Another Deco profile post.

[Remy B.]

I have a better picture now, it is more about the speed of On-gassing and controlling the Off-gassing speed on the slow tissues/compartments in order to not allow the bubbles to grow to big, ( between 12 in 6m ) with 50%O2 where the body is 1 bar out of its day to day normal living condition.

 

[lermontov]

I have a better picture now, it is more about the speed of On-gassing and controlling the Off-gassing speed on the slow tissues/compartments in order to not allow the bubbles to grow to big, ( between 12 in 6m ) with 50%O2 where the body is 1 bar out of its day to day normal living condition.

all compartments

 

[Remy B.]

all compartments

The concern appears to be in the Slow compartments according the NEDU study, if I understood right apparently they are the culprit of DCS-2

 

[jfe]

Maybe this will help you.

 

[victorzamora]

The concern appears to be in the Slow compartments according the NEDU study, if I understood right apparently they are the culprit of DCS-2

Slow compartments are what you're impacting negatively with deep stops. You're sacrificing slow-compartment loading for theoretically "controlling the growth of bubbles" which has been shown to not be accurate.

 

[Carl_F]

When I read the OP's question, it appeared to me to be a question about further subdividing the deco stop depth intervals as opposed to taking some amount of time from a shallower stop and applying it to a deeper stop. The concept is that the shallowest depth allowed during decompression is a continuum and discrete stops are just a convenient subdivision of that continuum. In concept one could have the algorithm / computer output the shallowest allowed depth at each time increment (1 minute, 30 second, 10 second, or 1 second intervals ... which is still a discretization of the curve) and the diver could follow the specific curve. A deco profile is just a discretization of such a curve (or rather most conservative of a family of curves) using convenient increments of depth and time.

Most deco software probably has options for depth and time step sizes. VPlanner (what I use) has minimum depth and time step sizes of 10 ft and 1 minute, respectively. There is no reason it couldn't be programmed for 6-inch and 2 second step sizes. But the utility of that fine discretization is questionable as the ability of a diver to control depth and time to that level of detail would be questionable (and impossible for my abilities currently.)

At least that's how I read the OP's question.

 

[lermontov]

@Carl_F yes you could but as you pointed out what would you benefit- in fact breaking it down to such fine intervals would be inefficient in regard to gradients of the slower tissues

 

[Carl_F]

@Carl_F yes you could but as you pointed out what would you benefit- in fact breaking it down to such fine intervals would be inefficient in regard to gradients of the slower tissues

Actually, I think it would be the most efficient ... just not practical. The gradients for the limiting tissue at that point in time would be maximized through out the deco profile. The step-wise deco profile maximizes the gradients upon first reaching the depth and then the gradient is gradually reduced over the stop time until the gradients for the limiting tissues for the next stop depth are acceptable. Then we go to that new stop depth where gradients are again maximized and slowly reduced as we wait at that depth. The continuum profile would theoretically maintain the gradients maximized the whole time. But at the expense of having to manage that profile every second ... a huge PIA.

 

[lermontov]

Actually, I think it would be the most efficient ... just not practical. The gradients for the limiting tissue at that point in time would be maximized through out the deco profile. The step-wise deco profile maximizes the gradients upon first reaching the depth and then the gradient is gradually reduced over the stop time until the gradients for the limiting tissues for the next stop depth are acceptable. Then we go to that new stop depth where gradients are again maximized and slowly reduced as we wait at that depth. The continuum profile would theoretically maintain the gradients maximized the whole time. But at the expense of having to manage that profile every second ... a huge PIA.

hmm you might be right - l need to go and do some checking

 

[victorzamora]

hmm you might be right - l need to go and do some checking

Just think it through with a thought experiment. Breaking stops into smaller time and depth segments (2seconds/6inches) means you can leave that stop sooner and ascend, because your ceiling no longer has to be 10ft above you but 6in. Your stop depth becomes 30ft when your ceiling becomes 29ft and stays that way until your ceiling reaches 19ft. If your stop depth changed at 29ft, you could deco at 29.5ft and then move up to 29ft when your ceiling moved up to 28.5ft.

If you had a stop resolution of 2 seconds and 6 inches, you'd be following the ascent curve closer than I would be at 1min/10ft. While I was still at 30ft for X minutes before ascending to 20ft, you'd be slowly ascending from 30ft to 20ft during that time.

I'm not saying it's better, and it's certainly not practical, but it would follow the GF-line closer than the standard 1min/10ft stop resolution.