Filmmaker Rob Stewart dies off Alligator Reef

[Brad_Horn]

Agree completely. IF however he was hypoxic on the loop then he would have removed his DSV ASAP, I can see a scenario where someone would not think of closing it before ripping it out to get a good lungful of atmospheric. I am definitely going to review my diving because I honestly am not sure that I always close the DSV before removing it on the surface. I think I do but now I will make sure.

The BOV was invented as a means to safely allow a diver to rapidly change to a known safe OC gas; it's not exactly a new concept. Patent US5127398 - Breathing apparatus mouthpiece Will be interesting to see if lack of this standard safety item for rebreather use, is identified in the accident analysis. As per the debate on lack of a gag/retaining strap.

If you are worried about the loop flooding when you want to talk on the surface, or swap to another reg when dived, just use a BOV with an integrated auto-shutoff. Patent US20100043797 - Combined rebreather bail out valve and loop volume valve

 

[RichardC]

Just observing that Raymaekers is out of the rebreather business. I'm not even sure you can buy a new rEvo now as Mares takes it on. Their last rebreather entry was a disaster. Perhaps it'll go better this time.

John, I agree with all of your considered points about gag straps.

However, I must correct you on this last point. Paul is definitely not out of the rebreather business and not even out of rEvo. The deal with Mares was conditional on his remaining in charge for some (I think four) years and rEvos are still made in the same factory, which is next to Paul's metal fabrication business. No alteration has yet been made to the unit.

 

[RichardC]

With a deep bounce dive shortly after your second dive couldn't you also get bubbles from the previous dives compressed enough to make it into the arterial side?

AJ mentioned this a few days ago.
Why We Do Not Bounce Dive After Diving in the WKPP | Global Underwater Explorers

Yes absolutely, all that you say! I'm sure a bounce dive can aggravate the situation and encourage bubble migration.

Of course the slow tissues are what matters here as they are where the dissolved gas will reside, the fast tissues having already cleared between dives. The trouble with multiple deep dives close together is that you pump up the slow tissues.

I think that people are doing more deeper dives these days and we are starting to ask questions of the models not previously asked.

The thing about the NEDU study was that it seemed to imply that there were processes going on in the slower tissues that were not understood and that more work was needed. They initially believed that the deeper stop profile would protect the divers by controlling the bubble radius in the leading tissues (like VPM does), but it didn't work out that way because that loaded the slower tissues more, which seemed to matter more than the traditional models would suggest. Again stretching my memory, but I think there was an indication of a statistically higher than expected level of type II DCS in that study.

Only single dives were studied by NEDU, but the message I took away was that we need to be careful about the slower tissues because the traditional limits might be too aggressive, for some people at least. Multiple dives close together are going in the wrong direction for that. Add in a deep bounce as well and....

 

[KDAD]

Actually gag straps are a proven component that save lives (there's a French study demonstrating their efficacy). Which is why Paul Raymakers supplies them as stock on all Revos.

I was being tongue in cheek. In addition to being a safety feature, the gag strap also helps with jaw fatigue. Not using one defeats the safety aspect (and can be suicidal). I can see how it would interfere with a bungee necklace but that means that you do away with the gag strap? Or do you do away with the necklace (or some other solution)?

 

[DanBMW]

I have read most of this thread and first up, I know very little about rebreather and have never used one. My comment concerns hypoxia. I have suffered it's effects skydiving and can state, that in my case, there were no warnings. It might not be the same in reference to a rebreather though. I have had hypoxia training in a high altitude chamber and know the so-called warnings, but in my case, there were no warnings. I was still in the airplane and was told that I dropped like a sack of potatos. There was no warning.

 

[Dan]

I have read most of this thread and first up, I know very little about rebreather and have never used one. My comment concerns hypoxia. I have suffered it's effects skydiving and can state, that in my case, there were no warnings. It might not be the same in reference to a rebreather though. I have had hypoxia training in a high altitude chamber and know the so-called warnings, but in my case, there were no warnings. I was still in the airplane and was told that I dropped like a sack of potatos. There was no warning.

That's why we have a buddy system & good surface support in these kind extreme diving.

As mentioned before, we need to get positively buoyant as soon as we reach the surface in whichever ways possible with nose above water in neutral position (without finning) & expect to pass out at anytime without warning.

 

[Storker]

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[Tricia]

Could very well be that simple.

And probably is.

I'm a "simple recreational diver", but this post reminds me of something I learned here from Dandy Don many years ago: I never take my reg out until I am back on the bench on the boat. Yeah, people look at me funny and no, it's not very "cool". But it's the safest way to get back to the boat.

 

[Christopher_B]

Any new details come to light over the last few days?

 

[The Chairman]

None that I'm aware of.