Avoiding DCS with GF and MB settings

[100days-a-year]

Why don't you reread the post and point out where I disagreed with what you just said? And I emphasized the theoretical aspect as there are myriad "experts" who push one particular approach without even a basic understanding or ability to produce a single peer reviewed paper in support of their deco strategy de jour.

My post was based on between 100k and 200k dives between a couple dozen people with experiences over the last 50 years and comparing our outcomes.

 

[tursiops]

Why don't you reread the post and point out where I disagreed with what you just said? And I emphasized the theoretical aspect as there are myriad "experts" who push one particular approach without even a basic understanding or ability to produce a single peer reviewed paper in support of their deco strategy de jour.

My post was based on between 100k and 200k dives between a couple dozen people with experiences over the last 50 years and comparing our outcomes.

You should write up your experiences in a peer-reviewed publication, in support of your alternative view on DCS.

 

[100days-a-year]

Where exactly does this deviate from established findings,did you even read what I posted? Or was my spelling,punctuation and sentence structure so flawed it was confusing?

 

[scubadada]

It is my solely empirically based opine that recreatioal DCS is more a function of total time at depth and the diver's predisposition to DCS that any modern decompression " theory "
I dive 5 to 7 dives a day with a group of other commercial spearfishermen and those who stay longer on dives had far higher rates of incidents even if the total daily bottom time was equal , if that makes sense.

I must admit, I did not necessarily follow your post either. You have far greater exposure than most of us will ever have.

 

[stretchthepenn]

(deleted post...dunno how to do it right)

 

[tursiops]

It is my solely empirically based opine that recreatioal DCS is more a function of total time at depth and the diver's predisposition to DCS that any modern decompression " theory "

This is unclear as to whether you mean time on one dive or on a sequence of them over a (say) day. But I assume the latter, becasue of your next paragraph. Your implicaiton is that modern deco theory does not take into account time at depth, which of course is wrong.

I dive 5 to 7 dives a day with a group of other commercial spearfishermen and those who stay longer on dives had far higher rates of incidents even if the total daily bottom time was equal , if that makes sense.

If you are equating (say) 5 dives a day totaling 9say) 2h of bottom time, to one dive having 2h of BT, then modern deco theory clearly explains why the latter is a worse strategy.

Why don't you reread the post and point out where I disagreed with what you just said? And I emphasized the theoretical aspect as there are myriad "experts" who push one particular approach without even a basic understanding or ability to produce a single peer reviewed paper in support of their deco strategy de jour.

And I suggested you publish a peer-reviewed paper to support your suggestion that modern deco theory is unapplicable.

My post was based on between 100k and 200k dives between a couple dozen people with experiences over the last 50 years and comparing our outcomes.

Impressive, but modern deco theory is based on many more dives with many more people.

In another thread you are saying the EDGE and the ORCA and the Navy tables are just fine, all the new computers are useless (for your diving). Good luck with that.

 

[100days-a-year]

I thought it pretty clear that I implied total BT was safer in shorter doses and that using any modern deco strategy had less bearing on a DCS incident than physical predisposition and that first observation. I have no idea how anyone could misconstrue what I wrote to mean the opposite.
As far as the older computers, my luck seems to be holding out as I'm not dead yet .Nor do I have anything serious to report as far as DCS other than skin bends after a 30day 3 tank a day recreational vacation and a middle ear barotrauma that was also well within rec limits.

 

[Miyaru]

It is my solely empirically based opine that recreatioal DCS is more a function of total time at depth and the diver's predisposition to DCS that any modern decompression " theory "
...

There is no such thing as recreational DCS.
Ongassing and offgassing are physical processes based on pressure differences, regardless of a dive being recreational, technical or commercial. The same laws apply. The biological part makes the straight-forward physical laws more difficult: different tissues behaving each in their own way and several of those tissues are dependent on the behaviour of other tissues. How the biological part behaves, depends on the person performing the dive, not on the type of dive.

I feel pretty well versed and have a good understanding of diving where I'm at and just a tad beyond but I am wanting to learn more, advance my training and maybe even train in the future.

I like the shake the bottle description and have heard that before thru training.

What I haven't heard or read much about is the GF / MB settings and how it applies to folks - I've seen some dive profiles at a,b and c but....

51 years old, decent shape but I smoke, maybe I shouldn't be at MB zero. I'd just rather understand that now verses a physcian telling me that thru an intercom.

If you want a good explanation of how gradient factors influence the gas model, watch Dr. Neal Pollock - decompression stress, and Simon Mitchell - decompression controversies. And read the book Deco for Divers.

Really short explanation:
There's quite a bit of history leading to all this, starting at the beginning of the last century. Haldane used goats to determine when bubbles formed in different tissues. During the sixties, Workman used all this data and determined for each of those tissues a maximum value of gasloading. In the nineties, Bühlmann created a gasmodel with 16 compartments, simplifying all tissues in a mathematical way (a compartment does not equal a tissue!). Each compartment has a different speed for ongassing and offgassing, and a Maximum-value of supersaturation.
So the idea was, that if you stayed below the M-value, no bubbles would form. Didn't work for everyone. New bright minds introduced the bubblemodel, which looked much better, with shorter decompression times. Didn't work for everyone either. Back to the gas model, but now with some modifications that makes the gasmodel behave a bit like a bubblemodel. Gradient Factors determine where your first stop will be and keep you away from that M-value in the original Bühlmann model.
Does this work for everyone? We don't know (yet). But science progresses, knowledge increases and several decompression specialists keep presenting new study results. Places like this board are perfect to discuss and criticize those results, sometimes in notorious ways.

 

[100days-a-year]

Let me use smaller words for you.
DCS in a sinvle gas recreational dive setting with dives lasting less than NDL.
As opposed to dives with planned decompression, multiple gasses or overhead .

 

[ChuckP]

There is no such thing as recreational DCS.
Ongassing and offgassing are physical processes based on pressure differences, regardless of a dive being recreational, technical or commercial. The same laws apply. The biological part makes the straight-forward physical laws more difficult: different tissues behaving each in their own way and several of those tissues are dependent on the behaviour of other tissues. How the biological part behaves, depends on the person performing the dive, not on the type of dive.

If you want a good explanation of how gradient factors influence the gas model, watch Dr. Neal Pollock - decompression stress, and Simon Mitchell - decompression controversies. And read the book Deco for Divers.

Really short explanation:
There's quite a bit of history leading to all this, starting at the beginning of the last century. Haldane used goats to determine when bubbles formed in different tissues. During the sixties, Workman used all this data and determined for each of those tissues a maximum value of gasloading. In the nineties, Bühlmann created a gasmodel with 16 compartments, simplifying all tissues in a mathematical way (a compartment does not equal a tissue!). Each compartment has a different speed for ongassing and offgassing, and a Maximum-value of supersaturation.
So the idea was, that if you stayed below the M-value, no bubbles would form. Didn't work for everyone. New bright minds introduced the bubblemodel, which looked much better, with shorter decompression times. Didn't work for everyone either. Back to the gas model, but now with some modifications that makes the gasmodel behave a bit like a bubblemodel. Gradient Factors determine where your first stop will be and keep you away from that M-value in the original Bühlmann model.
Does this work for everyone? We don't know (yet). But science progresses, knowledge increases and several decompression specialists keep presenting new study results. Places like this board are perfect to discuss and criticize those results, sometimes in notorious ways.

I really appreciate the links - I need the time to read and watch them, later this week or tomorrow night - so dang busy.