Rob Stewart and Third Dive

[Kay Dee]

Sotis was not treated in the chamber.
Stewart's rebreather did not flood.
The hose from Stewart's BCD to his rebreather was not connected.

Thanks for all the updates!

Then IMO, if Sotis did not need a chamber ride post dive then it seems very unlikely a Type2 hit for him, but something else. Be that as it may, thats just my opinion, worth diddly in the grand scheme of things.

 

[justinthedeeps]

Here is the data from the surface interval, which I posted earlier. It shows the ppO2 never dropped below 0.60. Stewart made two manual additions of O2 in the first minute, then took the mouthpiece out of his mouth (the data is consistent with witness testimony), closed the loop, and thereafter the rebreather's constant mass flow device continues to add a small amount of O2 periodically for the next two minutes and the ppO2 climbs gradually. While on the surface, Stewart was breathing either a high percentage of oxygen on the CCR or air, never hypoxic diluent.

The dive computer recorded the fourth dive (see attached).

Additional factors include hypotension, fatigue, the impact of rapid ascent, the impact of a prescription medicine whose side effects include fainting and low blood pressure, etc.

Thank you for clarifying, had missed that this was the surface interval afterwards.

I guess this is partly why it can help to have support divers or additional crew along to assist in aggressive diving plans. Someone prepared for this might have been able to maintain airway and buoyancy for the incapacitated victim. But a disconnected BCD would make that tricky.

It is indeed scary and unexpected to consider the possibility that someone could experience a transient 'blackout' from helium embolisms(?) without much warning, and yet also promptly recover, as long as they have not sunk.

Should we should be staying on a gag-strapped loop, even at the surface?

 

[uwxplorer]

The hose from Stewart's BCD to his rebreather was not connected.

No!? Was that also AH SOP? When at the surface, disconnect your BC?

 

[rjack321]

Should we should be staying on a gag-strapped loop, even at the surface?

The surface is definitely a danger zone on any CCR. I dont know why you'd skip a gag strap there. You do have to be mindful of hypoxic gases, but at least if your ADV did accidentally fire and drop your ppO2 or you switched to BOV mode with a hypoxic gas your loop is much more likely to stay in with a strap.

 

[justinthedeeps]

No!? Was that also AH SOP? When at the surface, disconnect your BC?

What were the divers carrying for bailout?

Sometimes on deep dives we connect the BCD wing to a separate small air fill bottle.

Other times, connected via LPI whip to the cheapest bailout gas, e.g. the 50%. That way valuable or limited trimix diluent is spared.

 

[Subfiend]

What were the divers carrying for bailout?

 

[Subfiend]

The surface is definitely a danger zone on any CCR. I dont know why you'd skip a gag strap there. You do have to be mindful of hypoxic gases, but at least if your ADV did accidentally fire and drop your ppO2 or you switched to BOV mode with a hypoxic gas your loop is much more likely to stay in with a strap.

Stewart manually removed the mouthpiece and closed the loop after one minute on the surface. He remained on the surface for another almost two minutes with the mouthpiece out. A gag strap isn't going to help you do anything but keep the loop nearby when it's already out of your mouth.

Another interesting point: The gag strap had been removed, as well as the OEM mouthpiece. The mouthpiece was replaced with a smaller off-brand mouthpiece. The US Navy measured a higher work of breathing at higher breathing rates, likely because of the smaller mouthpiece.

 

[flymolo]

Are those CO values, referenced in the table attached above, inline with what we'd normally expect?

 

[nadwidny]

Are those CO values, referenced in the table attached above, inline with what we'd normally expect?

No. There should be zero CO. Also the CO2 levels are higher than what I would expect to see especially in the 50% bailout. That number should be around 200-250ppm, not almost 600.

 

[justinthedeeps]

CO looks 'fine' (much below 10 ppm). The CO2 in the 50% probably wouldn't be noticeable at deco depths ≤20m ('1800ppm' equivalent at 3x pressure?). Might be common in nitrox membrane systems that concentrate heavier ambient gases (O2, CO2, argon)

Is there any precedent for deep commercial/sat divers to pass out on deck after rapid ascents that skip in-water Buhlmann decompression? I was under the impression they just strip down and walk themselves into a chamber. But maybe you don't here about the others.