RGBM Implementation

[ninjamuzo]

I am writing some deco software based on a modification on the approach used by Haldane to be used for very deep dives (Trimix) and I would like to do some comparisons with the RGBM deco model.

I have a couple of his books but the math while obviously elegant is difficult to decipher to the point where I can put it into a program.

Does anyone have a basic example of a program that implements RGBM for Trimix. It can be in any language. Once I see the underlying approach I would be able to extend that based on the materials in the books.

I have contacted Bruce Weinke directly but he does not give out any copies of his program(s) even the most basic ones.

I would of course credit anyone who helps if a paper comes out of this work.

Thanks in Advance
James.

 

[fldivenut]

Why do you want to reinvent the wheel?

Get a copy of this SW and save you some time on land and go diving!
www.gap-software.com
--A

 

[ninjamuzo]

You missed the point, I'm writing a new deco software system.

All of the current methodologies have led to a deco hit on the big dives 250m +. The exception was the last record 313m where the diver did not come up bent and requiring massive amounts of time in a Deco chamber. This is the system I'm putting into a program and want RGBM as one of the comparisons.

Following RGBM on a similar dive resulted in $40,000 worth of deco chamber time. I want to see the comparison and where the ascent ceiling I'm calculating is violated using other deco calculation methods.

 

[padiscubapro]

You missed the point, I'm writing a new deco software system.

All of the current methodologies have led to a deco hit on the big dives 250m +. The exception was the last record 313m where the diver did not come up bent and requiring massive amounts of time in a Deco chamber. This is the system I'm putting into a program and want RGBM as one of the comparisons.

Following RGBM on a similar dive resulted in $40,000 worth of deco chamber time. I want to see the comparison and where the ascent ceiling I'm calculating is violated using other deco calculation methods.

If you want the RGBM code youll have to fork over 5K us$.. besides RGBM is only valid to 160M or 180M, I dont remember the exact limit.. I do know one person who routinely does 150m dives using the agressive setting within gap without any problems but mostly on a CCR, on OC he usually only does 125m or so.

 

[ninjamuzo]

If you want the RGBM code youll have to fork over 5K us$.. besides RGBM is only valid to 160M or 180M, I dont remember the exact limit.. I do know one person who routinely does 150m dives using the agressive setting within gap without any problems but mostly on a CCR, on OC he usually only does 125m or so.

OK thanks for the info, in that case I'll keep working through the math and see what I can come up with on my own.

The theory should be valid to any depth as long as the ascent gradients are calculated correctly.

As you know the body does suddenly start behaving differently in terms of gas absorbtion at depths below 200m and what we come up with will be used at those depths.

 

[KLD]

OK thanks for the info, in that case I'll keep working through the math and see what I can come up with on my own.

The theory should be valid to any depth as long as the ascent gradients are calculated correctly.

As you know the body does suddenly start behaving differently in terms of gas absorbtion at depths below 200m and what we come up with will be used at those depths.

Ninja,

Pretty ambitious undertaking (from your email to me
about RGBM), and I hope you can come up to speed
on some 50 yrs of deco science and experience real
quick. And maybe get some diving experience in that
range (guess you said you were just starting a basic
trimix course).

Couple of simple things you should know:

1 -- there's much more to a 1040 fsw dive "than getting the
ascent gradients correct";

2 -- things like fluid shifts, ICD on gas switches, isobaric
slams, HPNS, plus depth effects on biomass etc
are not even theorized, much less tested;

3 -- RGBM is correlated with data down to 600 fsw,
and that's why GAP limits depths -- it has been run
down to 2000 fsw and reproduces sat schedules ;

4 -- Ellyat used RGBM on two dives down to 540 fsw
without problems (see Diver Net). Plus others
in the 800 fsw range from communications I
received from him over the past couple of years;

5 -- problems with bad gas switch strategies, like
deep switches to nitrox off trimix, will get
you in big trouble, and have nothing to do with
RGBM, or any other staging algorithm;

6 -- an article about ICD and Ellyat's dive to 1040 fsw,
plus strawman switch schedule plus matched
runtime RGBM schedule will be published in Advanced
Diver Magazine in the next issue;

7 -- theories are NOT "valid to any depth" because the body
is so complicated that we have only touched the
surface on mechanisms, and even a modern dual
phase deco model like RGBM is coarse grained;

8 -- gas transfer changes dramatically at depths as
physiological response varies, up and down;

9 -- bubble formation in the laboratory has been observed
to also change dramatically at 30 atm versus 1 - 10
atm, and we know nothing of micronuclei bubble
formation under exercise in the body at 30 atm
(buildup and elimination times, scales, sizes, etc);

10 -- RGBM is licensed for use in the professional
diving community only.


