Thoughts on Bounce Dives
- Thread starter Quinn Ross
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For an air diver, narcosis hits first....for many at no deeper than 130, they begin to lose mental abilities critical to keep them safe with the choices and awareness they will have as they drop deeper.
Even among deep air divers in the 90's ( before any of us had the access to trimix diving) , reaching 200 feet deep meant a serious party buzz, and the effective loss of mental abilities was an immediate danger during each successive minute until they were back to deco stops....A great deal of these dives in S Fl , were to 280 foot deep wrecks and reefs....for durations up to 25 minutes long. Ox Tox was not typically problematic on these, unless someone was fighting with a speared fish at this depth...and then CO2 levels would drastically increase the effects of O2 toxicity...
Many deep air divers had no issue with 25 to 30 minute long dives to 280 or 300 feet deep.... but even more amazing, in one of the tech diving deaths of the nineties, the Jane Orenstein death ( "Murder on the IANTD Express" thread on rec. scuba)... an Instructor, Derek McNulty, failed to watch his buddy and student, Jane Orenstein on one of her first deep training dives from 280 ( on the Rb Johnson/Coryn Chriss site)....and when she did her gas switch from trimix back gas, to travel mix ( nonsense to have travel mix on this also), she was NOT observed reaching the reg for her Oxygen bottle, which she ended up breathing from 100 feet deep, to the 30 foot stop...from which she Toxed on her way from 30 foot stop to 20 foot stop. The time to get from 100 feet, to the 30 foot stop was a huge amount of time breathing oxygen at an equivalent air depth much deeper than 218 feet. In other words, O2 Toxicity can take a very long time to kill you, even at levels far beyond 200 or even 400 feet deep. So the 218 foot depth number is a relatively benign threat, compared to all the immediate and serious threats the deep air diver has to contend with....Make this diver a bounce diver, with skill sets more like a child in a swimming pool ( typical bounce diver trying for a personal best), and Narcosis will be the biggest threat, causing their already seriously defective dive behaviors and problem solving, to get far worse....
As to the "Murder" part of the rec. scuba thread, this Derek guy, just watched her begin to fall, and then drop into the distance...saying later that he did not have enough gas to go after her...
When I did the body recovery the next day with George Irvine, I used less than half of the gas Derek had in his doubles, after he got back on the boat....and that was with me trying to pull Jane and all gear, completely flooded drysuit and tanks, off the bottom and all the way to the surface....alot more weight than my BC and George's could lift.
Even among deep air divers in the 90's ( before any of us had the access to trimix diving) , reaching 200 feet deep meant a serious party buzz, and the effective loss of mental abilities was an immediate danger during each successive minute until they were back to deco stops....A great deal of these dives in S Fl , were to 280 foot deep wrecks and reefs....for durations up to 25 minutes long. Ox Tox was not typically problematic on these, unless someone was fighting with a speared fish at this depth...and then CO2 levels would drastically increase the effects of O2 toxicity...
Many deep air divers had no issue with 25 to 30 minute long dives to 280 or 300 feet deep.... but even more amazing, in one of the tech diving deaths of the nineties, the Jane Orenstein death ( "Murder on the IANTD Express" thread on rec. scuba)... an Instructor, Derek McNulty, failed to watch his buddy and student, Jane Orenstein on one of her first deep training dives from 280 ( on the Rb Johnson/Coryn Chriss site)....and when she did her gas switch from trimix back gas, to travel mix ( nonsense to have travel mix on this also), she was NOT observed reaching the reg for her Oxygen bottle, which she ended up breathing from 100 feet deep, to the 30 foot stop...from which she Toxed on her way from 30 foot stop to 20 foot stop. The time to get from 100 feet, to the 30 foot stop was a huge amount of time breathing oxygen at an equivalent air depth much deeper than 218 feet. In other words, O2 Toxicity can take a very long time to kill you, even at levels far beyond 200 or even 400 feet deep. So the 218 foot depth number is a relatively benign threat, compared to all the immediate and serious threats the deep air diver has to contend with....Make this diver a bounce diver, with skill sets more like a child in a swimming pool ( typical bounce diver trying for a personal best), and Narcosis will be the biggest threat, causing their already seriously defective dive behaviors and problem solving, to get far worse....
As to the "Murder" part of the rec. scuba thread, this Derek guy, just watched her begin to fall, and then drop into the distance...saying later that he did not have enough gas to go after her...
When I did the body recovery the next day with George Irvine, I used less than half of the gas Derek had in his doubles, after he got back on the boat....and that was with me trying to pull Jane and all gear, completely flooded drysuit and tanks, off the bottom and all the way to the surface....alot more weight than my BC and George's could lift.
