Ratio deco for ccr?

Daffy said:
Unfortunately no one has been able to help the OP out with a solution to his problem, a problem that many of us share. It can be difficult to predict deco when on a multilevel cave dive. Maybe we should just start a separate thread for that…:sarcy:
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Its not actually. If you've got a long cave dive, then the average depth works pretty well. You're dealing mostly with slow compartments then, and the average of driving gradient is going to work pretty well to approximate the shape of the curve since you'll tend to be far from equilibrium but moving slowly towards that equilibrium. A linear approximation will be fine. One gotcha is that if you have a dip down at the end of the dive you'll start to load faster compartments and need to decompress those with deep stops driven more by your max depth there rather than the average depth for the whole dive.

Where depth averaging gets bad is on profiles where you've got a max depth of 170 foot and a 100 foot average for 20 minutes, which is very spiky and dominated by loading and unloading fast compartments.
 
And Rodney King had the audacity to ask "why can't we all get along"! C'mon Rodney, take a look around. :worm:
 
I read this thread but didn't find anything close to an answer to the question.

Is there an answer that can be shared or not?

Apologies if I missed it, I did skip over everything that looked like manly banter.

Matt.
 
Could you please develop this average depth / slow compartments theory since i am unfamiliar with it. What depth/time range and fluctuations in profile are we talking about?

lamont said:
Its not actually. If you've got a long cave dive, then the average depth works pretty well. You're dealing mostly with slow compartments then, and the average of driving gradient is going to work pretty well to approximate the shape of the curve since you'll tend to be far from equilibrium but moving slowly towards that equilibrium. A linear approximation will be fine. One gotcha is that if you have a dip down at the end of the dive you'll start to load faster compartments and need to decompress those with deep stops driven more by your max depth there rather than the average depth for the whole dive.

Where depth averaging gets bad is on profiles where you've got a max depth of 170 foot and a 100 foot average for 20 minutes, which is very spiky and dominated by loading and unloading fast compartments.
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matt said:
I read this thread but didn't find anything close to an answer to the question.

Is there an answer that can be shared or not?

Apologies if I missed it, I did skip over everything that looked like manly banter.

Matt.
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Lamont had some input that was on topic. Clare ran away. Gloc is insightful, but OC.

I think you have to be a GEU insider to understand the knowing hints that were dropped about standard gases.

Generaly I find when people have a hard time describing somthing, they don't really know how it works.

After listning to adhearants glowingly describe RD over the years, and then explane the work arounds, I shall stick to my tables and SOP.

It seems most useful to those who do the same dives over and again.

Presentation aside, I am inclined to agree with most of what Monkey had to say. It may be a cultural thing, but it just rings true. When very bad things have happened to me I was never in a position to add up my phone number and multiply it by my postal code. I do always carry a bottom timer that averages my depth. I generally have tables, and I see patterns that, in the back of my mind inform me as to my general well being.

I would have liked an explanation to how a program that is based on a fixed FO2 also can work for a fixed PO2.

Interesting debate however.

Peter
 
What could be easier than having 2 computers on your wrist ?

One of which also being a ppo2 monitor...

Nothing wrong with learning some patterns and ratios which we are obviously cable and prone to doing as human beings

I'm much happier having something work out a precise (as precise as a deco model can be) answer for me

They are also very handy for multi level repetative diving and track cns and such very nicely and accurately


Sent from my BlackBerry 9900 using Tapatalk
 
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PeterN said:
Lamont had some input that was on topic. Clare ran away. Gloc is insightful, but OC
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It's probably smug, self-satisfied posts like that which have always deterred those that successfully pull-off all manner of dives using ratio deco from sharing the love.

I've seen countless internet threads about the subject descend into farce when it seemed that all was about to be revealed. It didn't help matters when Georgitsis started banging-on about Fibonacci numbers as if it was the two times table and things haven't improved since then.

