PresentationPDF Available

On the theoretical evaluation of one yo-yo diving profile on air for fish-farming

  • SubMarineConsulting


On the theoretical evaluation of one yo-yo diving profile on air for fish-farming Abstract: A yo-yo diving profile is one with very rapid and repeated depth changes. Due to the speed of depth changes in excess of 20 m/min and the quickly repeated ascents and descents within 1 to 5 min, a standard decompression model based on perfusion or a dive computer or a logging device can no longer track the changes in the inertgasload in the diver’s body properly. One form of ubiquitious yo-yo diving is done in fish-farming, clearly needed to change air-tanks, tools, debris and locations within a multiple array of the fish-nets. The already available historic sources ([1], [2], [4], [5] & [6]) address this topic clearly and the connected risks but without hints of complete mitigation. We propose simple & straightforward modifications of an existing perfusion model [12] to mitigate the risk of decompression sickness and/or arterial/ cerebral air embolism.
On the theoretical evaluation of
one yo-yo diving profile on air
for fish-farming
DOI: 10.13140/RG.2.2.: t.b.d.!
A yo-yo diving profile is one with very rapid and repeated depth changes.
Due to the speed of depth changes in excess of 20 m/min and the quickly
repeated ascents and descents within 1 to 5 min, a standard
decompression model based on perfusion or a dive computer or a logging
device can no longer track the changes in the inertgasload in the diver’s
body properly.
One form of ubiquitious yo-yo diving is done in fish-farming, clearly needed
to change air-tanks, tools, debris and locations within a multiple array of the
The already available historic sources ([1], [2], [4], [5] & [6]) address this
topic clearly and the connected risks but without hints of complete
We propose simple & straightforward modifications of an existing perfusion
model [12] to mitigate the risk of decompression sickness and/or arterial/
cerebral air embolism.
Methods (1):
The yo-yo profile in question is the one from: [5], p. 24:
Methods (2):
A quick check with available desktop deco software programs (pls. cf. the
„Bonus Material“ at the end of this presentation and [3]) confirmed
the findings from [1], [4], [5] & [6];
the calculated
inertgas loads
do not suggest
any decompression
or safety stop:
(the used color
scheme for the
heat maps was
proposed by DAN
within the
DSL framework)
Methods (3):
To keep track on the inertgas loads in the various theoretical tissue-
compartments during the rapid pressure changes due to fast ascents and
descents, compartments with very small half-times (HT), i.e.
high perfusion rates, have to be introduced.
Since 6 halftimes are needed to saturate (or desaturate) these theoretical
compartments, haltimes in the minute resp. sub-5-minute ranges are clearly
required, so one compartment with a halftime of ca. 70 secs and a 2 min
compartment are added on the fast side of the halftime-spectrum from [12];
and one intermediate compartment with a HT of ca. 9 min is added as well
These new fast compartments are pretty well in-line with the data,
extracted from Paulev [9], [10] & [11] resp. [8] on p.19.
Methods (4):
With [7], p. 6 and the aid of [12], p. 129:
where, in the a-coefficient, the 3rd. root of the half-time τ is, according to
Buehlmann, an indicator to the excess volume of inertgas and thus could
be mapped onto the simulated bubble volumes of [7].
Methods (5):
Source: [7], p. 5:
[7], p. 6:
Methods (6):
The new compartments were tailored to the a-/b coefficient scheme of the
ZH-L 16 framework [12] with a clear stress to fast compartments to keep
track of the expedited change in inertgas loads. The yellow display are the
new and overpressure-
sensitive fast compartments.
Compartment #2 with
2 min halftime (TAU) is
calculated according to the
rule from [12], p. 129, but was
never used by Buehlmann.
The rest of the compartments
are original Buehlmann,
the gradient factors High &
Low equal to 1.0, i.e.: 100 %.
Methods (7):
Since Haldane [13], p. 346 the abundance of inertgas (micro-)bubbles is
associated with delayed de-saturation, i.e. prolonged half-times. This is as
well addressed, for example, in the EL-algorithm used for the new USN air
diving tables ([14]).
Here, we use a compartment matrix with increased halftimes of 50 % in the
first 8 compartments only for
the 5 ascents of this
yo-yo profile:
Results (1):
By using these modified ZH-L coefficients matrices
(pls. cf. slide #8 for descent, slide #9 for ascent) already during the first
ascent a decompression / safety stop of ca. 1 min is suggested:
This even more so after the
consecutive 4 descents/ascents:
Results (2):
During the consecutive ascents the ceiling / safe ascent depth
increases from ca. 2.35 m to 2.45 and the stop times accumulate from
1 min to ca. 4 min: after the complete series of 5 bottom times and 5 ascent
spikes, our modified model suggests a
decompression stop > 4 min at a stop depth of ca. 4 +/-2 m.
an even higher benefit
in terms of reduced
inertgas load could be
achieved by changing
the breathed gas to
100 % oxygen at
approx. 6 m
during the last,
the 5th. ascent
and a final stop:
The extreme form of repetitive diving like the yo-yo profiles
used for professional fish-farming can not be adequately
adressed neither by standard perfusion models like the ZH-L16 or a Workman
algorithm ([2], [5], [6]) nor by standard diffusion models ([1], [4]) since the used
compartment half-times resp. diffusion coefficients are not fitting to the fast
inertgas absorption / release processes during the spikes of the yo-yo profile.
