Deep bounce dive in Cozumel leads to missing diver

[Hetland]

So where did this pair screw up? AWAP suggests that an 80 cf tank could be adequate for a bounce dive to 250'. Personally, I adhere to the concept of deep stops even for normal dives on Cozumel. Ascents are slow and typically spent viewing the reef. They are not square profiles. So given a deeper than normal dive, I would want a larger tank. One to allow plenty of deep stops and two for contingency.

From an education viewpoint, I wonder about the risk of nitrogen narcosis and O2 toxicity at that depth. Just for purposes of discussion, my vague recollection of O2 toxicity is that there are time and depth components. If a few minutes at 250' has a very low risk of an O2 hit, we can disregard it for now for simplicity.

Then you have to wonder about a person's risk of debilitating nitrogen narcosis. Like many things, that could vary among people. Looking back at the Scuba Mau event, unverified recollection is that the plan was to 250' or possibly deeper. At least two of the three people on that dive lived in Cozumel so they had the chance to make frequent deep dives. Were they comfortable with the effects of air at that depth that the risk was relatively low or did others factors come into play to make it a lethal dive?

Return to the two visitors who reportedly went to 250'. Did they make frequent dives to that depth and knew how their bodies were affected? Does frequent diving to those depths allow a person to deal with those effects better, recognize onset of narcosis, etc.

Since I do not know the answers to those questions, it seems that the failure of the buddy system may have been the real problem. How can a buddy come up and say that he thought his buddy was already up? On a high risk dive like this, they should have been very close once they got to a depth that made it dangerous. Not having redundant equipment was likely not the problem. The use of 80 cf tanks versus 120 cf might have been an issue if one diver "lost" his air supply and had to use the buddies octo. But we will never know since from the report we have now, the survivor apparently has no idea what happened to the presumed deceased.

If we get factual info that the two had ascended from depth and the survivor decided to go through a swim through and the presumed deceased signaled that he was surfacing...and that is when they were separated, all this conjecture/scenario analysis can be thrown out.

I will note that in two recent fatalities (maybe more), buddy separation appears to be a factor. One was the cruise ship lady who was diving with her husband..possibly Santa Rosa March/April of last year I believe. Another was the woman from Utah diving with her two brothers. In both cases, there should be factual info available but it never seems to see the light of day.

Personally, I am a strong advocate of rescue diver training. Being able to help your buddy, other divers and even yourself might go a long way to reducing diver fatalities.

No, it's not a buddy system failure, it is a common sense failure. Nitrogen at those pressures is basically an anesthesia gas. Carbon dioxide (which will build up in your system because you won't breathe efficiently at those depths through a regulator) is even worse. Would you go skydiving while huffing ether, chloroform, maybe both? Of course not. Your brain simply stops working the deeper you go. It's like someone is pulling RAM from your computer. Something simple like reading your computer or adjusting your strobe takes 100% of your concentration even at shallower depths. You simply cannot divide your attention and manage another human being. Command decisions are difficult, if not impossible. It gets worse the harder you work (or breathe), because even more CO2 builds in your system, meaning that a panic will probably put you to sleep before your air or bottom time runs out.

It is not a buddy failure if both buddies set out to do stupid $#!^ they know is likely to kill them.

 

[Tortuga68]

I remember Ron repeatedly mounting this same argument in the last deep/bounce/death thread; frankly he just doesn't understand what narcosis can do to people

 

[gkwalt]

Oxygen toxicity, nitrogen narcosis, bad luck, no buddy...? It doesn't make a difference. If you do something wreck less and beyond your training while diving...you may end up a statistic. When people find out that I am a diver, more often than not, their first question is, "How deep have you gone?" I dive to experience the beauty and the serenity, not to prove anything.

 

[AfterDark]

Read somwhere, that rare oxtox cases happened between ppO2 1.4 and 1.6bar. 2bars are definitely toxic, the diver maybe has 90% chance to blackout in a couple of minutes.

Somebody should have told the French navy, 2.0 was their limit for years. Cousteau used 2.0 as the limit for their diving also. So 2.0 isn't definitely toxic there were thousands of dives conducted at 2.0 without oxtox, could still be today somewhere in a military or comm. diving.

 

[supergaijin]

Ox-tox is possible on air... but for a deep bounce it is not the defining factor as your bottom time is seconds rather than minutes. A deep bounce requires a buoyant ascent- inflating the BCD to get up to a more manageable depth before controlling the final ascent. Theoretically you don't have a DCS problem. This is based on the Haldane theory of atmospheric pressure ratios.

