets of GFs we checked as well our ubiquitous test-profile of 42 m,
25 min, air to see if any unrealistic stop times would surface, pls.cf.
RESULTS, Table III.

7
Methods (3):
Additional resources used:
 One possible mapping of the original USN VVAL algorithm for the 2018
air tables [5] to a modified 16-compartment perfusion model has been
positively checked by us in 2022 [4].
Another possible mapping of the DCIEM framework for repetitive air- &
heliox dives to a modified 16-compartment perfusion model with GF has
been positively checked by us as well in 2022, [6] & [7] and all the
references therein.
The most topical DIVE Version 3 software is always on the english
version of the BETA TEST site:
https://www.divetable.info/beta/index_e.htm
(The released candidate, along with the handbook is there:
https://www.divetable.info/DIVE_V3/V3e/index.htm)

8
Results (1): Table I, 170 fsw, 30 min
USN, DCIEM & ZH-86:

depth /
time stops:
[feet]
[ min]
TTS /
TST
[min]
method
↓ 70 60 50 40 30 20 10
A)
USN Air Table 5 7 7 77 TTS =
101
B)
ZH-L16C GF:
0.90 / 0.90
2 4 7 12 23 47 TTS =
100
C)
DCIEM Air Table 6 5 7 11 48 TST =
77
D)
ZH-86
calculated
(for adapted
parameters cf.
METHODS (2)
1 3 7 10 20 39 TTS =
85

9
Results (2): Table II
A1 & A2 schedules from USN NEDU TR 11-06 July 2011;
170 fsw, 30 min:

depth /
time stops:
[feet]
[ min]
TTS /
TST
[min]
method
↓ 70 60 50 40 30 20 10
A)
shallow (A1) 9 20 52 93 TST =
174
B)
ZH-L16C GF:
0.345 / 1.236
1 7 15 38 108 TTS =
174
C)
deep (A2) 12 17 15 18 23 17 72 TST =
174

10
Results (3): Table III
Test-Profile 42 m, 25 min, air:

depth /
time stops:
[m]
[ min]
TTS
[min]
method
↓ 12 9 6 3
A)
ZH-86
calculated
- 3 6 17 29
B)
ZH-L 16 C GF:
0.90 / 0.90
1 4 8 20 36
C)
ZH-L 16 C GF:
0.345 /1.236
(A2 parameters)
- - 4 33 40

11
Data (1):
170 fsw, 30 min:
Comparison with USN Air Table (2018) 9-9, p. 507 :
and DCIEM Air diving table (1983), p. 69:

12
Data (2):
Comparison with ZH-86 air table from Albert Alois Bühlmann:
as the pressure of 170 fsw is neither equivalent to the geometrical depth
of 51 m (167,4 feet) nor 54 m (177,2 feet), we looked up both entries:
both are more liberal than their USN or DCIEM counterparts. As the 54 m-
table ends at 27 min, our calculation reveals for 30 min bottom time @ 54
m (ZH-86 system in fresh water @ 20 ° C) a TTS of ca. 78 min.

13
Data (3): screen shot of on-line parameters from DIVE;
1st. step of the box profile:

14
Data (4): screen shot of on-line parameters from DIVE

15
Data (5): screen shot of on-line parameters from DIVE
Undisturbed
ZH-L 16 C
 in Table I
Row B, with GF
0.90 / 0.90

16
Data (6): screen shot of on-line parameters from DIVE
Undisturbed
ZH-L 16 C
in Table II, Row B, with
GF High = 0.345
GF Low = 1.236
TTS: 174 min
Row A shallow A1 TST: 174 min


17
Data (7): screen shot of on-line parameters from DIVE
Test-profile 42 m, 25 min, air:
Undisturbed
ZH-L 16 C, Row A
GF 0.90 / 0.90
Row B
Undisturbed
ZH-L 16 C, Row A
GF 0.345 / 1.236
Row C
Entries in Results (3), Table III:
Rows A,B,C

18
References (1):
[1] David J Doolette, Wayne A Gerth, Keith A Gault
(22-07-2011) Redistribution of decompression stop time from shallow to
deep stops increases incidence of decompression sickness in air
decompression dives; TA 04-12 NEDU TR 11-06 July 2011
[2] Salm, Albi. (2021). Synopsis & Fact Sheet: PoC for DIVE (Proof of
Concept for a free-/shareware decompression suite).
[3] Rosenblat, Miri & Vered, Nurit & Salm, Albi. (2023). On the reliability of
dive computer generated run-times (01.01.2023) Part X: a conciliatory
proposal of a benchmark.
https://dx.doi.org/10.13140/RG.2.2.18609.66406
[4] Salm, Albi & Rosenblat, Miri & Eisenstein, Yael & Vered, Nurit. (2022).
Recovery of selected U.S.N. Rev. 7 air-diving schedules via a
decompression shareware. 10.13140/RG.2.2.31593.36961.
[5] U.S. Navy Diving Manual Revision 7 Change A 30 April 2018
SS521-AG-PRO 010 0910-LP-115-1921

19
References (2):
[6] Salm, Albi & Eisenstein, Yael & Vered, Nurit & Rosenblat, Miri. (2022).
The mapping of the DCIEM Air-diving table to a standard Haldane-
/Workman-/Schreiner-algorithm. 10.13140/RG.2.2.27420.36480.
[7] Salm, Albi & Rosenblat, Miri & Vered, Nurit & Eisenstein, Yael. (2022).
Recovery of selected DCIEM air-diving schedules via a decompression
shareware. 10.13140/RG.2.2.15208.55046.