Filmmaker Rob Stewart dies off Alligator Reef

[oya]

Contaminated gas is a silly theory. That bites you towards the beginning of the dive, not the end, or certainly as yo start to descend and the partial pressure of the contaminant builds.

Sudden unconsciousness on a CCR sounds like hypoxia. But it is, of course, hard to say what happened without knowing any more details than "he blacked out." Two people at once is certainly bizarre.

Questions that one would want answered before even starting to frame a hypothesis:
What was their dive plan?
What was their dive time?
What was their actual profile?
Does their computer show anything unusual?
What does their computer show the PO2 as?
What rebreathers?
What breathing gasses?
How long had they each been diving that unit?
What was the state of the rebreather?
How long did they have on their scrubbers?
And on and on and on and on.

But please do go on and speculate wildly. It is fun to read.

In the meantime there's nothing wrong with hoping for a miracle, but my deepest condolences to his family, friends, and the boat crew. Godspeed to the searchers.

 

[cerich]

I have read it was the third dive of the day with a planned 70 meters depth. No idea what dives 1&2 were, but that is aggressive.

I would not rule in or rule out massive DCS hits... but still it's too early to speculate and while the window is closing rapidly let's hope he is indeed on the surface floating.

 

[kelemvor]

Contaminated gas is a silly theory. That bites you towards the beginning of the dive, not the end, or certainly as yo start to descend and the partial pressure of the contaminant builds.

Sudden unconsciousness on a CCR sounds like hypoxia. But it is, of course, hard to say what happened without knowing any more details than "he blacked out." Two people at once is certainly bizarre.

Questions that one would want answered before even starting to frame a hypothesis:
What was their dive plan?
What was their dive time?
What was their actual profile?
Does their computer show anything unusual?
What does their computer show the PO2 as?
What rebreathers?
What breathing gasses?
How long had they each been diving that unit?
What was the state of the rebreather?
How long did they have on their scrubbers?
And on and on and on and on.

But please do go on and speculate wildly. It is fun to read.

In the meantime there's nothing wrong with hoping for a miracle, but my deepest condolences to his family, friends, and the boat crew. Godspeed to the searchers.

If this ends up like most dive accidents, those things will never be released. So, ignore the fact that it happened, or speculate based on the limited data. The hypoxia theory certainly sounds plausible. We obviously can't count on the news, who got even the dive site wrong.

Assuming the buddy who was not lost is conscious now, perhaps he will help inform folks.

 

[grf88]

The following is taken from:
scubish.com: Reference - Underwater Physiology - RESPIRATORY PROBLEMS IN DIVING
"While at depth, the greater partial pressure of oxygen in the breathing supply forces more oxygen into solution in the blood plasma. Some of this additional oxygen reaches the cells and helps to offset the hypoxia. In addition, the increased partial pressure of oxygen forcibly displaces some carbon monoxide from the hemoglobin. During ascent, however, as the partial pressure of oxygen diminishes, the full effect of carbon monoxide poisoning is felt."

This would suggest that contaminated gas is not necessarily a "silly theory". I have little knowledge of rebreathers but wonder if coming off the loop reduces the PP of O2.

 

[cerich]

This would suggest that contaminated gas is not necessarily a "silly theory". I have little knowledge of rebreathers but wonder if coming off the loop reduces the PP of O2.

depends on what gas they are breathing after they come off the loop. That all said, depending on what the gas issue is it will take some time (and possibly medical intervention) to resolve/mitigate whatever gas issues the diver was having.

Narcosis is something that can be induced or cleared very quickly with a gas change, oxygen toxicity, CO2 can take some time on the new gas, C) can be a real ongoing issue that can and has required medical intervention.

 

[mderrick]

Interesting to me that the discussion here seems to be focusing on the CCR, when as several people point out there is little commonality to explain two divers going unconscious shortly after reaching the surface on third dive of the day. Yet I've seen this exact circumstance several times in my career when the divers were on open-circuit. The cause in those cases... omitted required decompression.

 

[cerich]

Interesting to me that the discussion here seems to be focusing on the CCR, when as several people point out there is little commonality to explain two divers going unconscious shortly after reaching the surface on third dive of the day. Yet I've seen this exact circumstance several times in my career when the divers were on open-circuit. The cause in those cases... omitted required decompression.

ummm... actually I postulated on exactly that earlier. more interesting to me is how quickly the ccr crowd jump to make sure that ccr's are not considered as possibly contributory to things.

 

[oya]

So, ignore the fact that it happened, or speculate based on the limited data.

As I said, please, by all means... make up lots of uniformed theories. The wilder the better.

Bonus points if you can involve some completely esoteric medical condition that has only been recorded in one other case ever during the building of the Brooklyn Bridge, but otherwise managed to hit two divers at the exact same time.

If I'm going to shoot blindly in the dark myself I'm going to go with accidental drop to hypoxic PO2 during surfacing or a ton of omitted deco. Two things that could happen to two divers struggling to stay together.

 

[DanBMW]

Any word on the other diver's medical condition after surfacing?

 

[Cali_diver]

Here is an interview with Rob's sister: