Anyone know who were the divers who recovered Stewart?
Filmmaker Rob Stewart dies off Alligator Reef
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uwxplorer
Contributor
Sorry to interrupt the ebb and flow of the discussion...
I just wanted to point out that I corrected a mistake in my estimate of the O2 gas consumption during ascent (I probably should not have written that while working on something else at the same time) (*).
The amount of O2 to be injected to preserve a pO2 of ~1 throughout ascent is essentially equal to the counterlung volume at the surface (I take the manufacturer value for the counterlung volume as a ball park value).
This reduces the total amount of estimated O2 consumption by ~95 l, which is obviously a significant gain.
However, in the last scenario, where I used typical AH-recommended settings, the total volume still amounts to 345 l, close to the nominal 400 l of a 200 bar 2 l cylinder.
Again bear in mind that the BT, O2 metabolism, SI, etc. I used are hypothetical but, I would argue, realistic.
I did not factor in these estimates a few other unknowns:
- it is recommended by rEvo to calibrate the unit after each build. I do it at the beginning of a dive day. This uses quite some O2 (triple flush of O2). In my case, I typically lose 10+ bar of a 3 l, 200 bar cylinder, i.e. 30 l or more. I don't know what the AH-recommended practice is.
- it is recommended by many agencies to perform a loop flush at 20 ft, to verify that the cells read 1.6. Some do it on the way up instead of down (less gas needed), some don't. You can lose 10+ l right there.
- moving an anchor at 230 ft (without a bag) requires a lot of energy. Not only does the metabolism go up, but you would go up and down, up and down, venting your loop (and BC) quite a few times in the process. I have done it at shallower depths, and it is a bitch. Using a bag is a much better approach, but if you have minimal bailout gas, this is not necessarily a good thing to do either... Your heart beat doesn't go down immediately, CO2 level goes up, etc.
All this to say that I am not defending any scenario, just pointing (again) that this was for me an illuminating exercise, as I was trying to understand whether two divers could come close to hypoxia at the end of a third dive without any foretelling incident.
Once again, my deep sympathy to relatives and all involved. A great human being was lost, and we are all trying to learn how to avoid a similar tragedy from occurring in the future.
(*) Thanks to RainPilot for editing the first post (thrice!).
I just wanted to point out that I corrected a mistake in my estimate of the O2 gas consumption during ascent (I probably should not have written that while working on something else at the same time) (*).
The amount of O2 to be injected to preserve a pO2 of ~1 throughout ascent is essentially equal to the counterlung volume at the surface (I take the manufacturer value for the counterlung volume as a ball park value).
This reduces the total amount of estimated O2 consumption by ~95 l, which is obviously a significant gain.
However, in the last scenario, where I used typical AH-recommended settings, the total volume still amounts to 345 l, close to the nominal 400 l of a 200 bar 2 l cylinder.
Again bear in mind that the BT, O2 metabolism, SI, etc. I used are hypothetical but, I would argue, realistic.
I did not factor in these estimates a few other unknowns:
- it is recommended by rEvo to calibrate the unit after each build. I do it at the beginning of a dive day. This uses quite some O2 (triple flush of O2). In my case, I typically lose 10+ bar of a 3 l, 200 bar cylinder, i.e. 30 l or more. I don't know what the AH-recommended practice is.
- it is recommended by many agencies to perform a loop flush at 20 ft, to verify that the cells read 1.6. Some do it on the way up instead of down (less gas needed), some don't. You can lose 10+ l right there.
- moving an anchor at 230 ft (without a bag) requires a lot of energy. Not only does the metabolism go up, but you would go up and down, up and down, venting your loop (and BC) quite a few times in the process. I have done it at shallower depths, and it is a bitch. Using a bag is a much better approach, but if you have minimal bailout gas, this is not necessarily a good thing to do either... Your heart beat doesn't go down immediately, CO2 level goes up, etc.
All this to say that I am not defending any scenario, just pointing (again) that this was for me an illuminating exercise, as I was trying to understand whether two divers could come close to hypoxia at the end of a third dive without any foretelling incident.
Once again, my deep sympathy to relatives and all involved. A great human being was lost, and we are all trying to learn how to avoid a similar tragedy from occurring in the future.
(*) Thanks to RainPilot for editing the first post (thrice!).
and at that it's seems there is a plot twist. There were media reports it was the Key Largo Fire and Rescue team..except I have heard it wasn't.
