Atticus:The rumor mill suggests that several WKPP support divers were bent doing equipment retrieval bounce dives (source: GI's web page).
Heard the same rumor...
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Atticus:The rumor mill suggests that several WKPP support divers were bent doing equipment retrieval bounce dives (source: GI's web page).
The difference between in-water recompression and going back down and doing omitted decompression is whether or not you have symptoms of DCS.Vayu:Because in water re-decompression can be dangerous.
This looks like a couple of pretty simple yet effective procedures. Too bad these sort of procedure aren't as clearly taught by other agencies.Vjongene:The official CMAS procedure is that once you have regained control of your ascent you stay at current depth for the length of time it would have taken you to get there with a normal ascent (10 m/min). Then you proceed to your safety stop (assuming that you are within NDL).
However, if you reach the surface after an uncontrolled ascent (a more common problem), the procedure is to go back down to half of you maximum depth, spend five minutes at that depth, and then proceed to the surface and do your deco stops (if any) as if you had spent the entire time necessary for the procedure at your maximum
whether or not you have symptoms of DCS.
*Floater*:Very interesting topic. I'll make sure to ask an instructor about this, but my current instinct would have been to re-descend to the missed stop depth or further down (gas supply and other factors permitting of course) in order to compress the bubbles that had formed and potentially gotten lodged in tissues, and then ascend very slowly and carefully in order to give my body time to off-gas them properly.
I had thought the problem with the bounce diving was the quick second ascent - you bubble at the surface and those bubbles are growing, then you go down again so they compress and slip into your brain, spine, etc. but then you bounce up so fast that they don't have time to come out and instead expand in those tissues wrecking havoc. If you just went back down far enough to compress them, and then came up slowly enough to give your body time to off-gas them, then you should be fine.
But this is only based on my very limited understanding of the subject. I'll make sure to discuss it further with knowledgeable people.
jagfish:I heard an answer to this in some recent training...
If bubbles had been formed on your rapid ascent, they would be confined to the "pulmonary" side of your heart and will hopefully be released through the alveoli in the lungs, allowing the diver to remain asymptomatic.
If one descends again, the bubbles will reduce in size, and may be able to pass by the lungs and into the side of the heart that pumps to the brain. At this time, the diver would have micro bubbles in the total circulation system, including neural tissue.
If the diver now ascends before these micro bubbles are completely purged from the blood, one or more of them could expand in neural tissue upon final final ascent.
For this reason, I was advised to never re-descend in this kind of situation.
This is also apparently the mechanism of danger in bounce dives.