dive computers vs dive tables vs WKPP practices

[KLD]

Here are some inputs and ball park stats;

1) -- At DEMA last October, Dick Vann reported and
gave me a diskette with 47 cases of DCS from
some 75,000 profiles at DAN across rec diving,
so rate is approximately 47/75,000;

2) -- rec meter manufacturers reported/estimated
(to us) a DCS hit rate (air/nitrox) of 1/90,000
over the past 10 yrs or so, based on millions
of computer dives;

3) -- records at NAUI Hdqts clocked 50 cases of rec
DCS in 5+ million air/nitrox training dives over
the past 10 yrs or so, so rate is 1/100,000;

4) -- RGBM Data Bank (used to fold RGBM over
diving data) has 16 hits in some 3700 tec,
mixed gas, deco profiles, so rate is 16/3700
in RGBM Data Bank. Some 6 hits were on
deco repets with 2nd dive 50 fsw or more
deeper than first. Others occured with high(er)
ppN2;

5) -- recreational RGBM and classical dissolved gas
algorithms are virtually the same in the no-deco,
single dive arena (but differ on repets, RPs, altitude,
etc), and data there (as seen above) is less
interesting to many folks;

DAN PDE data is mostly rec data, with some tec data based
on Haldane staging (shallow deco stops versus deep stops).
RGBM Data Bank is mainly deep stop staging ala RGBM.
So there are data "differences" (statisticians call these
biases). The USN is now embarking on a very ambitious
program of testing deep stops, and that will certainly
help smooth biases in their early data. All prior USN
data is slanted toward shallow deco stop staging.

Best,

BW

BRW, please help clarify a few points.

Most statistics I've seen show a DCS incidence rate of aproximately 1-5/10,000 for rec. diving. What is the basis for the difference?
I don't recall ever seeing any meaningful statistics for tec diving incidence of DCS. Do you have such data? What is the tec DCS incidence rate?



Seems to me usefull data can be obtained from any dive computer, not just the ones with RGBM algorithm.

Are you, or someone else you're aware of, collecting RGBM and other rec dive data from the general diver population which can be used to statistically compare different algorithms? Tec?

 

[flw]

4) -- RGBM Data Bank (used to fold RGBM over
diving data) has 16 hits in some 3700 tec,
mixed gas, deco profiles, so rate is 16/3700
in RGBM Data Bank. Some 6 hits were on
deco repets with 2nd dive 50 fsw or more
deeper than first. Others occured with high(er)
ppN2;

That equates to around 1/230, which is very similar to the 1/200 quoted for scapa flow, which by the us definitions would appear to count as 'tech', although in the UK would be counted as 'rec'.
I'd be interested to know what the figures were for multi-day 60m+ diving, as there is often someone around with a bit of a 'niggle' by the end of the week, and rarely does it get reported anywhere

 

[mstudley]

:wacko: NOW HEAR THIS! NOW HEAR THIS!
TROLL SIGHTED ON THE PORT BOW! ALL HANDS TO BATTLE STATIONS! DIVE THE BOAT! I SAY AGAIN, DIVE THE BOAT! THIS IS NOT A DRILL!

THAT IS ALL!:mgun:

How is this a troll? I think a valid question is being asked. The posted even stated that it may be a touchy subject (for whatever reason) before asking the question.

Last time I checked a troll is someone who sits on a thread and has nothing useful to contribute (other than garbage posts).

People... relax...

-- Matt

 

[KLD]

About 3/4 of RGBM DB is from C & C Dive Team Operations
here at LANL (13 yrs). Most diving now is on RBs (heliox and
trimix). More OC earlier, and some nitrox and helitrox for
shallow (less than 150 fsw) recon and joint exercises still.
Most depths vary from 150 fsw down to 400 fsw. On OC, we
had hits years ago on nitrox deco in the 180 fsw range.
Deco repet hits on RPs occurred on helium rich mixes (200+
fsw) as mentioned. Team Ops can run for 3-4 days with 2 -3
deco repets a day depending -- only on helium these
days. Both RB and OC data from C & C is stored. And
rest of RGBM DB comes from contributions of selected
testors, special deep dives, NAUI Tec, but not rec diving.
Rec diving on air/nitrox is of interest in the category of many
closely spaced repets, high altitude, and RPs greater
than 50 fsw. Time permitting, we will open RGBM DB
to tech divers for their profiles. Process of how we
use RGBM DB is outlined in our books. Plus data from
other files, DBs, and sources.

RGBM DB is only interested in deep stop data, such as
what the USN Navy will be testing. That's RGBM-like.
There's enough shallow staging (Haldane) data around
from the past 80 yrs to suffice, and that skewing needs
be smoothed out. Deep stop deco stat analysis can't be
done properly with shallow stop data bases, or limited deep
stop data.

Niggles only recorded if neurologicals suggest impairment --
only one (or two) that I remember.

Stats from Scapa Flow (cold) are nested in DAN PDE
data, and are a set unto themselves. Something like
16 of 47 hits in DAN PDE come from Scapa. Stats there are
also reflected in USN deco tests in cold water. Cold
water is not your friend.

BW

That equates to around 1/230, which is very similar to the 1/200 quoted for scapa flow, which by the us definitions would appear to count as 'tech', although in the UK would be counted as 'rec'.
I'd be interested to know what the figures were for multi-day 60m+ diving, as there is often someone around with a bit of a 'niggle' by the end of the week, and rarely does it get reported anywhere