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Suggest to your friends that are super bendable that they go get a doppler test for a PFO. The current gold standard is the Trans Cranial Doppler, which is non-invasive. It will only tell you if you have one, or not, and not the size of the hole, but it's a good way to find out if that is the issue.
If they test positive, it's fixable. There are some risks involved (they will plug a hole in your heart, what could possibly go wrong with someone monkeying around in your heart?) Those risks need to be weighed by the individual.
FWIW, I used to get bent pretty regularly on 60-80 minute dives in the 90-100' range. I had the PFO closed 13 months ago and haven't had a problem since. My most recent dive was a 180 minute bottom time at an average depth of 140', and a total run-time of just over 6.5 hours. I was the first guy out of the water, and 20 minutes later I was hauling a bunch of heavy gear back to my car. The only problem I had was hunger.
100days-a-year
Contributor
I've told them to get tested.Several have pre existing joint damage from accidents and one got tested and lo had a PFO.
On the other side of the coin are many of my commercial buddies who still dive prehistoric computers all day at 150' to 180' and remain problem free if a few simple rules are followed on SI and RT.
I've seen guys come out of the water like a Polaris missile and continue diving that day,sadly also seen deaths/paralysis result.
On the other side of the coin are many of my commercial buddies who still dive prehistoric computers all day at 150' to 180' and remain problem free if a few simple rules are followed on SI and RT.
I've seen guys come out of the water like a Polaris missile and continue diving that day,sadly also seen deaths/paralysis result.
OP
Quinn Ross
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Thanks for this. Aside from being unnecessarily snarky (we are all just looking for information from those who know more), your post was extremely useful. I should have posited questions as opposed to assumptions. Thank you for the clarification.
I think the moral of the story is don't do it... again
Bob, what 'training' would you consider to be appropriate for such a dive? This is NOT a loaded question, and I do NOT have a hidden / secret answer.
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Personally, I think this is more like the way some guys you know can drink 6 to 10 shots of Tequila, as lightning rounds, and then do a passable job of driving their car home....Others that might drink the same drinks, would need to be carried out of the bar. Point being, those of us that did lots of 200 to 300 foot air dives, were not "gifted" with amazing learned skills...rather, we could "drive on more drinks than most people can"....not really something to be all that proud of....
One reason I am NOT a fan of any deep air diving Instructor that thinks they can teach most students to progressively get good at 200 feet or deeper....as with drinking, some get this easy right away, and many others never will.
The real ability is not the skill. If you can deal with the narcosis, like the big drinker....then special skills will help.
The smart instructors teach Trimix for deep...Deep air should not be taught.
One reason I am NOT a fan of any deep air diving Instructor that thinks they can teach most students to progressively get good at 200 feet or deeper....as with drinking, some get this easy right away, and many others never will.
The real ability is not the skill. If you can deal with the narcosis, like the big drinker....then special skills will help.
The smart instructors teach Trimix for deep...Deep air should not be taught.
Was deep air ever taught? Learning to dive deep (a highly relative term) on air on Scuba is a very long and labor intensive process of self-discovery. Unfortunately, the basic physics and physiology required for the journey has been divided into half a dozen separate classes.
Trimix is appropriate after you have a very good idea of your personal limits, but it sucks for the vast majority of technical divers because their ability to treat bent divers or omitted decompression is limited to non-existent.
If technical diving is so safe then why is it illegal for commercial divers in many parts of world to make the same dive? Decompression dives on air to 50m/164' requires a chamber on site. Beyond that the diver must be on mixed gas and be working out of a bell and chamber system -- effectively Saturation Diving on HeO2 .
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How about knowing how to plan for a dive to that depth, carrying some redundancy and adequate gas supplies, some knowledge of decompression procedures, knowledge and use of trimix, and some ability to follow a proper deco schedule.
Either that or just use an oversize beer can, dump your ass overboard, swim like hell, and hope nothing goes wrong. Getting to 200 feet is easy, after all ... the tricky part is getting back to the surface in good health ...
... Bob (Grateful Diver)
Bob DBF
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From an end user point of view, my training (not to be confused with classes and certification) focused on staying alive, with an emphasis on aborting the dive for any reason at all. As the lesson went, planning the gas, being ready for deco, and having redundancy (which will be learned or else), dosent mean s**t if you don't learn to quit when anything seems off.
Since I'm no instructor, I don't really know how to explain the survival aspect of the training, except you have to learn when to quit. As Doppler said, a deep air instructor cannot teach most people to dive deep, I believe they should be teaching them when and how to quit.
Bob
Not figuring I actually made a point
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