Regards,

BRW













2 --

 

[ninjamuzo]

Thanks for your comments.

Ambitious perhaps but an interesting exercise as well.

Advanced Trimix Diving actually.

On 2. The model/software I am working on is ironically with the guy who did the last dive plan for Mark (whom I have yet to meet) and will factor in isobaric counter diffusion 'slams' any anything else we can work out for that kind of extreme diving. We will also be looking at a theory behind ICD and if we can relate it directly back to some kind of relationship between the gases and the tissues.

On 5. Acknowledged which is the goal of the current research we are doing.

On 6. I subscribed to this a few months ago but have yet to see any copies.

On 7. Also acknowledged, but certainly true for most regular and even technical diving that the vast majority of people will ever dive to.

On 8. Also acknowledged.

On 9. And bounce dive data is also scarce

On 10. Not sure what you mean by this. The people I work and dive with are all Advanced Technical Instructors with thousands of dives behind them. They all work in the dive industry as professionals and the person I'm working with in these programs is an Engineer in addition to being an instructor. I am an instructor for PADI in Tec-Deep and was an IANTD instructor. Since I don't work in industry full time I doubut that I will become an Advanced Trimix Instructor myself but I have the training at least (ANDI/TDI course materials and Instructors).

If instead by professional you mean people who make money from writing Deco software or implementing them in dive computers like the VR3 then no, I don't fall into that category.

 

[Saturation]

You heard it direct from the RGBM maven, BRW. I am intrigued by what you think you can accomplish but it seems if you really have ideas to advance BRW's model, it would be most effective to hook up with him directly ... by convincing him in exacting detail what you have in mind, it would benefit the both of you directly if there is merit worth testing. It would save you a ton of time and avoid reinventing the RGBM wheel, and allows you to take off where BRW has left off. I would love to hear it here.

 

[ninjamuzo]

Actually the idea is to come up with a model that allows anyone to dive to 1000' and come back safely to the surface without a DCS or ICD hit. I have contacted BRW directly and also since then been in contact with others in the industry who have contrasting ideas on the validity of his model.

I have also since found out that the people I am and will be working with are somewhat at odds with BRW and while I am personally only interested in the purely technical side of the issue I will have back away from that one for a while.

The model we are working on was used for the last 1000' dive and the person concerned came back safely and in good health. Patrt of this has something to do with a solution to the ICD issue and we will be working on the mathematical support for the practical steps used.

The interest in RGBM was for comparison purposes. Part of our research will be looking at the underpinnings of that model particularly w.r.t. deep dives. I have now found a good set of abstracts on the medical and physiological side of that model and have noticed some similarities in them when compared with the simplified versions of the equations published in BW's books.

I have also found some people who will support me with a breakdown of the RGBM and similar models for reference. My impression from BW was that he was too busy for any kind of collaboration and he has enough on his plate on related issues.

Since it is conceivable that I will be acting in some kind of support role both in and out of the water for similar 1000'+ attempts I have a personal interest in making sure that the dive plans used work and are safe.

 

[Saturation]

Actually the idea is to come up with a model that allows anyone to dive to 1000' and come back safely to the surface without a DCS or ICD hit. I have contacted BRW directly and also since then been in contact with others in the industry who have contrasting ideas on the validity of his model.

I have also since found out that the people I am and will be working with are somewhat at odds with BRW and while I am personally only interested in the purely technical side of the issue I will have back away from that one for a while.

The model we are working on was used for the last 1000' dive and the person concerned came back safely and in good health. Patrt of this has something to do with a solution to the ICD issue and we will be working on the mathematical support for the practical steps used.

The interest in RGBM was for comparison purposes. Part of our research will be looking at the underpinnings of that model particularly w.r.t. deep dives. I have now found a good set of abstracts on the medical and physiological side of that model and have noticed some similarities in them when compared with the simplified versions of the equations published in BW's books.

I have also found some people who will support me with a breakdown of the RGBM and similar models for reference. My impression from BW was that he was too busy for any kind of collaboration and he has enough on his plate on related issues.

Since it is conceivable that I will be acting in some kind of support role both in and out of the water for similar 1000'+ attempts I have a personal interest in making sure that the dive plans used work and are safe.

Very good then, James, but what exactly did you have in mind that would make one dive to 1000' without issue? We have copies of Ellyatt's schedule, but no hard confirmation that this is indeed the schedule, and its very bubble model in shape with a need to modify some sections for further testing.

However, before you also close the book on this please discuss your ideas with a most amazing chap who goes by Departurediver in scubaboard.

http://www.diverssupport.com/

He has independently extend the thermodynamic model plus other bubble model equations to come up with a model very much like RGBM or VPM.

My plate is currently full in examining models but will get to Departure very soon.