Blackout. Currents. Rebreather

[northernone]

Thank you for your thoughts.

1. Absolutely and heartily agree!
2. That's certainly viable, at the time I was concerned with making it to shore, to avoid being a bobbing beacon floating to Cuba, but clearing the deco ceiling felt good. Avoiding the struggle and task load by waiting it out with adequate gas (see point 1) would have been ideal.

3. I only had straight air (reg no lp inflator) and the o2 rebreather (hardplumbed no connections) as bailouts.

I'm considering 4/5 and like the overlooked possibility. Thank you. I did metabolize a lot of o2, hence my shortage, stands to math and reason that my scrubber is absorbing the co2 plus all the scr time, perhaps I need to rethink my hypoxic theory on my blackout. The breath holding while swapping breathers (both to the failed breather and back again on the loop) plus coughing certainly elevated my co2 levels, perhaps I did breakthrough or at least overwhelmed the scrubber. I was using sodasorb 4/8 in a prism topaz (radial 6lb scrubber). I didn't feel the need to hyperventilate like breathing a bypassed or exhausted scrubber, perhaps it was only partial but enough to explain my euphoria.

Thank you again,
Cameron

P.s. Friendly critique is welcome while I do appreciate the non critical attitudes. It's showing me the value of talking about our mistakes/troubles/mishaps.

 

[RyanT]

Cameron, first, let me thank you for sharing. I really believe these kinds of discussions regarding near misses are always valuable. It certainly sounds like a CO2 hit. Hypoxia typically tends to generate symptoms like tunnel vision, confusion, and elevated heart rate and respiration rate. CO2 is a strong anesthetic and is more likely to generate feelings of euphoria that you described. Of course the symptoms are not mutually exclusive, but what you describe definitely sound more like a CO2 issue. Related to this, we had a CCR diver on the boat with us recently in Pompano Beach. The DM came up and said the current was screaming about as fast as he's ever seen. The CCR guy scrubbed the dive and said it wasn't worth risking a CO2 hit from working too hard. Really glad this ended well for you!

 

[abnfrog]

4 8 is not what you should use ....your instructor should have told you that

 

[NYCNaiad]

I'm not a CC diver so can't comment on what happened, but I know how difficult it can be to bare your soul while describing what you see as a failure. I think near miss discussions are incredibly valuable & many divers are too scared to open themselves up to potential criticism so thank you.

 

[northernone]

4 8 is not what you should use ....your instructor should have told you that

In training we used 8-12, but as per the manufactures recommendations: "4-8 mesh absorbent may be used for training purposes or shallower than 140ft, for a maximum of 3hrs in cold water and moderate workload." This was what my instructor taught. With warm water, I planned on 10ft deeper based on the NEDU testing. My decisions post training are my own and don't reflect on my instructor

Where I am surprised is the issues were encountered and developed in 35ft of water with the majority of the dive in less than 100ft.

A little more info:
I examined the scrubber post dive, it appeared well packed (if I do say so myself) and there was perhaps 30% clumping. Just ran the math and theoretically (based on o2 and dill used and assuming no waste with a respiratory quotient between .6 and 1.2) I produced between 90-180L of co2. As per the test data before breakthrough, it should be good for 360L at 2l per minute in cold water. Which is surprisingly consistent with the observed clumping.

Perhaps insufficient dwell time with the reduced surface area of larger granules after the breath holding, even with the o2 flush?

Thank you all for the ongoing discussion. I hope this is my decade's contribution to this section of the forum.

Regards,
Cameron

Ps. Dive profile uploaded for the interested.

 

[northernone]

Cameron, first, let me thank you for sharing. I really believe these kinds of discussions regarding near misses are always valuable. It certainly sounds like a CO2 hit. Hypoxia typically tends to generate symptoms like tunnel vision, confusion, and elevated heart rate and respiration rate. CO2 is a strong anesthetic and is more likely to generate feelings of euphoria that you described. Of course the symptoms are not mutually exclusive, but what you describe definitely sound more like a CO2 issue. Related to this, we had a CCR diver on the boat with us recently in Pompano Beach. The DM came up and said the current was screaming about as fast as he's ever seen. The CCR guy scrubbed the dive and said it wasn't worth risking a CO2 hit from working too hard. Really glad this ended well for you!

Thinking about it,, certainly does seem to fit. Not sure about the memory gap between prone and standing though...very curious my unconscious default is standing, subconsciously proud it wasn't on my knees. (Humor aside. I didn't have the loop volume right after I went OC.)

And yes, it is certainly a difficult thread to post and put my name afterwards. A more enjoyable incident which happening some time ago was when my mouthpiece ziptie broke (no second reg) mid dive. I was the photographer in the group, I informed them of the problem and continued the dive. If I turned my head the mouthpiece left me sucking water while the liberated reg made it's getaway to the depths before dangling like a disappointed chained dog. Turns out I turn my head frequently, particularly when positioning strobes and framing people in a brisk current. A spare ziptie makes for a good dive buddy.

Regards,
Cameron

 

[RyanT]

Yes, and I'm very proud to know someone (even if virtually) who didn't go to their knees under the worst of conditions!!!! In all seriousness, I'm super glad this ended well for you.

Interesting story about the zip tie. I spend a lot of time thinking about redundancy underwater, a zip tie is something that never occurred to me!

 

[TechDeep]

....my mouthpiece ziptie broke ......

In 25 years of diving, that has only happened to me one time. During a drill where I was being scored by an instructor during my IDC. I mean come on, really, in all these years it happens now?!

I was the mock instructor for this drill while the other instructor candidates were rigging a lift bag. They were so focused on what they were doing, they didn't even notice what I had going on. That was fine with me, you never want the student to rescue the instructor while he is being graded! I would imagine the instructor saw it, but he never mentioned it. I got a good score for the drill, so I kept my mouth shut and moved on.

 

[sunnyboy]

My only comment to the OP is that once the bailout RB flooded, given the challenges in returning to shore, it should not have been touched again. Trying to use, then recover the loop on that RB probably didn't help with everything else that was going on.

 

[The Chairman]

I want you to think about this discussion and in a day or three tell us your three biggest take aways from this. I want to see if they stay the same.