Deco at 6m vs 3m times inversion

[Remy B.]

Any of you have heard something about experimentation regarding inverting the Deco time from 3m to 6m, considering that, the off-gassing is more faster as more violent at 1.3atm then at 1.6atm

for example, a deco profile tells you 12min at 6m and 19min at 3m, what about inverting this 19min at 6m and 12min or less at 3m, considering that bubble size suppose to stay a little smaller and a little more under control ( supposedly ) at 1.6atm theoretically

Or staying longer at 6-5m and omitting the 3m deco stop ?

What tissues/compartments may get affected or have been affected with this experiments

 

[PfcAJ]

[abstract] THE EFFECT OF FINAL OXYGEN DECOMPRESSION STOP DEPTH ON DCS RISK: 20 FSW VS. 10 FSW.

 

[lv2dive]

Personally, I try to stay away from violent decompression if at all possible.

For dives with enough deco to sneeze at (30 minutes or more) I typically do a 10' stop. I have learned to listen to my body over the years, and that means:
- I always come up very slowly from 20' and 10'
- I listen when my body (typically my shoulder or knee) tells me I need to spend more time at the last stop

 

[stuartv]

Personally, I try to stay away from violent decompression if at all possible.

For dives with enough deco to sneeze at (30 minutes or more) I typically do a 10' stop. I have learned to listen to my body over the years, and that means:
- I always come up very slowly from 20' and 10'
- I listen when my body (typically my shoulder or knee) tells me I need to spend more time at the last stop

Are you talking about doing deco on 100% Oxygen or something with some N2 in it?

The THEORY is that deco on 100% is the same whether you're at 10' or 20', right? So, I'm asking if you have noticed something in practice that is different than what the theory predicts.

 

[PfcAJ]

I do the bulk of oxygen time at 20ft.

I find a slow ascent from 20 to the surface to be beneficial, and that usually turns into 'stops' at 15, 10, and 5.

 

[DevonDiver]

There are varied factors to consider; not least oxygen considerations (ppO2/OTUs/CNS%).

 

[Kevrumbo]

If you're on 100% whether you make your last stop at 20', 10', 2' or 0' (you breathe the O2 on the surface for a while) makes no difference in terms of how quickly you will offgas, since the inspired gas contains no inert gas of any kind. Therefore, the gradient is the same, for all intents and purposes, at all three depths, as equilibrium is a zero PP of Nitrogen (and Helium, if you were diving Trimix.) (Critical tensions, however, may be exceeded at shallower depth if you haven't spent enough time earlier doing the initial profile of the deco! [i.e. doing the profile times at deep stops and intermediate deco stop mixes like 50% at 21m/70' for example]).

While tissue gradients may not fluctuate between 20' and 10' on 100% O2, tissue tensions certainly still do. Theoretically, of course, as long as you're at 20' long enough to satisfy your model, it does no harm to do the remainder of your time at 15' or 10' or wherever's below the ceiling. Realistically, you're going to have bigger bubbles and more bubbles doing 20' and 10' stops than if you'd simply stayed at 20' the whole time. And we know it's harder to eliminate any undissolved gas, much less larger bubbles of it, than it is to off gas dissolved gas - thus, there's a theoretical efficiency case for doing the whole thing at 20'. But absent truly insane seas, I'll take the lower CNS loading for decos much past 2hrs. Last Deco Stop Depth, Oxygen Window, and Deco Efficacy

 

[Remy B.]

Thanks guys, that is what I was thinking.

Are you staying as well longer at 30ft /10m or there is a fast tissue/compartment that start on-gassing at that depth ?

 

[PfcAJ]

Thanks guys, that is what I was thinking.

Are you staying as well longer at 30ft /10m or there is a fast tissue/compartment that start on-gassing at that depth ?

I don't stay long at 30ft when there's the worlds most efficient deco gas 10ft above me.

 

[Germie]

100% is the most efficient decogas. But you will see in decoplanners that using on long decos a 80% or a 100% makes no difference. But I prefer a 100% over the 'disadvantages' as breaks and the higher cns.
My last decostop is at 6m, not at 3. Why? 3m is a problem in waves, on ccr 6m is easier than 3m. After the deco, then go from 6m to surface with 1m/minute.