dive computers vs dive tables vs WKPP practices

[100days-a-year]

Scuba ,I recently did some web research on a website that Delta_P reccomended PubMed and found research done from a variety of international sources.Simply due to the amount of resources in the US/UK and EU it seems likely they will be heavily represented.I found quite a bit of studies from Russiaand a few from other more eastern countries.

 

[Dr Deco]

Dear SCUBA SOURCE Readers:

This is an interesting question. Much scientific material is published in some scientific journals and this is independent of the country of origin. Russian scientists have been able to publish for the past ten years but there is not a great deal of output. This is probably a reflection of the economy that is still recovering from the management of the Soviets.

Commercial methods might never be published since they are proprietary. I am not aware of any proprietary Russian research in diving.

Much material is disseminated at scientific meetings, and eastern scientists can attend these if they choose. Very often, smaller studies are presented in papers that are read at the meetings. Simply put, most material is from the US and the Europe since these regions are financially the strongest and able to put much money into the game. They also have many trained scientists. This does not mean, however, that there are not some very clever people in other places. There certainly are. Many times these people will have one good idea, and one such idea is worth twenty trivial ones.

Dr Deco :doctor:

 

[Kendall Raine]

The WKPP website indicates a 7 hour dive in Wakulla, average depth 285 ffw, requires 8 hours and 5 minutes of deco. I understand this is basically a sat exposure so not BT dependent beyond here. This schedule is found at the Maximum Decompression Procedures section under Decompression at www.wkpp.org.

Do you know how WKPP developed this schedule which, as you point out, is so much shorter than RGBM? Dr. Powell once expressed the thought such curves were self-selected inasmuch as those who could not handle the deco stress self-selected out of the program leaving only those individuals who could tolerate the load. Is there a varient of RGBM which proscribes a curve similar to this or is WKPP just "off the scale?"

BRW once bubbled...
DennyB is right on about WKPP. A standard WKPP
dive to 300 fsw for 5 hrs requires 20 hrs of Haldane
deco. RGBM requires 12 hrs. And WKPP does the dive
with 12 hrs deco. Irvine, Jablonski, and Mees have clocked
and recorded it. My hat goes off to them for their
exploits. Plus the balls to experimentally arrive at such
profiles by systematic application of deep stops and
shallow deco time shaving WELL before RGBGM came online
in the tec arena. Their website (search GUE) contains a
wealth of info and history -- do check it out.

 

[Dr Deco]

Dear SCUBA SOURCE Readers:

Many divers who, to my knowledge, are just “regular Joes” perform the WKPP dives. By “selection,” I was referring to the commercial divers such as would be found in the Torres Straight or the black coral divers of Hawaii. There are numerous stories of individuals who are paralyzed in these geographical locals because they could not “keep up” with the decompression schedules of the more DCS resistant divers. They were "selected out."

Paralyzed divers are not in the WKPP region and these schedules are true decompression advances. I still would like to see a test as to whether much of the effect is not the result of the loss of nuclei and the failure to regenerate them because of the “adynamia” (= suspended in the water and lack of musculoskeletal stress).

Dr Deco :doctor:

 

[BRW]

Readers,

George's switch schedule on the WKPP site is NOT the
one I reference in my posts (12 hrs RGBM deco = actual WKPP
deco) and in my books (TDID, RGBM In Depth, Basic Deco
And Apps). This one is nominal with a switch to EAN50 at 70 fsw.

See TDID, RGBM in Depth, Basic Deco And Apps for details

WKPP, C & C (us) and others have used many switch
schemes off basic trimixes. Most of us now ride He as far
as logistics allow to the surface before switching to pure O2.
Deep switches to nitrox DO not occur. And switch dynamics
look like an RB with constant (as small as possible) N2 levels.
N2 is the devil's gas and we avoid it like the plague.