I have heard that it was a dive op with a ROV that found it, then recorded the actual divers doing the recovery, even stranger is that one of the recovery divers is the lawyer that is going to defend the boat in the event of a lawsuit. How somebody that should be a witness could defend the boat is beyond me.
What difference would that make in the scenarios being discussed?
If you don't think clearly enough to inflate your wing, would you think clearly enough to inflate your drysuit? Or are you implying that you would have a separate inflation system for the drysuit, so if you ran out of dil for inflating your wing, you would still be able to inflate your drysuit? In that case, aren't you just trading one potential problem for another (that you could find yourself out of suit inflation gas)?
Don't get me wrong. I'm totally onboard with diving dry for just about any technical diving, really. But, I am unclear on how you think any of the possible CCR problems being discussed would be mitigated by diving dry versus wet.
I did see Leon's video and it didn't impress me much. Just marketing like all rebreather manufacturers do.
There is no dispute that, in the case of this incident, if someone were to become incapacitated then the loop would empty at some rate depending whether the gag strap was used or not, and I think you are assuming it was not.
If used properly the gag strap will keep the DSV in your mouth and seal surprisingly well around the lips so your swimming pool test shouldn't really happen in the way you conducted it, probably taking a great deal longer. If you don't use the strap then it's a bit like leaving your seat belt off and blaming the car manufacturer for a face full of glass.
However, in any event, if you are relying on the lungs for buoyancy then you are at risk, whatever unit you dive, if your buoyancy state is marginal then 30% loss on the lungs will take you down. People have sunk with OTS units in the past so they are not infallible and even a buoyant diver may die on the surface if they end up face in the water.
In general I get fed up with unit bashing without recognising that all rebreathers involve choices. I personally don't like OTS counterlungs and I have valid reasons for my choices. I feel you imply that the choices made on the rEvo are, by design, sub-optimal. On the other hand I think that there are features that make it the safest and probably most extensively tested unit on the market, but like all units it has to be used properly.
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I was not aware that Key Largo Fire and Rescue had a deep water mixed gas dive rescue team. Few departments around the country have that capability. Usually it is done either by a commercial dive operation, one of the fed agencies like FBI, Navy or NOAA, or an all volunteer team of qualified persons. If KLFDR has that kind of capability hats off to them.
In regards to the suspicion that the recovery diver is the defense attorney, there are only a few active attorneys in the dive industry who are certified for that kind of dive. I can only suspect it's Craig Jenni. He's a good diver, we had him out on an Andrea Doria trip back in the mid 1990s when he was heading up the YMCA scuba program. But for the life of me I would not expect a potential defense attorney to handle evidence (yes while that may be hard to swallow, Mr. Stewart is evidence). Most fatalities are considered homicides until accident report is concluded. I would seriously doubt Craig would handle ex parte evidence.
Still interested in the whole recovery scenario from an academic standpoint.
Cheers
JDS
St John the Diver
Contributor
It's all irrelevant to the case at hand.
1: It's established that he was on a rEvo.
2: It's fairly well assumed based on history and publicity photos that there wasn't a gag strap installed.
3: It's an engineering fact that due to choices made in the design of the rEvo that it has the architecture that is most vulnerable to rapid and complete loss of loop gas in an open DSV on the surface scenario.
None of that is really subject to debate. And it's extremely germane to this accident. An inexperienced diver looking at a bad situation I unfolding before him might very well yank out the DSV to shout or ?? and lose buoyancy and be lost. It's an extremely likely scenario in this case, with this equipment.
What you and I choose, for whatever reasons we do, has zero bearing on the above facts. What's important is to realize that "all rebreathers suck" and then to work around the problems that we choose to accept. Knowledge is power. If you dive a rEvo it's good to know about how it needs to be managed.
Cowfish Aesthetic
Contributor
According to this article, published today, Rob Bleser was driving the ROV from onboard the Pisces and two divers who wish to remain anonymous recovered the body.
How they located diver Stewart
The article has the most detail on the recovery that I've seen so far.
So the unit was non standard if no strap was installed. That is important. It implies error on the part of the instructor not emphasising its importance.
The shouting out scenario is only a problem if the diver was not adequately buoyant by other means, as we have discussed. Now what I understand is that the diver, whilst relatively new to rEvos, was far from an inexperienced diver and indeed had experience semi-closed. If he were aware enough to shout out, I imagine he would also be capable of finning up and inflating his wing further if he found himself going down. No - to me it sounds like there was some degree of incapacitation, in which case the gag strap might really have helped.
On this last point we can agree completely.
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