Filmmaker Rob Stewart dies off Alligator Reef

[RainPilot]

I don't know that it is confirmed that it was 10/50. When I used that gas as an example it was because it is a commonly used hypoxic dil, I don't recall reading any reliable info that stated the gas used as a fact.

Then again that was 53 pages ago and I'm getting older...

All hail the great spaghetti monster.

 

[packrat12]

I know I mentioned it as a common hypoxic mix, not a known fact. 10/50 is just common and easy to mix.

and may his noodly appendage touch you also!

 

[scubadada]

I don't know that it is confirmed that it was 10/50. When I used that gas as an example it was because it is a commonly used hypoxic dil, I don't recall reading any reliable info that stated the gas used as a fact.

Then again that was 53 pages ago and I'm getting older...

All hail the great spaghetti monster.

Perhaps my mistake, I took it as fact, my apology if incorrect

 

[cavepiranha]

10/50, info in many previous posts

Thus the question.
Add Helium...
did offer some different mixes...
and it has been speculated a 10/50...however
7/70...don take off the table
check the difference in dive profile

 

[Ron Lee]

Perhaps my mistake, I took it as fact, my apology if incorrect

Few facts are known. Rob Stewart's death is a fact. That Mr Sotis was diving with him appears to be a fact. The dive site and depth should be known factually. Time and date of the event are known close enough.

Likely factual that at least one other diver was on the surface and may have responded to a possible medical issue with Mr Sotis in the water. Dr Sotis (wife) may have been on the boat. Mr Sotis may have had an issue in the water and/or in the boat.

Not a lot of facts at this point.

Some may want details to determine if there was an equipment issue or if they need to modify their procedures to prevent a similar event. Initially that is where I expected this to go. If they used common equipment and some unanticipated series of events caused this event, surely people would want to know that.

However, even as uninformed about rebreather use as I am, I am leaning towards human failure as a likely cause.

I see this often with general aviation fatalities. There were two guys who took off from an airport years ago and within minutes flew into a thunderstorm type cell and crashed. Both died. I do not have radar data showing that system development and movement but it is likely that they could have departed 30 minutes sooner or later...or the next morning and both would still be alive. Get home-itis or get there-itis or similar pressures can be deadly.

In this event, it appears that the death occurred after the third dive of the day. I have no way to compare two 220 foot dives on a rebreather to my simpler open circuit diving but I gather from multiple people here that three dives to that depth are a higher risk than some would accept.

Assuming that was happened (three dives to 220 feet), at least one person has postulated what happened. I probably should find one and paste it here for reference but rebreather folks have likely see it by now.

What I am wondering is are there three ways to have prevented this death. Obviously one is just not doing the third dive. If it was a higher risk dive than most would try, the previous suggestion to add a buoy to the anchor line or just cut it loose would be a safe option. That assumes that they were going to do something with the anchor as opposed to a dive for another purpose.

The second question I have is whether making equipment changes might have altered the outcome. Would changing out the oxygen tank and/or scrubber have lowered the risk substantially?

Finally, would hanging one or more tanks in the water for use by the divers have lowered the risk. Use air, pure oxygen or whatever is suitable for that depth (20 feet?).

 

[uwxplorer]

Thus the question.
Add Helium...
did offer some different mixes...
and it has been speculated a 10/50...however
7/70...don take off the table
check the difference in dive profile

Using the hypothetical plans I described in a previous post:

GF30/80, SP 1.3
Dive 1 (230 ft, 30 min BT = 22 min at depth): 131 min
SI: 3 hrs
Dive 2 (230 ft, 30 min BT = 22 min at depth): 141 min (CNS O2 toxicity alert)
SI: 1 hr
Dive 3 (230 ft, 15 min BT = 7 min at depth): 72 min (CNS O2 toxicity alert)

we now have 344 min breathing 1.3 ata O2 and 3 ascents to the surface (going to 8 ata to 1 ata) for which the lungs need to be filled with ~4.5 l of almost O2 at the surface.
Again assuming a liberal 1 l/min metabolic O2 consumption (and in any case, the rEvo will leak around 0.7 l/min no matter what): 131 + 141 + 72 + 3*4.5 = 368 l.
Remember, if they used a 2 l tank filled to 200 bar, that's 400 l of O2 tops. Even considering the approximations used (and the fact that these BT are completely hypothetical, while not unrealistic), such a "plan" wouldn't be expected to end too well...

Edit : corrected ascent volume addition

 

[reefrat]

Using the hypothetical plans I described in a previous post:

GF30/80, SP 1.3
Dive 1 (230 ft, 30 min BT = 22 min at depth): 131 min
SI: 3 hrs
Dive 2 (230 ft, 30 min BT = 22 min at depth): 141 min (CNS O2 toxicity alert)
SI: 1 hr
Dive 3 (230 ft, 15 min BT = 7 min at depth): 72 min (CNS O2 toxicity alert)

we now have 344 min breathing 1.3 ata O2 and 3 ascents to the surface (going to 8 ata to 1 ata) for which the lungs need to be filled with ~4.5 l of almost O2 at the surface.
Again assuming a liberal 1 l/min metabolic O2 consumption (and in any case, the rEvo will leak around 0.7 l/min no matter what): 131 + 141 + 72 + 3*36 = 452 l.
Remember, if they used a 2 l tank filled to 200 bar, that's 400 l of O2 tops. Even considering the approximations used (and the fact that these BT are completely hypothetical, while not unrealistic), such a "plan" wouldn't be expected to end too well...

Is anyone able to run these profiles through Add Helium's TruDive Planning software?

 

[The Chairman]

The second question I have is whether making equipment changes might have altered the outcome.

My surmise, from the tech and rebreather divers posting in this thread that I trust: Don't go too far, too fast. Diving is all about limits and experience is one of the most commonly violated limits.

 

[jonathan d iseson]

In my basic CCR course on my O2ptima rule , when you first touch the bottom, you isolate the Dil from the ADV. Run Dil manually that point on. Makes a ton of sense. Use it always

 

[Wookie]

My surmise, from the tech and rebreather divers posting in this thread that I trust: Don't go too far, too fast. Diving is all about limits and experience is one of the most commonly violated limits.

It is interesting and we used to see this on the Spree often. Experienced rebreather divers who don't need their O2 topped up.
Gas Passer: "Let me top your O2 and dil".
Hairy Chested Deep Sea Scuba God: "Nah, I'm fine, see? 1800#"
Gas Passer: "C'mon, man, it doesn't cost anything and only takes 5 minutes"
HCDSSG: "Really, it's all good"
Grumpy Boat Captain: "Strip your damn unit down and get fills!"
HCDSSG: "Mumble mumble grumble ratzen fratzen"

I still don't know why rebreather divers don't want top ups, but I suspect it's because they have a rebreather that they know is working, and they don't want to jinx it. I've seen an awful lot of rebreathers that worked fine on the last dive, and will be fine on the next dive, but this dive? Not so much.