Back to George's WKPP schedule on the site. We have
generated it with RGBM by:

1) -- increasing the amount of separated phase tolerated
(larger than the usual amount fixed by maximum likelihood
in RGBM parameter space)

2) -- decreasing the number of bubble seeds excited off the
micronuclei distribution (again, away from maximum
likelihood fits to the nominal RGBM).

So, as Dr D hints, if we could correlate data underscoring
reduction in micronuclei under rather static deco, we could
then fold that into RGBM. I have no doubt this mechanism
plays into deco diving thru tribonucleation. I just need
data to pinpoint the cross correlation. Getting that data is
tough in real divers.

George has the RGBM calc that corresponds to the schedule
on the WKPP site. And I "published" some time ago to
the deco and techdiver lists (sent it as a mass emailing).

Great questions, and this is really getting at the core
of where modern deco modeling stands, and is able to
reflect real dynamics (not just curve fitting).

Bueno, and cheers,

Bruce Wienke
Program Manager Computational Physics
C & C Dive Team Ldr

 

[Kendall Raine]

My understanding is not all WKPP dives involve the types of exposures encountered by the deep gas guys-depicted under max deco. The max decos are where the acceleration is most pronounced. There are lots of set-up dives (to stage bottles and scooters) involving more modest exposures, though imperative of using the right curve is throughout. Also, some support divers may limit their exposures to shallow portion of deco. So, while fitness requirements are strict, potential deco stresses vary widely depending on role. Also, most, if not all, cave penetration and deep set-ups are scooter dives with sufficient redundant scooters to almost assure one doesn't need to swim out.

I suspect "average joe" might qualify for WKPP if we're talking "average" by NASA standards. I'd be surprised if average joe would qualify by general dive population standards.

I was not suggesting WKPP regularly generates a sub set of bent and discarded divers, though hits have occured amongst support divers. Please accept my apology if I misconstrued your self-selecting remarks. Whether in Wakulla or the Torres Straight, however, it seems intuitive that some will better stand the stress than others regardless of deco regime.

 

[BRW]

Readers,

Regarding my earlier post, also note that Wakulla dives to
300 fsw/300 min are vastly different than the 3 - 4 deco repets
of Torres Straits Pearl divers to successively shallower depths
after a 300 fsw dive for 10 - 15 minutes.

Gas loadings vary, and gas diffusion into and out of seeds
varies mucho.

WKPP uses mixed gases. The Torres Straits folks used
air (yeh, oh my God).

The dynamics of micronuclei excitation, suppression, and
control differ also. Wakulla divers make long horizontal
penetrations and remain fairly static on their deco glide path.
And they are are saavy tech group. Pearl divers did it
for a living, and were hardly static above or below the
waterline. And were not a saavy group.

Bruce Wienke
Program Manager Computational Physics
C & C Dive Team Ldr


WKPP, C & C Switches

George's switch schedule on the WKPP site is NOT the
one I reference in my posts (12 hrs RGBM deco = actual WKPP
deco) and in my books (TDID, RGBM In Depth, Basic Deco
And Apps). This one is nominal with a switch to EAN50 at 70 fsw.

See TDID, RGBM in Depth, Basic Deco And Apps for details

WKPP, C & C (us) and others have used many switch
schemes off basic trimixes. Most of us now ride He as far
as logistics allow to the surface before switching to pure O2.
Deep switches to nitrox DO not occur. And switch dynamics
look like an RB with constant (as small as possible) N2 levels.
N2 is the devil's gas and we avoid it like the plague.

Back to George's WKPP schedule on the site. We have
generated it with RGBM by:

1) -- increasing the amount of separated phase tolerated
(larger than the usual amount fixed by maximum likelihood
in RGBM parameter space)

2) -- decreasing the number of bubble seeds excited off the
micronuclei distribution (again, away from maximum
likelihood fits to the nominal RGBM).

