Per Capita which kills more?Deep Air or RBs
- Thread starter 100days-a-year
- Start date
Please register or login
Welcome to ScubaBoard, the world's largest scuba diving community. Registration is not required to read the forums, but we encourage you to join. Joining has its benefits and enables you to participate in the discussions.
Benefits of registering include
- Ability to post and comment on topics and discussions.
- A Free photo gallery to share your dive photos with the world.
- You can make this box go away
- Messages
- 13,509
- Reaction score
- 10,177
- Location
- Port Orchard, Washington State
- # of dives
- 1000 - 2499
The key word is "aggressive" waymoreso than recreational. There are plenty of OC tech diving fatalities too, they tend to be less publicized. I suspect because the community of 200ft tropical air divers is much larger and also less wired than the community of CCR divers who tend to have a higher degree of connectiveness. So we hear about the latter more.
Damn internet.....
hg frogman
Contributor
1) One has to be quite dumb to dive deep air with a CCR ... given the price of the CCR, and of the training, vs the price of Helium and the quantities of Helium needed for CCR diving ... so no need to spend much saliva about this. These two items are not interconnected.
2) At least one woman killed using a CCR : Penelope Glover. There are others but I keep no list.
3) About fatalities using a CCR. There was an interesting article from Dr Gardette (Scientific Director of the French commercial diving company Comex) that created a controversy in the French CCR community. This article was published in April 2006 in SUBAQUA, official magazine of the French Diving Federation (FFESSM). You can find it (but in French) with some Googling.
This article followed the death of Penelope Glover and her student after a CCR Trimix dive with a bottom time of 40' at 80 meters/267 feet. They were found drowned after having spent some time at the 6 meters/20 feet stop.
Dr Gardette said this accident was "the last straw" that made him want to express his concern about the too many fatalities occurring with leisure CCRs (many less fatalities amongst the militaries). According to him, the problems didn't arise so much from the reliability of the CCRs (at least from the CCR Glover was using), nor from the ability of the divers using them (eg control of the ascent and deco stops). The main issue came from the CCRs affording (gas-wise) way too much bottom time to leisure divers.
He said that the models available for deco don't match these very extended bottom times. He acknowledged that even the current Comex tables for Trimix led to 1% (one percent) occurrence of DCS hits (same as "severe" air dives) yet they were more conservative than many deco sofwares you could find on the Net. He finally suggested that 20' at 60 meters/200 feet for Air, and 15' at 80 meters/267 feet for Trimix, should be considered as the bottom-time limits for leisure (ie neither military nor commercial) deep diving.
CCRs adepts reacted angrily and said he was being much too restrictive.
I found the controversy stimulating, and I don't have the answer yet : for me the debate is still open. Yet, when I read reports about "deco on the fly" made by divers from a younger generation, I cannot prevent myself thinking, "Wow, these are the tough bunch" ... ironically, that's exactly what some of these younger heroes think (and say) about the older generations diving "deep" with air
.
2) At least one woman killed using a CCR : Penelope Glover. There are others but I keep no list.
3) About fatalities using a CCR. There was an interesting article from Dr Gardette (Scientific Director of the French commercial diving company Comex) that created a controversy in the French CCR community. This article was published in April 2006 in SUBAQUA, official magazine of the French Diving Federation (FFESSM). You can find it (but in French) with some Googling.
This article followed the death of Penelope Glover and her student after a CCR Trimix dive with a bottom time of 40' at 80 meters/267 feet. They were found drowned after having spent some time at the 6 meters/20 feet stop.
Dr Gardette said this accident was "the last straw" that made him want to express his concern about the too many fatalities occurring with leisure CCRs (many less fatalities amongst the militaries). According to him, the problems didn't arise so much from the reliability of the CCRs (at least from the CCR Glover was using), nor from the ability of the divers using them (eg control of the ascent and deco stops). The main issue came from the CCRs affording (gas-wise) way too much bottom time to leisure divers.
He said that the models available for deco don't match these very extended bottom times. He acknowledged that even the current Comex tables for Trimix led to 1% (one percent) occurrence of DCS hits (same as "severe" air dives) yet they were more conservative than many deco sofwares you could find on the Net. He finally suggested that 20' at 60 meters/200 feet for Air, and 15' at 80 meters/267 feet for Trimix, should be considered as the bottom-time limits for leisure (ie neither military nor commercial) deep diving.
CCRs adepts reacted angrily and said he was being much too restrictive.
I found the controversy stimulating, and I don't have the answer yet : for me the debate is still open. Yet, when I read reports about "deco on the fly" made by divers from a younger generation, I cannot prevent myself thinking, "Wow, these are the tough bunch" ... ironically, that's exactly what some of these younger heroes think (and say) about the older generations diving "deep" with air
.
Last edited:
Dr Gardette said this accident was "the last straw" that made him want to express his concern about the too many fatalities occurring with leisure CCRs (many less fatalities amongst the militaries). According to him, the problems didn't arise so much from the reliability of the CCRs (at least from the CCR Glover was using), nor from the ability of the divers using them (eg control of the ascent and deco stops). The main issue came from the CCRs affording (gas-wise) way too much bottom time to leisure divers.
I found the controversy stimulating, and I don't have the answer yet : for me the debate is still open. Yet, when I read reports about "deco on the fly" made by divers from a younger generation, I cannot prevent myself thinking, "Wow, these are the tough bunch" ... ironically, that's exactly what some of these younger heroes think (and say) about the older generations diving "deep" with air
Interesting point about the increased time for CCR divers. A dive buddy of mine in Hawaii went to diving a CCR and he started doing 3 hour solo shore dives to a wreck at 120'. It was a bit jaw dropping hearing him describe it knowing his background and his in water skills.
