"Riding your Computer Up" vs. "Lite Deco"

[scubadada]

So, the effect of (percieved) over-zealous algorithmic conservatism is creating a scenario whereby computer users are provoked into second-guessing, or disregarding entirely, the no-stop limits provided by their instrumentation?

Advanced divers are a relatively self-selecting demographic. Those with truly significant experience develop an intimate understanding of their personal relationship with factors like DCS, narcosis, O2 toxicity, task loading and stress management. They limit accordingly and prudently...even if/when such limits are beyond the 'norm' thresholds.

The danger for lesser experienced divers, especially when faced with human factor failings, dive agency marketing hype, a surplus of dive information and superficial peer empowerment from social media, is that they can easily over-estimate their physiological relationship with hyperbaric issues... and mistakenly select themselves for diving thresholds that can damage them.

Some of us never second guess or disregard our computers.

I agree with the rest. It is the lesser experienced group that more often does not do light deco, but, rather, makes a mistake and ends up in deco.

 

[bumcikaz]

Hey bumcikaz: I didn't do any 130' dives in Maryland. I'm a somewhat recent transplant to MD. I'm a southern boy originally, so all the dives I was talking about were in the Gulf of Mexico. With that said, there are several 130' + sites out here. Off the MD/Delaware coast there is the Marine Electric at 125ish and the Redford at 140'. I haven't dove these wrecks yet, but hoping to hit them in 2017.

Marine electric is about 120 and radford 130 to the sand
I crew on a dive boat in OCMD

 

[Lorenzoid]

I didn't read the whole thread, but I don't think that thread substantiates @halocline's statement that all the major agencies define solo as something other than OW recreational diving. Or I missed it in that thread.

I noted the thread only because it represents a recent discussion in which reasonable minds seemed to disagree.

 

[DevonDiver]

From my perspective, it's most often the less experienced group that starts pushing things.

How we define 'experienced' is, of course, very relative.

 

[DevonDiver]

Only by the definition of US agencies. BSAC teach it as part of the (AOW/RD) equivalent.

Maybe my memory is getting bad, but as a (former) BSAC instructor, I don't ever recall "being taught" decompression diving.

Yes, the 88' tables progressed into deco profiles... and I learned how to plan dives using those tables (as I also learned with PADI) tables... but there was no specific instruction on decompression techniques, ascents etc.

Given that 88' tables allow a diver to spend a maximum of 26 minutes at 51m/167ft, (stops are 3 at 9m and 18 min at 6m) that's one heck of a dive... given zero refined and extended deco training...

Its defensible only in respect to the club environment allowing certain peer assessment and moderation of diving scope.

Many divers could benefit from more peer assessment and diving scope moderation.

 

[scubadada]

Maybe my memory is getting bad, but as a (former) BSAC instructor, I don't ever recall "being taught" decompression diving.

Yes, the 88' tables progressed into deco profiles... and I learned how to plan dives using those tables (as I also learned with PADI) tables... but there was no specific instruction on decompression techniques, ascents etc.

Given that 88' tables allow a diver to spend a maximum of 26 minutes at 51m/167ft, (stops are 3 at 9m and 18 min at 6m) that's one heck of a dive... given zero refined and extended deco training...

Its defensible only in respect to the club environment allowing certain peer assessment and moderation of diving scope.

Many divers could benefit from more peer assessment and diving scope moderation.

That would exceed my definition of light deco

 

[boulderjohn]

The danger for lesser experienced divers, especially when faced with human factor failings, dive agency marketing hype, a surplus of dive information and superficial peer empowerment from social media, is that they can easily over-estimate their physiological relationship with hyperbaric issues... and mistakenly select themselves for diving thresholds that can damage them.

Over the years, past threads have pointed out that in a typical scuba course, we spend a lot of time dealing with the dangers of decompression sickness. As I mentioned earlier, the way we taught and used tables emphasized the danger of exceeding NDLs for even one minute. I was teaching a DM class, and when we talked about this, they were amazed--they always thought something dreadful would happen to them if they strayed into the land of deco for a minute or two. In contrast, although we do teach the dangers of rapid ascent, and we do mention lung overexpansion, and we do say don't hold your breath, the amount of time we spend on that is minimal compared to the amount of time we spend on DCS.