Most accidents at depth are believed to be due to narcosis.
Equipment failure, not managed efficiently due to narcosis.
Air depletion not managed properly due to narcosis.

Deep Stops are not part of the bounce dive as they are not needed as long as you get down and get up very quickly. As soon as you start making a 'normal' dive ie. looking around at stuff, the Nitrogen loads very quickly and you will incur some lengthy decompression stops. Bounce Dive profiles are fundamentally different from 'normal' dives.

 

[Dyver]

to go deep for the sake of doing it? I've been down there . . . there's nothing different about 170 feet compared with 30, except it's darker and there is less marine life./ I don't understand the allure of depth for its own sake, when you can have just as much fun much more safely when you are closer to the great air tank in the sky.

When I think of diving in Cozumel, I think nature. What a waste of a trip to go bouncing in the dark, unless one is technical diver or has reason to be down there.

---------- Post added June 5th, 2013 at 06:52 PM ----------

When people find out that I am a diver, more often than not, their first question is, "How deep have you gone?" I dive to experience the beauty and the serenity, not to prove anything.

Through some pattern of synchronicity, all the divers in my family think 50' is deep enough. Unless there's a wreck, nothing really brings me into the triple digits. Why complicate a dive plan?

 

[Stoo]

Whenever I read one of these threads dealing with very deep air diving, (and it's unfortunate that this particular one ended in a fatality) I am taken with the large number of "expert opinions" from relatively novice divers, who have often never been below 100' feet for fear of imploding and having their PADI AOW card melt.

I'm entering my 40th year of diving. I routinely dive 170' - 190' in Great Lakes water, on air, and function quite nicely. I do it mostly solo, and run a complex DSLR while I'm there. I don't advocate this for everyone, but there is lots of deep air diving going on out there. I've never had a problem I couldn't resolve, I've never been bent on one of these dives. However, I take them seriously, and I dive conservatively and pay close attention to how I feel. I also readily acknowledge that there is a significant difference between 180' and 250'

When I learned to dive in the '70s, the guys I learned to dive from were frequently diving 200' plus on air, in water that was in the 38F to 42F range. Yes they were wearing doubles, because they were not doing bounces. None of them died. None got bent that I'm aware of. There were many fatalities in these parts in those days, but they tended to be in 60', 80', 100'... They used watches and depth gauges and tables...

My point in all of this is only that it is quite possible to complete a very deep dive on air. People do it all the time. Is it the best way to do it in these days of mix? Of course not...

Was this guy wise in doing it on a single 80? I don't know anything about his consumption, so I won't comment, but it sure didn't give him much of an option when the excrement hit the oscillator. He might have run out of air. He might have blacked out from CO2 accumulation, or he could have toxed out. Or giggled himself to death. Odds are, his reg didn't freeze up though~

Anyway, my only point in saying all of this is simply that it's easy to get all judgmental and "mightier than thou", but the reality is, that this kind of diving goes on, and there are many dives like this every day that are completed successfully.

It's unfortunate that this has occurred but the fatality might help others decide that this diving is NOT for them...

 

[boulderjohn]

When I think of diving in Cozumel, I think nature. What a waste of a trip to go bouncing in the dark, unless one is technical diver or has reason to be down there.

I have not done many deep dives (200-300 feet) in Cozumel, but in my experience, there is not a lot of reason to go there. There may be some black coral at about 200 feet, and there are some more lionfish between 100-200 feet. After 200 feet it is by no means dark, but there is a grayish pall over the wall, with none of the beautiful coral and sponges you see in the shallower depths. Each of the dives I did demanded a lot of decompression time, and I was glad of it, because the best part of the dives was during the ascent in the region between about 110-40 feet.

Anyone doing a bounce dive on a single tank to 250 feet in Cozumel has got to be doing it simply for the very brief thrill of defying the rules and being that deep, perhaps enjoying the sense that they are somewhere on the cutting edge of diving. They are not. It is the action of an amateur.

 

[Johnoly]

.....Anyone doing a bounce dive on a single tank to 250 feet in Cozumel has got to be doing it simply for the very brief thrill of defying the rules....

Nope,,,,They do it for bragging rights to their friends, usually with a photo of their computer depth. Dive within your limits / training / & Equipment.

 

[clownfishsydney]

There is no reason to go to any depth, no matter if it is 18 metres (60 feet) or 60 metres (200 feet) unless there is something there that is worth the risk justification. If a site has reef to 12 metres and then a sand slope with no life to 18 metres, why would you go any deeper than 12 metres? Only to big note yourself in my view.