Instead, fast compartments with half-times in the sub-minute region should be
We extracted fast-compartment data [8] with a half-time of ca. 70 sec
from [9] [11] which are in-line with a recently developped new model [7].
Thus the tested profile required short and shallow decompression resp.
safety stops already for the first spike of the yo-yo series. After the complete
series of spikes, our model suggest a stop > 4 min @ 4 m +/- 2 m.
Sources / References (1):
[1] Smart DR, Van den Broek C, Nishi R, Cooper PD, Eastman D.
Field validation of Tasmania’s aquaculture industry bounce-diving
schedules using Doppler analysis of decompression stress. Diving and
Hyperbaric Medicine. 2014 September:44(3):124-136
[2] Bühlmann, A.A. (1987) Decompression after repeated dives, Undersea
Biomed Res. Vol. 14, #1, p. 59 - 67 (3810993)
[3] the SubMarineConsulting Group(1991) DIVE: a decompression suite;
pls. cf. slide #16
[4] Diving methods and decompression sickness incidence of Miskito Indian
underwater harvesters RG DUNFORD, EB MEJIA, GW SALBADOR, WA
GERTH, NB HAMPSON, UHM 2002, Vol. 29, #2, p. 75 -85
Sources / References (2):
[5] Hahn, Max. H. (1995) Workman-Bühlmann Algorithm for Dive
Computers: a critical analysis; in: Hamilton, R.W. (ed.) The effectiveness of
dive computers in repetitive diving; p. 19 25
[6] Hahn, M.H. (1992) Dive Computers Today and Tomorrow; in: Wendling
/Schmutz (eds.) Safety Limits of Dive Computers, Dive Computer
Workshop, p. 30 35
[7] SaulGoldman,J.M.Solano-Altamirano (2015) Decompressionsickness in
breathholddiving and its probable connection to the growth and dissolution
of small arterial gasemboli, Mathematical Biosciences262(2015)19;
[8] Salm, Albrecht (2018) Essay on fast and super-fast compartments;
DOI: 10.13140/RG.2.2.30451.35366
Or there: Tech Diving Mag, Issue 30 / 2018:
On Fast- and Super-fast Compartments, p. 10 -20
Sources / References (3):
[9] PAULEV, P. Decompression sickness following repeated breathhold dives.
J. Appl. Physiol. 20(5) : 1028-1031. 1965
[10] PAULEV, POUL-ERIK, AND NOE NAERAA. Hypoxia and carbon dioxide
retention following breath-hold diving. J. Appl. Physiol. 22(3) : 436-440. 1967.
[11] PAULEV, POUL-ERIK. Nitrogen tissue tensions following repeated
breath-hold dives. J. Appl. Physiol. 22(4): 714-718. 1967
[12] Bühlmann, Albert A., Völlm, Ernst B. (Mitarbeiter), Nussberger, P. (2002):
Tauchmedizin, 5. Auflage, Springer, ISBN: 3-540-42979-4
[13] Haldane, J S. Respiration, Yale University Press,
1922, 1927
[14] Thalmann ED, Parker EC, Survanshi SS, Weathersby PK. Improved
probabilistic decompression model risk predictions using linear-exponential
kinetics. Undersea Hyper. Med. 1997; 24(4): 255 274
Bonus Material (1):
Source for
DIVE Version 3_09
Download free of charge:
DIVE V 3_09
and the german manual
The release train for
the english version (V3_04) is somewhat slower
DIVE V 3_09 is not compatible with all older versions!
Bonus Material (2):
3 ASCII (text) files with the data,
for easy reference & download
The nitrogen coeffcients matrix für saturation
(descents & bottom time), slide #8:
The nitrogen coeffcients matrix für de-saturation
(ascents & decompression / safety stops), slide #9:
The calculated inertgas pressures in the 16 compartments,
after the 5th. spike, that is: the completed yo-yo profile,
prior to ascent, i.e. run-time 46.5 min):
Bonus Material (3):
the heat-map, prior to the last stop, run-time 48 min
The paradigm dive from above via these commands,
the input of commands and parameters are in the quotes: „ “
d“ (simulation of one spike of the yo-yo box profile with these
15.“ (bottom depth)
8.“ (bottom time)
a“ (ascent)
the manipulation of the coefficients matrices is done via:
nc“ (nitrogen coefficients):
with the option 3 the matrices from
slides #8 & 9 could be loaded
into the service engine of the
DIVE software.