So, as Dr D hints, if we could correlate data underscoring
reduction in micronuclei under rather static deco, we could
then fold that into RGBM. I have no doubt this mechanism
plays into deco diving thru tribonucleation. I just need
data to pinpoint the cross correlation. Getting that data is
tough in real divers.

George has the RGBM calc that corresponds to the schedule
on the WKPP site. And I "published" some time ago to
the deco and techdiver lists (sent it as a mass emailing).

Great questions, and this is really getting at the core
of where modern deco modeling stands, and is able to
reflect real dynamics (not just curve fitting).Readers

 

[Kendall Raine]

BRW;

Thank you for the explanation. Sorry if you've explained the evolution elsewhere (if it's at the deco ftp site please feel free to just send me there and I'll find it).

I'm curious as to how adjustments 1 and 2 from maximum likelihood were derived. Was this theoretical or iterative, or both? That is, did consideration of fitness, scootering and switching protocols (to name a few factors) drive the modifications from nominal, or did WKPP divers simply shorten deco from nominal RGBM and come back with empirical results (Doppler, VC and other post dive data) before adjusting factors?

Either way, how "specific" to WKPP (divers, conditions, protocols) are adjustments like this and can we expect evolution of RGBM based upon this in versions released to others?

Many thanks,

Kendall

 

[BRW]

Kendall,

Good questions -- far beyond normal RGBM queries.

RGBM (full up) is rolled over data (RGBM Data Bank) in
maximum likelihood for certain model parameters. We extract
them from profile data. Data is tec, deco, extreme, mixed gas
etc diving. Not recreational diving, which, in all due respect,
tells us virtually NOTHING in model correlations. The rec DCS
incidence rate is in the noise -- like 1/100,000, which is really
statistically insignificant. (we thus wonder about rec DAN
PDE, and their focus on rec computer downloads for their data.
The new generation of RGBM rec computers with deep stops, will
be useful now to them, we believe. WKPP, C & C (us), NAUI Tec
are real weight calibration points over tec diving).

Back to your question.

The RGBM params coming out of ML are essentially hardwired
into all RGBM software accessible to users (GAP, ABYSS,
Hydrospace simulator), in all Tables (NAUI, RGBMdiving.com),
and all computers (Suunto, Dacor, Mares, Plexus, Hydrospace,
Zeagle, Steam Machines, etc). Some three params related
to material strength of surfactants (beebees to soap bubbles),
diffusion lengths for inert gas transfer across bubble interfaces,
and Boyle material response are allowed to vary (within limits)
for users, yielding aggressive to conservative staging against
the folding over the DB. See RGBM In Depth for details

What I did in fitting George's profile was outside all of the
nominal hardwiring, instead, using the most aggressive
parameter space available at limits.

Such capability requires greater sophistication, and will not
be made available to RGBM users for awhile yet.

Regards,

Bruce Wienke
Program Manager Computational Physics
C & C Dive Team Ldr

 

[cdennyb]

Now that it seems everyone who's contributing to this thread has entered their two cents worth (and much of it was worth far more than that in my opinion!) I have one last question on the subject:

We all seem to agree, to one degree or another, that the NAVY tables are wrong. The PADI Tables are pretty wrong, and that would go for most every deco plastic card table out their in someones dive box printed before say, oh 1990 or thereabouts.
What would it take to get the industry in general to re-write the dive cards and 'wheels' to reflect the deco profiles that are produced with say...V-Planner or GAP software, etc.?

Take any PADI or other deco card and run a software program like those discussed in this thread and you'll see the complete difference in the profiles. Since most divers entering into the sport are interested in obtaining the latest regulator, the fastest scooter, the best tank, the cutiest mask, etc. it would also seem to me they'd want to be taught with the latest technologically advanced deco profiles, Hummmm?

Any comments from our illustrious leaders in the area of physics and decompression science about how we can demand the instructors and oganizations step up and adopt the latest and most accurate for our up and coming new divers?

thanks in advance...
db