Scuba fatality statistics are just the opposite. It is extremely rare for a recreational diver to get DCS, and it is even more rare for that diver to die from it. On the other hand, a joint DAN/PADI study on scuba fatalities determined that the number one triggering event for a fatality (other than coronary health issues) was a panicked ascent to the surface leading to lung overexpansion. Often it followed an OOA incident, but other times the reason for the ascent was not known.

I briefly mentioned the dive buddy I had who made a panicked ascent when he saw his computer was getting near deco. I wonder how many fatalities were caused when people saw they had reached their NDLs and had to get to the surface in a hurry to prevent the horror of straying into deco.

 

[Edward3c]

Maybe my memory is getting bad, but as a (former) BSAC instructor, I don't ever recall "being taught" decompression diving.

Yes, the 88' tables progressed into deco profiles... and I learned how to plan dives using those tables (as I also learned with PADI) tables... but there was no specific instruction on decompression techniques, ascents etc.

Given that 88' tables allow a diver to spend a maximum of 26 minutes at 51m/167ft, (stops are 3 at 9m and 18 min at 6m) that's one heck of a dive... given zero refined and extended deco training...

Its defensible only in respect to the club environment allowing certain peer assessment and moderation of diving scope.

Many divers could benefit from more peer assessment and diving scope moderation.

Hi DD,

The current Sports Diver syllabus requires for SO3 the instructor to teach diving with planned deco stops. Last Saturday I took a student through the gas planning requirements for a 38m dive of 28 min bottom time. We then did the runtime, including stops, at a much shallower depth. What I was looking for was getting to the stops on time and maintaining buoyancy during the stops.

 

[DevonDiver]

Thanks Edward. So what's, now, the difference between that SO3 deco training and what divers would receive on the tech programme?

 

[DevonDiver]

It is extremely rare for a recreational diver to get DCS,...

Honest question. How many cases of DCS occur per annum, on average?

Don't worry about the issue of denial/non-treatment... just how many recreational divers are medically diagnosed with DCS of some form in a year.

Also don't worry about 'relative' statistics or 'rareity' ... because it's all too easy to think 1:10,000 isn't a lot. Whereas 10,000 cases a year might easily seem like a lot..

Seems to be a lot of multi-million dollar hyperbaric chambers around the world in popular diving locations... if DCS was so rare?

..and it is even more rare for that diver to die from it.

Yes, hyperbaric treatment is pretty effective in most instances.

On a personal note, I'm much more concerned by severe and debilitating non-fatal consequences of DCS. Losing the capacity to form an erection for the rest of my life doesn't sound like a consequence I'd want to accept for those 'few extra minutes' on a dive.

I wonder how many fatalities were caused when people saw they had reached their NDLs and had to get to the surface in a hurry to prevent the horror of straying into deco.

Not many I'd think. DCS is a very intangible, non-instinctive risk psychologically. There's no direct 'trigger' to our fight or flight instincts. Very unlike, for instance, having no breathing air, flooding a respiratory passage with water, or even seeing predatory marine life.

A decision to ascend quicker than optimally due to numbers on a computer screen is an error in comparative risk analysis. It's an intellectual process, albeit a flawed one, not an innate self-preservative reaction.

I agree that scare mongering about DCS is irresponsible. As noted, it can lead to flawed decision making.

At the same time, it'd be equally irresponsible to underplay the potential consequences of insufficient off-gassing on ascent from dives. That could also lead to equally flawed decision making.

I think it's erroneous to argue for less decompression education based on, as you say, low decompression accident rates.

It sounds, on the face of it, that the education works... and lowers DCS incident rates.

If other issues cause a higher proportion of incidents, then there's reason to suggest that more education and/or higher standard training should be necessary to comparatively lower those type of incident rates.

Why would it ever need to become an either/or situation?