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

[PEDiver]

Its done all the time,

Deep dive 50-60 m Deep Air course in Calabria | Diving Megale Hellas

The Deep dive Air course gives skills to practice dives breathing air within a maximum depth of 50 m or 60 m, with decompression stops with Nitrox 50.

www.megalehellas.net

Great, thanks for providing a dive center that I know to avoid. If you're teaching students how to dive air to 60m, then I want to stay as far away as possible.

 

[iliketopetsharks]

Its done all the time,

Deep dive 50-60 m Deep Air course in Calabria | Diving Megale Hellas

The Deep dive Air course gives skills to practice dives breathing air within a maximum depth of 50 m or 60 m, with decompression stops with Nitrox 50.

www.megalehellas.net

They were so busy figuring out if they could, they never asked themselves if they should...

 

[lostsheep]

I think people are bringing the race car to the grocery shop.

60m on air is like bringing a clown car to Mondello Park.

 

[ginti]

I haven’t heard of a single case of someone dying at 60m or less because of narcosis.

Has Rebreather Diving Gotten Safer?

The view among many industry insiders, Pre-RF4, was that rebreather diving has gotten safer—an improvement from the estimate that CCR divers were 5-10x more likely to die than their open circuit counterparts, which was put forth at RF3 (2012). Afterall, aren’t most people doing their pre-dive...

indepthmag.com

I wonder whether you can put "narcosis" as a cause of death in an autopsy. I am rather sure doctors just can't, because that is NOT the medical cause of death. In other words, even if the trigger for the events that led to the death was narcosis, you would not see it. Happy to change my mind if some doctors or lawyers are here to discuss how it really works.

I imagine most ccr divers with a decent amount of open circuit tech diving experience would agree that the ccr is not the right choice for every dive. I still think 160 on air at Buford is a poor choice tho

As a very unexperienced CCR diver, I agree with you in general (although there are so many other things that may dictate wether or not using a machine or not in a dive). But the point is another one - diving air at 160ft overhead, is a poor choice. If people understand the risks and they want to do it, fine - but it still remains a poor choice.

Then doing this dive on OC air would be like bringing a beach cruiser bicycle to the 24 hour le mans race...

I don't think anyone would seriously say this would be dangerous and stupid on OC. The problem is air instead of trimix.
And, come on, air to ~50 meters? Why?

Air to 50m - why? Because some time ago people used to do it; now technology, knowledge, etc., have evolved, but those who started like that do not want to adapt - and I am sure they won't. Again, I believe it is mostly fine if they understand the risk(s); not really if they underestimate them though...

 

[CG43]

Do people really get only a "little" narcosis at 160 feet on air or EAN?

Shure , 160 feet is not a great depth for someone who is used to this.
This requires that you can dive much greater depths with OC air under ideal conditions (low physical and mental demands). You have to be fit, have a relaxed diving style where you produce little CO2 , breathe calmly and deeply to flush your lungs well.
As a fun diver you look for exactly such conditions or deny the great depths.

How does "proper training and experience' negate physics?

You're right it can't, but you're working with the wrong values.

We old divers did not learn to dive from padi but e.g. from Cousteau's "The silent world".
And of course we have also exerienced this ourselves, at least quite a few of us and what we have found is that these values are correct.
For me solo and with two good buddies, 80 m (262 feet) became the standard depth under good conditions in the red sea. The greatest depth I dived was 93 m (305 feet) .
This was the greatest depth that F. Dumas of Cousteau's team has dived and I have always felt respect and gratitude for these divers who have dedicated their lives to finding boundaries.
My resolution was therefore always : I will dive no meter less and no meter more.
As I write this, I'm drinking a glass of red wine to the good J.Y. Cousteau/F.Dumas and especially to Maurice Fargues, who lost his life trying to dive 120 m (394 feet) with air.

 

[hroark2112]

I recall one. Instructor shut down a student that they had not properly trained to handle a shut down. Forgot why the instructor couldn't get back to the student to correct his mistake before it was too late.

