Decompression Stop Guidelines - What we have to do if got deco alert?

[Diver-Drex]

@boulderjohn - you tell them not to drown. You've made the point a few times in other threads that clearing the deco obligation displayed by a computer may or may not be necessary for survival. Some people have been critical of your point. In this context the choice is clear - risk being bent vs drowning.
I think the broader point is that you shouldn't have accidentally violated your NDL in the first place. But if you're inclined to that oversight you're likely not paying attention to your spg. So you may end up having the make a choice of the lesser of two evils. A lot of survival situations come down to tough choices. Paying attention is a pretty easy choice to make.

 

[boulderjohn]

@boulderjohn - you tell them not to drown. You've made the point a few times in other threads that clearing the deco obligation displayed by a computer may or may not be necessary for survival. Some people have been critical of your point. In this context the choice is clear - risk being bent vs drowning.
I think the broader point is that you shouldn't have accidentally violated your NDL in the first place. But if you're inclined to that oversight you're likely not paying attention to your spg. So you may end up having the make a choice of the lesser of two evils. A lot of survival situations come down to tough choices. Paying attention is a pretty easy choice to make.

Please quote whatever I said that led to this response. I need the context. I don't know what you are talking about, and I don't know how to respond.

 

[lermontov]

Riding the computer, i.e. ascending and keeping 1 minute or so as the available No Stop Time, is far more aggressive to my mind than getting 5 minutes of deco and adding 3 or four minutes on at the end of the stop as a safety factor.

are you saying that on the assumption that your not having safety stop as well? or do you think its still more aggressive even with the safety stop- if so why?

 

[gfaith]

@boulderjohn

It would have been extremely unlucky at that point to have a catastrophic gas loss, extremely unlucky, but...but...what would I tell my students they should do in that case, and why should I not do it myself?

I am not sure if your question was rhetoric or not. But no buddy on ascent and no redundancy... Well on a wall dive recently in Roatan I told my buddy I wanted to bounce down to 100 feet, and my buddy/wife said she did not 65ish was fine with her. Well I went ahead and did the bounce and looked up at her and thought dang if she or I have a issue now we could be in trouble. So I zipped right up to where she was and got a fast ascent mandatory 1 minute deco in the process.. I know stupid . My lesson learned (for me) stay with my buddy and quit putting her in that situation. By the way she has the Deep Diver specialty she just didn't want to go there that day.

 

[The Chairman]

Paying attention is a pretty easy choice to make.

Indeed. The best response to having an incident is to avoid having one to begin with.

are you saying that on the assumption that your not having safety stop as well? or do you think its still more aggressive even with the safety stop- if so why?

It's definitely more aggressive and I would prefer to have a full ten minute safety stop if were to do this instead of my usual five. When PDCs started to become popular, the agencies saw the "cushion" provided by tables evaporate. Most of them dictated a full five minute safety stop if you were on a PDC. I still hold to that protocol because I feel so much better after the dive when I do that.

 

[lermontov]

It's definitely more aggressive and I would prefer to have a full ten minute safety stop if were to do this instead of my usual five. When PDCs started to become popular, the agencies saw the "cushion" provided by tables evaporate. Most of them dictated a full five minute safety stop if you were on a PDC. I still hold to that protocol because I feel so much better after the dive when I do that.

you may well right and im not disagreeing - id add on a few extra minutes too if was riding the NDL up -but im wondering what data is available to justify taking this position or is it subjective (ie i feel better)
Lets say an OW diver reads "stay within the NDL" and follows that to the letter, is there any literature "pre deco procedures training" to say that they should add on more minutes?

 

[The Chairman]

but im wondering what data is available to justify taking this position or is it subjective (ie i feel better)

This goes back to a talk given by DAN here in the Keys... in fact I think it was Dan Orr. He cited that many years ago, DAN used to differentiate between Type I and Type II DCS. While acquiring DCS was little more than statistical noise, if you had Type I, you were 98% likely to be a commercial diver and if you had Type II you were 98% likely to be a rec diver. Wow. Type II is a neural hit. So, if I'm going to do a stop that's going to make a difference then I'm going to address neural fluids which have about a five minute half time. So, five minutes is my minimum stop and if I have an issue on the dive, I try to double that. Most divers don't realize that getting out of the water is the most stressful part of your dive. You're struggling to pull all that heavy wet gear out of the water, sometimes in pitching seas as you waddle up the ladder and then to your seat.

 

[RayfromTX]

This old man realizes it. I'll ditch my pride and hand up my gear if I can.

 

[Diver-Drex]

@boulderjohn - this was from the planned deco on a rec dive thread.

Some people misunderstood some posts I made on this topic few weeks ago. In them, I said that I used a Shearwater computer in tech mode while doing recreational dives, and in that mode with the settings I use or technical dives, it will put me into deco when others are still within NDLs. I also said that when it puts me into deco, it is telling me I need to do a 1 minute stop--less than a standard safety stop. If I go a couple more minutes into deco, I get to stop for the full 3 minutes. I don't worry about it. The worst thing that could happen is that I might have a catastrophic gas loss while doing that stop (highly unlikely) and have to surface before it is done. Under those circumstances, I will almost certainly have no ill effects.

And from this thread.

It would have been extremely unlucky at that point to have a catastrophic gas loss, extremely unlucky, but...but...what would I tell my students they should do in that case, and why should I not do it myself?

In the context of this thread, how to handle unplanned deco, your point is spot on. There are likely several factors to consider; gas supply remaining, injury, worsening conditions, etc. that make getting out of the water a priority. A minute or two of deco obligation may not be the highest risk.

 

[RainPilot]

This goes back to a talk given by DAN here in the Keys... in fact I think it was Dan Orr. He cited that many years ago, DAN used to differentiate between Type I and Type II DCS. While acquiring DCS was little more than statistical noise, if you had Type I, you were 98% likely to be a commercial diver and if you had Type II you were 98% likely to be a rec diver. Wow. Type II is a neural hit. So, if I'm going to do a stop that's going to make a difference then I'm going to address neural fluids which have about a five minute half time. So, five minutes is my minimum stop and if I have an issue on the dive, I try to double that. Most divers don't realize that getting out of the water is the most stressful part of your dive. You're struggling to pull all that heavy wet gear out of the water, sometimes in pitching seas as you waddle up the ladder and then to your seat.

Working hard during the "Champagne Minutes" is never great. I'd much rather hang under the boat watching the fish and other divers for a little longer....

I also, where practical, will float on the surface by the ladder until I'm the last one aboard. The immersion effects on perfusion can't hurt.