Ad Hoc Deep Stop Prescriptions

[BRW]

Folks,

The business of "P/1.6", "halving", and "gradient factor" rules
for juxta-positioning deep stops (first and following afterward)
are all ad hoc measures imposed on Haldane deco. Sometimes
they work for very limited diving and ranges, but in general
they are without real physical basis. They are attempts to
get a dissolved gas (only) algorithm (Haldane M-values) to
mock up bubble dynamics. And such rules are not self
consistent for diving. They are also risky when they miss
requisite deeper stops, but give shorter overall deco in the
shallow zone.

They are a poor way to mock phase dynamics when dual
phase tables, meters, and software are now available to
do this self-consistently over a whole dive profile.

Diver, beware.

More on same in earlier posts/threads.

Bruce Wienke
Program Manager Computational Physics
C & C Dive Team

;-0

 

[MonkSeal]

BRW once bubbled...
They are a poor way to mock phase dynamics when dual
phase tables, meters, and software are now available to do this self-consistently over a whole dive profile.

OK. It's pretty clear that using dual phase tables and software (like new version of GAP which includes RGBM) is recommended. Also, RGBM computers (like Suunto) can be recommended to recreational divers (what do you think about it ?).

But my main questions are:
1. What do you think about recreational tables ?
2. Do they need improvments ?
3. Will it make them too complicated for average diver ?
4. How much differences would be between tables based on RGBM and US Navy based tables for shallow depths ?

Thanks
MonkSeal

 

[MikeFerrara]

BRW,

I know about the NAUI tables (though I'd have to look for a source) but what software and computers (multi-gas and trimix)contain a full RGBM implementation?

 

[BRW]

MonkSeal and Mike,

Right on. Thanks.

Here's some info on both sets of questions.

1) -- deep stops for recreational no-deco diving are safety
stops, and the 1/2 rule holds up fine in this regime.
This is a coupled rule for the new NAUI Rec Tables
and it has been correlated in RGBM and by Bennett at
DAN. Plus Marroni. Plus others. It extends to ALL
recreational Tables, RGBM, Navy, etc that we use.
The rule is "one minute at half the bottom depth"
Remember, this is for recreational, no-deco diving;

2) -- RGBM Rec Tables and Haldane based Rec Tables are
the same as far as NDLs. For repets, reverse profile,
and multiday diving, they diverge, because bubble
dynamics enter the RGBM Tables (even for rec diving);

3) -- big differences, of course, between Haldane (Navy, etc)
and RGBM deco Tables;

4) -- NAUI RGBM Tech Tables available at NAUI Hdqts. Also
NAUI RGBM Rec Tables;

5) -- Or, RGBM Tec Tables available at website, RGBMdiving.com
Go there for any Tables you want;

6) -- plus info on full up RGBM, and Haldane modified RGBM
(for rec diving with repets, reverse profiles and multiday
modifications);

7) -- full up RGBM is in EXPLORER deco meter, and in testing
phases for release by Mares, Dacor, and Zeagle also;

8) -- full up RGBM software offered by GAP and ABYSS (plus
coming out at RGBMdiving.com);

9)-- modified RGBM is in Suunto, Mares, Dacor, Plexus, and
unnamed (here) deco meters;

10) -- new book "Reduced Gradient Bubble ModeL In Depth"
by Best Pubs spells out all about full RGBM, modifed RGBM,
validation and testing, comparative phase vs Haldane
staging, material properties, math (read past it?),
statistics, history of deco models, deep stops,
helium mixes, staging strategies, field trials, plus other
stuff;

11) -- or go to website RGBMdiving.com for same info as bullet
just above, and all other bullets actually;

12) -- the Deep Stops & Modern Deco Strategies Wkshp at
Tampa last February gave a resounding thumbs up
to deep stops (tec and rec) based on data, experiments,
theory, and field tests.


Did I catch it all, MonkSeal and Mike? If not, pulse me back.

