Filmmaker Rob Stewart dies off Alligator Reef

[cerich]

A rebreather diver would be carrying 2 bailout bottles (at least). One for deeper the other shallower depths. So I don't understand why some here keep harping about breathing 10/50 during deco. Ascending from depth the diver would be using no dil. O2 would be added to maintain the set point.
At the point the diver runs out of O2 they would then switch to their bailout for the remainder of deco, gas supply permitting. There is also the option of plugging in there shallow gas to the rebreather via the MAV

Al

Looks like uwxplorer and I are thinking the same thing around the same time

would..or should. I see lots of ccr divers at sub 300 with a single 40 "bailout"

Plus, they were filming..

 

[kelemvor]

would..or should. I see lots of ccr divers at sub 300 with a single 40 "bailout"

Plus, they were filming..

Were they? I had missed that tidbit. Wow what a task load he must have been managing for a relatively new RB diver. Also brand new to trimix depths and filming? It must not have been a very fun dive to do, I wouldn't think.

Edit: Obviously he's not new to filming.. I could have worded that better.

 

[dmaziuk]

umm..not quite. If you have have been breathing 10/50 at say 20 fsw, you are gonna go unconscious when you come up, come up slowly and it will occur uw,come up fast and you will on the surface on the surface. Your respiration of the atmospheric oxygen still will take some time to get into the circ system and to your brain box. During your assent the PPO@ dropped and your body was still metabolizing.

if you had been breathing a slightly hypoxic mix on the surface at depth, say a 15, you would most likely stay conscious but have a "gotta stop and breath moment", a 10 and you are gonna most likely enjoy a blackout of a few seconds to say 30 seconds.

Freedivers can go SWBO without breathing a hypoxic mix, or any mix for that matter. If you're not positively buoyant face up in the water, "few seconds" is quite enough to drown, and that's why they typically have a safety diver in the water watching them come up. (Of course that's 20/20 hindsight speaking...)

 

[wedivebc]

would..or should. I see lots of ccr divers at sub 300 with a single 40 "bailout"

Plus, they were filming..

It sounds to me like a bunch of you are grasping at straws to make someone look bad. None of what you are saying has any basis in fact and the imagined scenario is too far fetched to be believed. I was hoping this thread was going to shed some light on this tragic death not be a bash fest.
Peace out...

 

[PfcAJ]

And why would 2 guys with hypoxic loops not switch to bailout at the surface. All these scenarios you guys are conjuring are dealt with in CCR 101 and a trained RB diver would not have these issues you are postulating.

Not paying attention, focused on making progress toward the boat. Everything 'feels' normal.

Hypoxia is insidious.

 

[cerich]

It sounds to me like a bunch of you are grasping at straws to make someone look bad. None of what you are saying has any basis in fact and the imagined scenario is too far fetched to be believed. I was hoping this thread was going to shed some light on this tragic death not be a bash fest.
Peace out...

actually, in the absence of enough facts, there has been postulation of many "possibilities" floated and discussed. You seem to feel that they are all to smear someone, yet in fact when you look over all the "possible" events that lead up to the tragedy there has been plenty of differing views.

 

[St John the Diver]

And why would 2 guys with hypoxic loops not switch to bailout at the surface. All these scenarios you guys are conjuring are dealt with in CCR 101 and a trained RB diver would not have these issues you are postulating.

You're making assumptions of competence that aren't borne out by local personal observations.

 

[RainPilot]

You keep banging on about his hypoxia scenario but can you please explain how 2 rebreather divers find themselves with no O2 and no bailout and nothing to breathe except 10/50 dil. This seems like a very far fetched scenario.
Remember that a rebreather diver has as much as 1.3ata in the loop which if you popped to the surface from 70m you would still have 0.16 atm O2 and hypoxia would be the least of your worries.. I just don't see what chain of events could lead to hypoxia without a whole laundry list of screw ups which I doubt given Peter's experience is likely.

Starting from the top: not banging on, expanding my thoughts on some of the theories posted here.
As @cerich and others have stated, two big dives to 230' and another bounce would suck O2 really fast, trying to keep that 1.3 that you refer to. BTW your calculations for 0.16 on the surface (a marginally hypoxic gas already) is correct IF THEY STOP BREATHING WHILE COMING UP.

No bailout: Rob was on the loop when he surfaced by all accounts as was Peter. If there was a significant issue (significant enough to make both of them pass out within seconds of surfacing) it is likely they would have been on bailout if they had an appropriate gas. I can easily see this conversation playing out:
"Drop down to get the anchor?"
"Sure, how's the gas?"
"Should be fine, it's just a quick bounce."
"Ok Instructor who presents lectures and workshops on rebreather operation "
"Bailout? Yeah just grab the big bottle in case, we don't need all the stages etc"
"Are you sure?"
"It will be fine rebreather diver with 6 months or less experience "

I know and know of many very experienced people that have died from stupid. Nobody is immune and CCR magnifies the consequences.

My reason for leaning toward hypoxia? Of the 3 Hs it's the most likely IMO. Hyperoxia would have at least one of them convulsing and unlikely to affect both in the same way (simultaneous RB failures? On a rEvo? Unlikely. )
Hypercapnia? Sorry Pete but again, it is more likely than hyperoxia but would require them to both kill their scrubbers at the same time and would, while incapacitating them would IMO be unlikely to result in Rob showing OK.

Running out of O2 on an OW dive on a RB is a very uncommon event, but then again nobody seems to be making a habit of doing 3 hypoxic dives in a row on the same unit on the same day.

 

[The Chairman]

You guys are chasing hypoxia and while I first thought that this might be the case, I now believe that hypercapnia is more likely. How DO THEY BOTH run out of O2? Someone mentioned earlier that he thought that they did not change scrubber media. We haven't been given any evidence to the contrary. Given run times of 90-120 minutes, that's a lot of time on that scrubber over 3 dives and they were humping an anchor to boot? That's a lot of CO2. Hypercapnia is not a switch like hypoxia either. The symptoms can be easily overlooked as one of the main ones is confusion. In addition, we have info that something happened to Sotis, but Sotis posted on FB that he didn't pass out. Maybe he was suffering from hypercapnic stupor? He's kind of there, but nobody's home. That might possibly entail stumbling and being unresponsive giving the impression of passing out. If Sotis' scrubber is spent, then in all likelihood so is the Stewart's and he would also be suffering at least some symptoms of hypercapnia. In that state of confusion, all it would take is for the deceased to forget to close the loop when he went off loop and the resultant negative buoyancy would have pulled him under with little hope of recovery. He didn't have to pass out on the surface and might not have shown any obvious signs of confusion. One second he's on the surface and the next one he's headed towards the bottom and he doesn't have his normally sharp mind to help him cope with the situation. Remember, this is all speculation at this point. If this is the case, I bet we find the cylinders empty as he tried to resolve the situation. Nothing the crew could have done to recover him either. Sad, but it fits all the facts we have at present. The ocean is a harsh mistress.

 

[RainPilot]

My mate has a rEvo micro and it claims to have a scrubber duration of 4-6 hours. A 2L O2 bottle lasts how long?

Aforementioned friend averages two tanks to one scrubber on the dives we do together. Also, as O2 consumption is fairly consistent across individuals (to the best of my knowledge) I can see how two divers would run out within a few minutes of each other.

Not ruling out CO2 but my money is on the low PPO2 side.