The heat maps are generated via:
Handling of DIVE:
Fine tuning could be done via the commands:
ascent rate („AR“)
ambient atmospheric pressure at start („L“)
the respiratory coefficient („R“)
the ambient (water)-temperature („te“)
the water density („di“)
Buehlmann Safety Factor („B“)
last stop depth („LS“)
And with: „awe recieve the complete decompression prognosis;
i.e.: the stop times in min per stage, modulo 3 m
and the responsible leading compartment & the rounded up TTS in
min. The latest DIVE Version for beta testing is always staged there:
along with information on production date, size in bytes, new features and
the checksums for verifying the download.
Fine tuning of DIVE:
Full-text available
Synopsis & fact sheet for the Desktop Decompression Suite DIVE, Version 3_11; new features being the K-Index for CNS- & P-OT, as well the DCIEM deco stress index "I".
Full-text available
Synopsis & Fact Sheet: an update per 07/2021 wit new materials / publications for a Proof of Concept (PoC) for DIVE Version 3_10; including links to: --> Collateral Aspects of DCS --> an agile implementation of the K-value, a severity index for CNS-OT & P-OT (oxygen toxicity for the CNS and the pulmonary system)
Conference Paper
Full-text available
If there is more than one inertgas in the breathing mixture, the calculation of the decompression-time td has to be done numerically. We analyzed 480 square / box dive-profiles in the TEC/REC range with one freeware, two commercially available software-packages and via numerical methods (depth range: 30 - 80 m, bottom times: 20 - 60 min, helium percentage: 5 - 80 %, only normoxic mixes i.e.: no travel- or enriched deco gases, only ZH-L model, no adaptions with gradient factors). There are significant differences in the calculation of the decompression-times td with trimix gases, obviously dependent on the helium percentage. In the present analysis, these differences do not come from variations in the decompression algorithms.
Full-text available
Synopsis: some collateral aspects of DCS A collection of papers / essays / presentations and their URLs at, related to DCS (decompression sickness), PBPK (physiologically based pharmaco-kinetic models), diving and their somewhat remote, unusal or at least, unorthodox aspects.
Full-text available
PoC: proof of concept DIVE: a decompression suite as a free-/shareware for: dive / decompression planning with open system / SCUBA bounce/jump/sprint dives in the TEC & recreational domain saturation diving custom models for: diving at reduced ambient pressure, low water temperature diving with high workload / oxygen consumption C&R diving, Caisson- & tunnel work
Full-text available
Essay on Fast and Superfast Compartments
Full-text available
We solved the Laplace equation for the radius of an arterial gas embolism (AGE), during and after breath-hold diving. We used a simple three-region diffusion model for the AGE, and applied our results to two types of breath-hold dives: single, very deep competitive-level dives and repetitive shallower breath-hold dives similar to those carried out by indigenous commercial pearl divers in the South Pacific. Because of the effect of surface tension, AGEs tend to dissolve in arterial blood when in arteries remote from supersaturated tissue. However if, before fully dissolving, they reach the capillary beds that perfuse the brain and the inner ear, they may become inflated with inert gas that is transferred into them from these contiguous temporarily supersaturated tissues. By using simple kinetic models of cerebral and inner ear tissue, the Nitrogen tissue partial pressures during and after the dive(s) were determined. These were used to theoretically calculate AGE growth and dissolution curves for AGEs lodged in capillaries of the brain and inner ear. From these curves it was found that both Cerebral and Inner Ear Decompression Sickness are expected to occur occasionally in single competitive-level dives. It was also determined from these curves that for the commercial repetitive dives considered, the duration of the surface interval (the time interval separating individual repetitive dives from one another) was a key determinant, as to whether Inner Ear and/or Cerebral decompression sickness arose. Our predictions both for single competitive-level and repetitive commercial breath-hold diving were consistent with what is known about the incidence Cerebral and Inner Ear Decompression Sickness in these forms of diving. Copyright © 2015 Elsevier Inc. All rights reserved.
Introduction: Tasmania's aquaculture industry produces over 40,000 tonnes of fish annually, valued at over AUD500M. Aquaculture divers perform repetitive, short-duration bounce dives in fish pens to depths up to 21 metres' sea water (msw). Past high levels of decompression illness (DCI) may have resulted from these 'yo-yo' dives. This study aimed to assess working divers, using Doppler ultrasonic bubble detection, to determine if yo-yo diving was a risk factor for DCI, determine dive profiles with acceptable risk and investigate productivity improvement. Methods: Field data were collected from working divers during bounce diving at marine farms near Hobart, Australia. Ascent rates were less than 18 m·min⁻¹, with routine safety stops (3 min at 3 msw) during the final ascent. The Kisman-Masurel method was used to grade bubbling post dive as a means of assessing decompression stress. In accordance with Defence Research and Development Canada Toronto practice, dives were rejected as excessive risk if more than 50% of scores were over Grade 2. Results: From 2002 to 2008, Doppler data were collected from 150 bounce-dive series (55 divers, 1,110 bounces). Three series of bounce profiles, characterized by in-water times, were validated: 13-15 msw, 10 bounces inside 75 min; 16-18 msw, six bounces inside 50 min; and 19-21 msw, four bounces inside 35 min. All had median bubble grades of 0. Further evaluation validated two successive series of bounces. Bubble grades were consistent with low-stress dive profiles. Bubble grades did not correlate with the number of bounces, but did correlate with ascent rate and in-water time. Conclusions: These data suggest bounce diving was not a major factor causing DCI in Tasmanian aquaculture divers. Analysis of field data has improved industry productivity by increasing the permissible number of bounces, compared to earlier empirically-derived tables, without compromising safety. The recommended Tasmanian Bounce Diving Tables provide guidance for bounce diving to a depth of 21 msw, and two successive bounce dive series in a day's diving.
Seventy-six men and 7 women performed a 2nd dive in a pressure chamber under dry conditions after intervals at the surface of 10, 30, 90, or 120 min. Of these, 35 persons performed a 3rd dive after an interval of 20 or 90 min (118 repeated dives). Air was the breathing gas during all phases of the tests. During exposure to overpressure the divers exercised on a bicycle-ergometer. The decompressions for dives 2 and 3 were the same as for the first dive. After the 2nd or 3rd dive, certain symptoms of decompression sickness of the skin occurred in 5 of the 118 exposures, and 1 diver complained of muscular aches. These results suggest that no general sensitization occurred after the 1st dive. We concluded that a slightly more conservative decompression with regard to ascent velocity and profile is feasible for repeated dives.
A report is given of a case of apparent decompression sickness after repetitive breath-hold dives to depths of 50–66 ft (15–20 m). Three similar cases in Norwegian Navy escape-training-tank instructors are also discussed. A parallel is drawn between the Scandinavian cases and the“pearl diver disease”(taravana), found in the Tuamotu Archipelago in the South Pacific. Symptoms and signs in these conditions are consistent with the diagnosis of decompression sickness. It is emphasized that in such cases immediate recompression is the treatment of choice. Consideration of various depths and patterns of breath-hold diving in terms of nitrogen uptake and elimination permits the relative risk of decompression sickness to be predicted with the help of decompression tables. skin diving; recompression; repetitive diving; nitrogen uptake; taravana; nitrogen elimination Submitted on September 25, 1964
Using a data base of 2,383 air and nitrogen-oxygen dives resulting in 131 cases of decompression sickness (DCS), risk functions were developed for a set of probabilistic decompression models according to survival analysis techniques. Parameters were optimized using the method of maximum likelihood Gas kinetics were either traditional exponential uptake and elimination, or an exponential uptake followed by linear elimination (LE kinetics) when calculated supersaturation was excessive. Risk functions either used the calculated relative gas supersaturation directly, or a delayed risk using a time integral of prior supersaturation. The most successful model (considering both incidence and time of onset of DCS) used supersaturation risk, and LE kinetics (in only 1 of 3 parallel compartments). Several methods of explicitly incorporating metabolic gases in physiologically plausible functions were usually found in lumped threshold terms and did not explicitly affect the overall data fit. The role of physiologic fidelity vs. empirical data fitting ability in accounting for model success is discussed.
Diving conditions, dive profiles, and symptoms of decompression sickness (DCS) in a group of Miskito Indian underwater seafood harvesters are described. Dive profiles for 5 divers were recorded with dive computers, and DCS symptoms were assessed by neurological examination and interview. Divers averaged 10 dives a day over a 7-day period with a mean depth of 67 +/- 7 FSW (306 +/- 123 kPa) and average in-water time of 20.6 +/- 6.3 minutes. Limb pain was reported on 10 occasions during 35 man-days of diving. Symptoms were typically managed with analgesic medication rather than recompression. Indices of the decompression stress were estimated from the recorded profiles using a probabilistic model. We conclude that the dives were outside the limits of standard air decompression tables and that DCS symptoms were common. The high frequency of limb pain suggests the potential for dysbaric bone necrosis for these divers.
DIVE: a decompression suite
the SubMarineConsulting Group(1991) DIVE: a decompression suite;