Effect of gas density while deep diving

[MomZo]

Just as a reminder, the latest Rec CMAS level, CMAS 3*, allows diver around the world to dive deep air up to 60m.
Everyday, some divers are doing so, and from my knowledge, there is no hecatomb due to this type of diving.

 

[grantctobin]

One day they’ll catch up on the more recent 20 years of science and safety.

 

[100days-a-year]

So are we going to have a huge retroactive loss of life for all those already completed dives? Asking for a friend. If not , then the stated dangers may be a bit overstated and more theoretical than practical.

 

[MomZo]

In many places in the world, there is no easy access to helium, without talking about the price which became really exorbitant, especially to dive in open circuit.

Moreover, when you dive in warm water with a good visibility, you don't experience the same impairment than diving in cold dark lakes by only few degrees.

I don't deny that diving helium is better for deep diving, and relatively safer than diving air, but I also think it is not a necessity when you dive deeper than 30m as it is recommended by several organizations (GUE to only quote one...)

 

[Storker]

the latest Rec CMAS level, CMAS 3*, allows diver around the world to dive deep air up to 60m.

...disregarding national limitations. Some countries' 3* certs "allow" for 60m. Others - AFAIK most European countries' - "allow" for 1.4 bar PO2, or 57m. A couple of the Scandinavian countries' 3* certs "allow" only 40m.

There isn't one universal CMAS standard. All CMAS certs must conform to CMAS' minimum standards, but each national Diving Association is free to impose stricter standards.

 

[jgttrey]

So are we going to have a huge retroactive loss of life for all those already completed dives? Asking for a friend. If not , then the stated dangers may be a bit overstated and more theoretical than practical.

This is nonsense. You could make this argument about almost any advance in diving safety. Risk exists on a spectrum. It isn't a light switch and the fact that something is safe 99% of the time doesn't mean you ignore the 1%. This like saying "my grandpappy smoked unfiltered Camels til he was 95 and it never hurt him."

Did you even read the study? The data is compelling and there are many accidents for which the cause is either unknown or poorly understood where gas density likely played a role. One of them, perhaps, is being discussed right now in another thread.

OC probably doesn't pose the same risk as CCR, I'll grant you. But the data justifies taking this seriously.

 

[AJ]

..... then the stated dangers may be a bit overstated and more theoretical than practical.

All deco theory is....well theory. We don't know exactly when you're going to get bend. You may get away with exceeding the theoretic boundaries many times, on the other hand you might get bend while staying within those theoretical limits on a bad day. All we know is that staying within those limits is statistically safer then going beyond them. In other words: you're less likely to get bend. It's all about risk appetite. In the end it's your call what you think is safe, there's no Scuba police that tells you what to do.

 

[100days-a-year]

So no, there won't be any retroactive deaths. Y'all could have just answered without all the histrionics. Glad to know all that historical empirical evidence isn't being ignored. I'll keep diving air and nitrox unless I'm going past 200' then.

 

[johndiver999]

For most people, I think the effects of narcosis are probably more of a concern than gas density at around 60 meters. There is a LOT of empirical evidence that some people can't handle the narc. If you have a decent regulator and don't swim too hard, I don't "feel" like the gas density issue is so important.

 

[Storker]

I don't "feel" the gas density issue is so important.

I prefer basing my choices on studies published in peer-reviewed scientific articles and what competent scientists are telling me, but to each their own.