Deep diving advice that goes against conventional thought?

[DaleC]

I may be speaking out of turn but I understood the comment to suggest that someone new doesn't learn RB and mixed gas all at the same time. First you learn to use the RB, then you learn mixed gas; or vise versa. I suppose if you already have a solid foundation in mixed gas diving that part of the theory wouldn't need to be learned, just how to do it with the RB.

With that in mind, could someone with OW OC air only take a mixed gas RB course, or would some prerequisite knowledge of mixed gas/decompression theory be expected.

 

[tomfcrist]

Entry level cert using trimix from the start, yes.

Right, but that card is not even close to a deep CCR cert. From 160 with less than 15 minutes of deco obligation (on CCR) the most you would need is a single 80 of air for bailout...and maybe some O2 to accelerate deco. The point Pfc was trying to make is that he thinks you need a bunch of OC time doing gas switches in order to do it on CCR...which is baloney, because gas switching isn't exactly rocket science.

 

[PfcAJ]

You sure have cavelier attitude about something that has killed a lot of people. Switching to the wrong gas is the number one recurrent theme in technical diving fatalities.

 

[kr2y5]

Switching to the wrong gas is the number one recurrent theme in technical diving fatalities.

Pardon my ignorance, but I have always wondered why this is happening, assuming that the victims have taken basic precautions like marking tanks, do you have a theory? I am not trying to imply here anything, just asking... I am simply curious what might be the likely reasons (assuming that narcosis is not a factor).

 

[PfcAJ]

In a nutshell it comes down to poor tank marking, poor procedure, non adherence to procedure. The non adherence to procure comes up mostly when a diver is stressed, task loaded, narced, or complacent (maybe all of them).

 

[100days-a-year]

Because it's normally an emergency or unplanned situation.Task loading on RBs is higher to start,add in a little exitement and it's easy to see it escalate to the point fatal mistakes are made.

I see more reports of RB deaths than OC in the realm of fully certified and qualified deep or penetration divers.Is this the general concensus or do I just see those reports?Not that RBs hold much interest,I spearfish 90% of time.

 

[DaleC]

Are RB divers bailing out to multiple mixes to the same degree? I see part of the complexity of deep OC dives being the physical complexity of managing numerous bottles of varying gasses, some of which will or will not kill you at some point during the dive.

 

[ajduplessis]

Pardon my ignorance, but I have always wondered why this is happening, assuming that the victims have taken basic precautions like marking tanks, do you have a theory? I am not trying to imply here anything, just asking... I am simply curious what might be the likely reasons (assuming that narcosis is not a factor).

Example: Diving to 300 ft+ is going to require at least 4 stage (3 deco and 1 bailout) for OC dive, and I would assume the same would apply for CCR. At ~ 300ft every 60 seconds you spend at depth will result in 10min additional deco to give you an idea of time pressures. When things go well, according to dive plan, then ascending and making the switches is rather easy for the seasoned tech diver. Any slight delay or failures add extreme task loading pressures and in conjunction with the already rapidly increasing time pressure (additional deco), things tend to go south.

The stressed diver will make mistakes and putting the wrong gas in your mouth during a stressful period is very, very, very easy. Many experienced divers have died this way. Procedures, self rescue, skill and common sense all get tested to the extreme when real pressure is applied.

Taskloading above the water is very simple.....

 

[DCBC]

Are RB divers bailing out to multiple mixes to the same degree? I see part of the complexity of deep OC dives being the physical complexity of managing numerous bottles of varying gasses, some of which will or will not kill you at some point during the dive.

Bailout is seldom required. I've been diving a RB for 43 years and have only required to bail-out three times. (equipment malfunction). As EMs occur less and less (better technology) this may be less of a consideration than it once was. Most often bail-out is only required for training purposes.

This of course is complicated in a decompression situation. The diver can elect to place decompression bottles at various depths to avoid carrying them with him (only carrying one travel gas based on the deepest depth). As I mainly dive enclosed environments, I opt for this option most of the time.

There is theory and there's practice. Each diver must elect a dive plan which s/he accepts and assume the degree of risk involved. This is dictated by personal choice and in-light of the diving conditions present and the complexity of the dive. There is no such thing as a perfect plan for all circumstances and *hit happens. If you want ultimate safety: don't dive a RB, don't dive deep and better still, just stay out of the water.

 

[tomfcrist]

You sure have cavelier attitude about something that has killed a lot of people. Switching to the wrong gas is the number one recurrent theme in technical diving fatalities.

I do not have a cavalier attitude. People that switch to the wrong gas either have no training at all or completely ignored thier training. 100% of those fatalities are complacency related, not experiance related.