To the point about "deco on the fly". Just because someone says they are doing ratio deco doesnt mean that what they are doing has anything to do with ratio deco. From a GUE standpoint its plan your dive, dive your plan. Use ratio deco to calculate your dive ahead of time, plan for contingency. IMO the only time you do ratio deco in the water is if things go really wrong. Some people will disagree with that but for novice tech divers such as myself deco on the fly can cause trouble if you try using it in the water.
Reg Braithwaite
Contributor
I doubt the sample sizes we have for RB and Deep Air fatalities are large enough to be statistically significant, even when they agree with my prejudices. Once you try to normalize for other factors, you are left with what amounts to anecdotal evidence. As noted above, you really should normalize for depth and conditions. A RB death at 300' is not the same thing as a deep air death at 240'. A RB death in a cave is not the same thing as a deep air death in a wreck.
And finally, you can spin statistics wonderfully to demonstrate a point. Say that one deep air divers is killed every million dives, and further say that two rebreather divers are killed every million dives.
One person claims the rebreathers are twice as dangerous as deep air. Another claims they are only 0.0001% less safe. Who is correct?
And finally, you can spin statistics wonderfully to demonstrate a point. Say that one deep air divers is killed every million dives, and further say that two rebreather divers are killed every million dives.
One person claims the rebreathers are twice as dangerous as deep air. Another claims they are only 0.0001% less safe. Who is correct?
wrybosome
Contributor
According to PBS's Nova: Extreme Cave Diving 1 in 10 rebreathers will kill you...
- Messages
- 13,509
- Reaction score
- 10,177
- Location
- Port Orchard, Washington State
- # of dives
- 1000 - 2499
That's for a particular make/model which wasn't even used on the show. That bit was purely for TV drama.
hg frogman
Contributor
Dr Gardette (see my previous post) just issued the results of a new survey, with updates of his "recommended maximum bottom time values". They are published with the title "Nouvelle Theorie de la Decompression : Analyse du Risque en Plongee" in the French dive magazine Octopus (new version), n°2, January-March 2010.
From extensive statistic research, he associates the severity of the dive (= depth in meters x sqrt of the bottom time in minutes) with the statistical occurrence of DCS (noted DCS%). He also takes into account the inert gas (N2 or He) and the level of Doppler recorded bubbles.
He says that, for the same severity of the dive, DCS% is the half with Helium than with N2.
About the limits that he's suggesting now for leisure technical diving (ie, neither military nor commercial) :
For Deep Air diving (severity = 270, DCS% = 3/1000) these limits are 45' at 40 meters, or 30' at 50 meters, or 20' at 60 meters.
For Heliox diving (severity = 450, DCS% = 1/100) these limits are 30' at 80 meters, 20' at 100 meters, and 15' at 120 meters.
According to him, the risk taken (DCS%) can be reduced by increasing deco time. For example, a diver doing a 20' dive at 100 meters with Helium (DCS% = 1%, severity = 450) can divide the risk by three and bring it down to 0.3% (making the dive equivalent to severity = 350 ie 12' at 100 meters) by increasing his total deco time by 50 % (from 3 hours to 4 hours 30 minutes).
Read the original article for more details. There is much more in it than in this post.
PS: in my previous post I forgot to mention than, according to Dr Gardette, the most likely cause of Glover's and her student's deaths while diving CCRs was DCS of the student, followed by oxtox of Glover trying to rescue the sinking student.
Disclaimer : this is an approximate translation of bits of an article in a French magazine. Take this as food for thought but not as recommended practice for actual diving.
From extensive statistic research, he associates the severity of the dive (= depth in meters x sqrt of the bottom time in minutes) with the statistical occurrence of DCS (noted DCS%). He also takes into account the inert gas (N2 or He) and the level of Doppler recorded bubbles.
He says that, for the same severity of the dive, DCS% is the half with Helium than with N2.
About the limits that he's suggesting now for leisure technical diving (ie, neither military nor commercial) :
For Deep Air diving (severity = 270, DCS% = 3/1000) these limits are 45' at 40 meters, or 30' at 50 meters, or 20' at 60 meters.
For Heliox diving (severity = 450, DCS% = 1/100) these limits are 30' at 80 meters, 20' at 100 meters, and 15' at 120 meters.
According to him, the risk taken (DCS%) can be reduced by increasing deco time. For example, a diver doing a 20' dive at 100 meters with Helium (DCS% = 1%, severity = 450) can divide the risk by three and bring it down to 0.3% (making the dive equivalent to severity = 350 ie 12' at 100 meters) by increasing his total deco time by 50 % (from 3 hours to 4 hours 30 minutes).
Read the original article for more details. There is much more in it than in this post.
PS: in my previous post I forgot to mention than, according to Dr Gardette, the most likely cause of Glover's and her student's deaths while diving CCRs was DCS of the student, followed by oxtox of Glover trying to rescue the sinking student.
Disclaimer : this is an approximate translation of bits of an article in a French magazine. Take this as food for thought but not as recommended practice for actual diving.
Last edited:
Relevance to CCR? This article seems to be positioning a 'new theory for decompression, analysis of risks in diving'. While interesting, not specific to CCR as we are discussing here.
Similar threads