IIRC that incident was in a cave CCR course and the instructor had a cover over the students mask, making it so they could not monitor their PO2. A standards and training violation at minimum. Suicidal at worst.

 

[Brett Hatch]

Shure , 160 feet is not a great depth for someone who is used to this.
This requires that you can dive much greater depths with OC air under ideal conditions (low physical and mental demands). You have to be fit, have a relaxed diving style where you produce little CO2 , breathe calmly and deeply to flush your lungs well.
As a fun diver you look for exactly such conditions or deny the great depths.


You're right it can't, but you're working with the wrong values.

We old divers did not learn to dive from padi but e.g. from Cousteau's "The silent world".
And of course we have also exerienced this ourselves, at least quite a few of us and what we have found is that these values are correct.
For me solo and with two good buddies, 80 m (262 feet) became the standard depth under good conditions in the red sea. The greatest depth I dived was 93 m (305 feet) .
This was the greatest depth that F. Dumas of Cousteau's team has dived and I have always felt respect and gratitude for these divers who have dedicated their lives to finding boundaries.
My resolution was therefore always : I will dive no meter less and no meter more.
As I write this, I'm drinking a glass of red wine to the good J.Y. Cousteau/F.Dumas and especially to Maurice Fargues, who lost his life trying to dive 120 m (394 feet) with air.

Today I will have a beer in honor of the late, great Vesna Volutić, the Serbian flight attendant. Vesna is well known the world around for surviving a fall with no parachute from a height of 10,160 meters (over 33000 feet) in the year 1977. Personally, I would not attempt a fall from even 1 meter more than she did.

 

[broncobowsher]

Shure , 160 feet is not a great depth for someone who is used to this.
This requires that you can dive much greater depths with OC air under ideal conditions (low physical and mental demands). You have to be fit, have a relaxed diving style where you produce little CO2 , breathe calmly and deeply to flush your lungs well.
As a fun diver you look for exactly such conditions or deny the great depths.


You're right it can't, but you're working with the wrong values.

We old divers did not learn to dive from padi but e.g. from Cousteau's "The silent world".
And of course we have also exerienced this ourselves, at least quite a few of us and what we have found is that these values are correct.
For me solo and with two good buddies, 80 m (262 feet) became the standard depth under good conditions in the red sea. The greatest depth I dived was 93 m (305 feet) .
This was the greatest depth that F. Dumas of Cousteau's team has dived and I have always felt respect and gratitude for these divers who have dedicated their lives to finding boundaries.
My resolution was therefore always : I will dive no meter less and no meter more.
As I write this, I'm drinking a glass of red wine to the good J.Y. Cousteau/F.Dumas and especially to Maurice Fargues, who lost his life trying to dive 120 m (394 feet) with air.

A co-worker was telling me about a college buddy who drank a lot. So much so that they could pass a sobriety checkpoint, but would blow triple the legal limit. Is that the same "often enough" you describe?

You think you are doing fine. You can try to convince others that you are fine. Someone with some Helium in the mix will be looking at you going, he isn't fine.

 

[justinthedeeps]

Ok then, so just do that 50m/160ft bounce dive on a tank or two of open circuit air and call it a day. That's the answer for anyone with a doubt.

'Keep it simple.' Even a 60m/200ft dive can easily be done on a simple single S80 of air (I've done it, many have)

The dive won't be as good, mind will be compromised, and fewer safety features will be carried, but at least it will be simpler and cheap[er]

There are after all far more human and equipment errors possible with rebreathers, even though they objectively also provide greater safety margins when used properly.

But [from below] it seems like the CCR stats are improving, with better training and design approaches expanding to a greater share of less reckless divers.

Fock at the time estimated that the risk of dying on a rebreather was five to 10 times the risk of open-circuit scuba. (Fock AW Analysis of recreational closed-circuit rebreather deaths. 1998–2010. Diving Hyperb Med 2013;43(2):78-85).

(below)

 

[OTF]

Rather than continue to rehash the deep air debate - at what depth does CCR become safer than OC Trimix?