Slow tissue on gas from stops

[rossh]

I thought I should point out something that has been badly misunderstood around here: slow tissue on gas in deco and ascent.

Slow tissue on-gassing exists in almost every plan and model type, right up to nearly the last stop. On gassing in ascent, exists all the time in all plans and all model types, right up to the point of full saturation.

Some people would have you believe this is unique to deeper stops, but in fact it exists everywhere in all ascents. The model formula properly account for this increase, so its not an issue.


Here is a GF 50/ 85 example, using EFX's dive calculator spread sheet.

Here the tissue values are shown at each incremental ascent step, and every cell from # 6 and beyond, is on-gassing at some point. The slow ones on-gas right up to the last stop.

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[tbone1004]

@rossh the question was never whether they were ongassing or not, but how many are ongassing vs offgassing and for how long

 

[rhwestfall]

subscribing...

 

[rossh]

@rossh the question was never whether they were ongassing or not, but how many are ongassing vs offgassing and for how long

As you can see in the example, They all on gas, right up to the point until they become the limiting ascent cell (where the stop occurs [blue boxes]). Then after that stop passes, the cell begins to off gas as the diver continues to following stop levels. This is the basic and standard behavior, common to all plans of all types and all GF levels,etc,etc,

The anti deep-stop sham you have been entertained with these past years, does not have unique on gassing, or even slightly different from the gradual levels and changes you see above.

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[tbone1004]

@rossh so what are you trying to prove with this? I haven't seen anyone who is knowledgeable enough to actually speak on this topic come out and say that slow tissues aren't ongassing during an ascent. It's all about how much they ongas and what the consequences of doing that are.

I would hardly call it a sham as those that have been working to disprove deep stops don't actually have any motivation other than ending a multi-decade debate amongst divers about which general ascent profile is the least unsafe for us, and doing it scientifically vs. theoretically

 

[Michael Guerrero]

I think this is what you would call a troll post. Deliberately stirring up controversy to sell more Vplanner and Ultimate Planner.

 

[tridacna]

Ross vs Simon - Round 10. All previous 9 rounds by clear decision to Simon. I wonder how this will work out...Hmm

 

[The Chairman]

I thought I should point out something that has been badly misunderstood around here:

Who misunderstood it? No one that I have known. Would you have us simply abandon all stops and pop quickly to the surface? This is why we wear PDCs or use tables: so we can make a reasonable SWAG.

Almost all people I know that have been bent have had neurological symptoms. Maybe all. I'm going to dive in a way that will ameliorate that possibility, including longer stops, especially the final stop. Most recreational divers will not log enough bottom time to worry about those mid to slow tissues. Dive in such a way to reduce your exposure to real risks: not imagined ones.

 

[rossh]

Who misunderstood it? No one that I have known. Would you have us simply abandon all stops and pop quickly to the surface? This is why we wear PDCs or use tables: so we can make a reasonable SWAG.

Almost all people I know that have been bent have had neurological symptoms. Maybe all. I'm going to dive in a way that will ameliorate that possibility, including longer stops, especially the final stop. Most recreational divers will not log enough bottom time to worry about those mid to slow tissues. Dive in such a way to reduce your exposure to real risks: not imagined ones.

Hi Pete,

Given how much artificial fussing has been made by some that we on gas in the deeper deco stops, I simply point out that it occurs everywhere, in all models and all plan types. For some people this will be news, and that distorted argument was enough to cause them to make limited deco choices.

Of course the underlying model formula fully address these changes, where ever they occur in the dive profile. Any notion that more manual stop adding is needed to compensate, is wrong.


Another myth that you touched on there Pete, is the one that we accumulate more residual tissue gas over several days diving. I showed that is not correct in graphs in this post. The real situation is our tissue pressures will level off after a day or so of repeated diving. The underlying cause of multi-day DCS events, does not involve a multi-day build up of tissue pressures, but would seem to be some other factor, yet to be explained fully.

 

[Diver0001]

I thought I should point out something that has been badly misunderstood around here: slow tissue on gas in deco and ascent.

Slow tissue on-gassing exists in almost every plan and model type, right up to nearly the last stop. On gassing in ascent, exists all the time in all plans and all model types, right up to the point of full saturation.

Some people would have you believe this is unique to deeper stops, but in fact it exists everywhere in all ascents. The model formula properly account for this increase, so its not an issue.


Here is a GF 50/ 85 example, using EFX's dive calculator spread sheet.


View attachment 448456

Here the tissue values are shown at each incremental ascent step, and every cell from # 6 and beyond, is on-gassing at some point. The slow ones on-gas right up to the last stop.

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Well.... we're making progress, I guess. I'm glad to see that the coin has fallen to the point that you understand that slower tissues can continue to on-gass during ascent, naturally as a function of depth and duration, as should be expected.

My expectations of how this thread will develop are not optimistic -- to be absolutely honest -- but before it goes down that road let me ask you a couple of sincere questions for clarification.

1) you now understand that slower tissues can continue to on-gass during ascent. Do you believe that they on-gass MORE during a deeper ascent than they do during a more shallow ascent?

2) Assuming you said yes to #1 do you believe that this higher tissue gas load should be taken into account by deco algorithms?

3) Do you believe that deep stops in essence result in a deeper ascent line that leads to more on-gassing of slower tissues? (referring to #1 and #2)

4) If you answered yes to #2 and #3 then can you understand why a deeper ascent line (resulting in more on-gassing) also requires more shallow time to release that gas again?

R..