Filmmaker Rob Stewart dies off Alligator Reef

[St John the Diver]

If that's the case, why would anyone dive the rEvo w/ hypoxic dil? Is there not a better option?

Yes.

Another rebreather.

The flaws are as follows:

1: Overly sensitive due to its grossly oversized diaphragm.

2: downstream valve (creeping intermediate pressure in a dust stage free flows it rather than locking it shut)

3: unable to be isolated.


It's a bad design to start with and a terrible one for use with hypoxic diluent.

 

[St John the Diver]

You're not waving "I am OK" if you are panting like a dog from hypercapnia, from what I heard others report.
This being said, I would not trust the rMS with my life, from my personal experience with its potential unreliability (cold water, shallower, shorter dives).
But at 2 hr (tops?) per dive during the first 2 dives, in warmish water, unless they had to raise the wreck to free the anchor, I would venture to say that they had plenty of autonomy with proper scrubbers.
Now, there is no way to know whether that was the case, since the rMS reading are not recorded (just a brief cryptic and mostly useless summary post dive, in the best cases).

A simple multideco calculation, 10/50 diluent, using my 30/80 GF settings gives this for 2 dives with 30 min bottom time (22 min at depth) separated by a 3hr SI:

dive 1: RT = 117 min
dive 2: RT = 128 min (CNS toxicity alert)

After 1 hr of trying to get the anchor off the wreck, they go down for a 15 min BT (7 min at depth)
dive 3: RT = 38 min (CNS toxicity alert)

That's not 5 hrs on the scrubber, which is within specs (here). I would not consider hypercapnia of BOTH divers too plausible.

With a 1 l/min O2 metabolism (high), they would have used up very little of their 400 l of O2 at the bottom (assuming a full tank at the beginning), but 230 ft is 8 ata, so just filling the counter lungs (4.5 l non CE for the micro) would be at least 36 l right there. 117+128+38+3x36 = 353 l...

Now, without the computer readings, this is all pure speculative scenario.

Hearing bragging about getting 10 hours on the scrubbers while stupidly relying on the RMS: What did they do the day before?

 

[uwxplorer]

Hearing bragging about getting 10 hours on the scrubbers while stupidly relying on the RMS: What did they do the day before?

There is no way to know because the rMS "log" only shows the last 2 dives "summary".
Shearwater could help with the previous dives though, as they keep RCT and RST of all dives in their internal log (even though they are not shown on their desktop software) - but not the corresponding depth and temperature, so it's only a partial information (assuming you treat this as info in the first place).
But if what you are suggesting is correct, their RCT should look something like 9:00, 7:00 (day 1), 5:00, 3:00, 1:00 (day 2, the day of the fatality). The problem is that the last 1:00 would need to be taken with a grain of salt (or lots of sea water).

 

[Greenjuice]

Possible silly question from a non-CCR diver:
Is there any aspect of CCR training which would allow a student to (safely) experience mild hypoxia or hypercarbia?
[like for example, experiencing being narc'd on deep dive training in AOW?]

 

[RainPilot]

Possible silly question from a non-CCR diver:
Is there any aspect of CCR training which would allow a student to (safely) experience mild hypoxia or hypercarbia?
[like for example, experiencing being narc'd on deep dive training in AOW?]

Not as part of CCR training per se, but there are facilities for high altitude chambers which can do the job. Many flight medical institutions have these.
Of course, you could just get a tank of 10/50 and breathe it for a bit and see. Recommend you make sure it's safe to do so first (i.e. dry on a sofa with someone to check on you etc), I did something similar with my CCR when I first got it. I set it up without a canister, lay back on my sofa and breathed it for a few minutes. 5 min like the prebreathe didn't have a huge effect. 2 minutes later and I now know what a CO2 hit feels like.

 

[Effervescent]

If that's the case, why would anyone dive the rEvo w/ hypoxic dil? Is there not a better option?

Many people dive rEvos with hypoxic dil, myself included. The key is to always know your PPO2 and keep doing O2 flushes at the surface and at shallower depths as required.

I'm relatively new to diving with hypoxic dil (only Mod 2 but not Mod 3 yet), so others may have better options but you can either manually turn off hypoxic dil at shallower depths by closing the valve or add an slide isolator between the 1st stage and the ADV.

 

[dmaziuk]

Possible silly question from a non-CCR diver:
Is there any aspect of CCR training which would allow a student to (safely) experience mild hypoxia or hypercarbia?

For hypoxia just get a wrestler friend hold you in a rear neck choke and you shall be enlightened.

(Edit: on 2nd thought it should be "endarkened" as it's literally lights out in seconds. It's close enough to how you'd black out from hypoxia, but not quite what happens before the blackout: e.g. see video posted below. That's the scary part.)

 

[wedivebc]

Possible silly question from a non-CCR diver:
Is there any aspect of CCR training which would allow a student to (safely) experience mild hypoxia or hypercarbia?
[like for example, experiencing being narc'd on deep dive training in AOW?]

NoNoNo!!!
I know of one instructor who was exposing his students to hypoxia during their training and I immediately reported him to the rebreather manufacturer. When fighter pilots do hypoxic training there are certified medical staff on hand. Anyone who trusts their life to a MIG pilot wannabe is an idiot. There is no guarantee a person will self resuscitate after such an event and most rebreather instructors are not properly trained to attend to a hypoxia victim. Not to mention the legal ramifications...

 

[kelemvor]

Hearing bragging about getting 10 hours on the scrubbers while stupidly relying on the RMS: What did they do the day before?

Why? Is that like a "low sac" thing on OC? I looked up the price of sorb, if I was looking at the right stuff. Looks like a container of sofnolime 812 is $140 and should get 16 revo cannisters full from that so like $17.50/dive? Surely the motivation wouldn't be the cost.

Also, did you actually hear the people involved doing the bragging yourself?

 

[PfcAJ]

Possible silly question from a non-CCR diver:
Is there any aspect of CCR training which would allow a student to (safely) experience mild hypoxia or hypercarbia?
[like for example, experiencing being narc'd on deep dive training in AOW?]

Experiencing hypercarbia was a part of my rebreather class.