I have some quality time left for a few more days.

Regards,

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

 

[BigJetDriver]

MikeFerrara once bubbled...
BRW,

I know about the NAUI tables (though I'd have to look for a source) but what software and computers (multi-gas and trimix)contain a full RGBM implementation?

Mike,

For the NAUI RGBM tables, try:

Timothy O'Leary
Director / NAUI Technical Training Operations
(956)-761-7986

Here: <www.nauitec.com>

I'm ordering a copy through him. His office is in South Padre Island, Texas.

As for the RGBM computer, the Hydro-Space Explorer offers full-up
implementation, trimix, and constant PPO2.

Here: <www.hs-eng.com>

When you give HydroSpace a call, tell Gene I said "Hi!"

Rob

 

[BRW]

Tech Folks,

As Rob points out, NAUI RGBM Tech tables are available
thru Tim O'Leary, Director NAUI Tech Ops (Nauitec@aol.com)
And also from NAUI Hdqts in Tampa.

There are some 17 sets available, and you can see the list
at NAUI Tech website, and NAUI Online.

Other RGBM Tech Tables are available at RGBMdiving.com,
that is, air, nitrox, heliox, helitrox, trimix, and constant
ppO2 for same. Some are precalculated and can be
downloaded (standard for tech apps). Others can be
provided. So are field testing data, vaildation, info in general,
and Table rules.

Thanks,

Bruce Wienke
Program Manager Computational Physics
C & C Dive Team Leader
ut:

 

[DeepTechScuba]

Bruce,

Thank you for your fascinating replies. I always learn something when I read an article written by you.

You mentioned the Abyss software. And you did not mention DecoPlanner.

For relatively shallow technical applications, such as 400 fsw or shallower, I thought DecoPlanner had a pretty good reputation. However every time I mention deco software to a technical diving course director, I get the same response of "Abyss."

What are your thoughts on the reliability of DecoPlanner compared with Abyss?

Thanks again.

 

[MikeFerrara]

Thanks Bruce and Rob.

 

[O-ring]

DeepTechScuba once bubbled...
Bruce,

Thank you for your fascinating replies. I always learn something when I read an article written by you.

You mentioned the Abyss software. And you did not mention DecoPlanner.

For relatively shallow technical applications, such as 400 fsw or shallower, I thought DecoPlanner had a pretty good reputation. However every time I mention deco software to a technical diving course director, I get the same response of "Abyss."

What are your thoughts on the reliability of DecoPlanner compared with Abyss?

Thanks again.

But, IMHO, apples and oranges. Decoplanner is a dissolved gas model with gradient factors and anything running RGBM is a bubble model. BRW's first post is a pretty good summary of his views on the two models.

 

[BRW]

DeepTechScuba,

Good question.

My answer about Decoplanner and all Haldane based
algorithms with "deep stop knobs" using arbitrary rules
is the same -- beware because you don't know how to put
deep stops, and time at deep stops, into Haldane staging
correctly, nor self-consistently. No slurs directed at
Decoplanner by saying so -- the problem is Haldane deco.
And "deep stop knobs" -- like gradient factors, halving,
P/1.6 and others unsupported, or field tested.

Get GAP or ABYSS with phase RGBM. Or get the
the NAUI Tech Tables, or go to RGBMdiving.com and
generate your own, use what's there, or combos of
all of the above.

BTW, I am NOT on the GAP and ABYSS payroll in any way.
Think you all know this.

If you buy the EXPLORER (Hydrospace) deco meter, it has
an RGBM simulator. Paul mentioned it a few threads ago.
And is having "fun" with it.

But I do know what's in RGBM -- data, testing, validation,
gas dynamics, principles, etc. And I know what's wrong with
Haldane for anything but single, bounce (no-deco) apps, or
long spaced repets. Rec diving, that is. And all phase models
(like RGBM) collapse to same for nominal rec diving.

Thanks for your comments too.

Regards,

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