Personally, I'd love to hear someone with Clare's experience explain what the process is, but I can understand why she 'ran away' as you so unhelpfully described it. Sadly, when people with Monkey's blinkered attitude are happy to pile-in with personal vitriol, the debate gets stifled before it can get going.
 
PeterN said:
Lamont had some input that was on topic. Clare ran away. Gloc is insightful, but OC.

I think you have to be a GEU insider to understand the knowing hints that were dropped about standard gases.

Generaly I find when people have a hard time describing somthing, they don't really know how it works.

After listning to adhearants glowingly describe RD over the years, and then explane the work arounds, I shall stick to my tables and SOP.

It seems most useful to those who do the same dives over and again.

Presentation aside, I am inclined to agree with most of what Monkey had to say. It may be a cultural thing, but it just rings true. When very bad things have happened to me I was never in a position to add up my phone number and multiply it by my postal code. I do always carry a bottom timer that averages my depth. I generally have tables, and I see patterns that, in the back of my mind inform me as to my general well being.

I would have liked an explanation to how a program that is based on a fixed FO2 also can work for a fixed PO2.

Interesting debate however.

Peter
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I think some knowledgeable people are backing off this thread (not saying i am one of them) because RD have been misinterpret so many times before on forums with the result of divers not having the whole picture getting them self in a position where they might risk getting bent.
The whole idea only really works if you adhere to all the parts of the philosophy which involves team diving, standard gasses etc in my opinion.
 
Igor said:
I think some knowledgeable people are backing off this thread (not saying i am one of them) because RD have been misinterpret so many times before on forums with the result of divers not having the whole picture getting them self in a position where they might risk getting bent.
The whole idea only really works if you adhere to all the parts of the philosophy which involves team diving, standard gasses etc in my opinion.
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If you think that's a problem why not give us the full gospel and see how many discipels you get?


/nils
 
I don't think I'd ever use it as I don't do stuff that#s no needed, I have a table and I can wing-it from that.

However I'd like to have seen it explained practically for CCR.

Matt.
 
PeterN said:
Generaly I find when people have a hard time describing somthing, they don't really know how it works.
Click to expand...

That or it really doesn't work all that well.

PeterN said:
After listning to adhearants glowingly describe RD over the years, and then explane the work arounds, I shall stick to my tables and SOP.

It seems most useful to those who do the same dives over and again.

Presentation aside, I am inclined to agree with most of what Monkey had to say. It may be a cultural thing, but it just rings true. When very bad things have happened to me I was never in a position to add up my phone number and multiply it by my postal code. I do always carry a bottom timer that averages my depth. I generally have tables, and I see patterns that, in the back of my mind inform me as to my general well being.

I would have liked an explanation to how a program that is based on a fixed FO2 also can work for a fixed PO2.

Interesting debate however.

Peter
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It has been an interesting debate, even if off topic for most of its course. I was hoping one of the anointed GUE members would have more directly commented towards your original inquiry. I'd like to know as well if it can be worked into a set PO2 paradigm, for academic reasons. In practical application however, I will march on with multiple computers and a brace of contingency tables.
 
DeepUnderground said:
What could be easier than having 2 computers on your wrist ?

One of which also being a ppo2 monitor...

Nothing wrong with learning some patterns and ratios which we are obviously cable and prone to doing as human beings

I'm much happier having something work out a precise (as precise as a deco model can be) answer for me

They are also very handy for multi level repetative diving and track cns and such very nicely and accurately


Sent from my BlackBerry 9900 using Tapatalk
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I am using RD as a "backup computer". I do not necessarily think there is anything wrong with your approach of using a redundant computer though as long as there is a reasonable underlying understanding of how decompression works. It´s just that i have been diving RD successfully for some time and i feel it works and i do not see the need for a second dive computer at the moment. Fair enough?

Decompression sickness is very very far down the list of concerns when rebreather diving for me. Breathing a toxic gas is on top of my list. This whole thread is rather useless in my view.
 
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