Which do you think is less dangerous at 160ft? Open-circuit air or CCR trimix?

[CG43]

If you join a project in shallow waters, you'll see how even at very shallow depth our mental abilities massively decrease. I did quite some projects in shallow caves (depth less than 10m) and, really, our problem solving abilities are extremely low compared to ambient pressure. Problem is that rec diving doesn't involve problem solving, so we don't realise it. Until we have an accident and we need to solve the unexpected problem.

This is very interesting !
Since cave is a strong influencing variable in addition to deep, I would initially think to avoid mixing better.
It will certainly interest many here if you can write something about the structure and results of your study.

 

[ginti]

This is very interesting !
Since cave is a strong influencing variable in addition to deep, I would initially think to avoid mixing better.
It will certainly interest many here if you can write something about the structure and results of your study.

They were not *my studies* - just geological projects led by other divers or scientists. So I have no results to share about cognitive performance, sorry for that

 

[justinthedeeps]

People who plan dives to 50m and then go to 60m are careless and have no discipline. I’ve never done it and actually never could as I always plan to the deepest part of a wreck. In the case of the Aikoku Maru I’d plan the dive to 64m. I think that poor discipline might be a result of blindly following a computer. I’ve left some nice stuff on the bottom as I ran out of time to get it on a bag.

Tour/guide/company/instructor/agency polices are rightly strict about things like this, and of course you are right. But SCUBA like all 'outdoor adventure' pursuits has been an exploratory activity for a very long time. Cruising around at 55 metres on air was once (even recently) also a standard. You just prefer a different standard now.

While most of us agree that it is suboptimal and a serious safety risk now that additional options are available, it may still well be some other person's plan. Totally valid to discuss what we reckon is objectively safer given today's options and training opportunities.

People widely used to climb 8000+ metre peaks without supplemental oxygen, and apparently some still do, whether or not (Training Agency That Makes Sensible Rules for its Customers and Members) recommends it

Now how about, is it a safety risk to choose a CCR for a 15-metre (50ft) dive? With all those additional possible failure/risk scenarios? The answer may well be yes, but person-to-person variation in protocol and decision making may still make more difference than the CC/OC comparison.

 

[Wibble]

Now how about, is it a safety risk to choose a CCR for a 15-metre (50ft) dive? With all those additional possible failure/risk scenarios? The answer may well be yes, but person-to-person variation in protocol and decision making may still make more difference than the CC/OC comparison.

I'd choose the rebreather over OC for a 15m/50ft dive most of the time. Obviously if doing a cattle boat for a long 45min dive, then may as well blow bubbles. But if diving it by myself for a couple or three hours looking at pretty fish, the rebreather wins hands down.

Same with overheads. The rebreather's much more safe than OC as there's so many options should something fail. The only things that would drive me to use OC over CCR would be tight restrictions or a punitive carry to dive base.

Obviously rebreather divers have the option for either; OC divers have no other choice than OC.