Article from COMEX Scientific Director on rebreathers, decompression and Penny Glover

**nigelh** · 24th May 2006, 12:47

Quote: (Originally Posted by Mark Chase)

Still waiting for the reply thread but I am sure they can move this...

ditto.

He clearly has more information than we have seen but his scenario is an ox-tox dipping down to rescue her buddy.

So is the lesson we learn to do our deco on a buddy line? If my buddy starts to sink I pull on the line and a use my own bouyancy to pull them back to my level and then decide what to do.

I had not thought of this before nor heard it suggested but is it a good idea?

MattDuke · 24th May 2006, 13:02

Quote: (Originally Posted by nigelh)

ditto.

He clearly has more information than we have seen but his scenario is an ox-tox dipping down to rescue her buddy.

So is the lesson we learn to do our deco on a buddy line? If my buddy starts to sink I pull on the line and a use my own bouyancy to pull them back to my level and then decide what to do.

I had not thought of this before nor heard it suggested but is it a good idea?

What a tragic read. Is there anyway to check if these are facts?

It almost sounds like the diver sacrificed her life, to try and save her buddies (Who wasn't at the same skill level, or had an equipment failure)

Makes me feel so sad to think about that.

M.

jhaaja · 24th May 2006, 13:02

I say that it is very hard to keep the PO2 high if you start to descent. All the diluent you need to keep up the volume will dilute it.

JH

Ben Field · 24th May 2006, 13:03

Quote: (Originally Posted by nigelh)

So is the lesson we learn to do our deco on a buddy line? If my buddy starts to sink I pull on the line and a use my own bouyancy to pull them back to my level and then decide what to do.

I had not thought of this before nor heard it suggested but is it a good idea?

Am replying in relation to your post only, don't feel qualified to comment on the thread in general....

What happens if the opposite happens and they loose buoyancy control and have an uncontrolled ascent? Okay so you add a quick disconnect to the buddy line, not sure you'll find many buddies keen to be joined by a line while on deco either.

I wondered once if you couldn't make a BCD/wing/Drysuit/whatever buoyancy device you use that had a simple mechanical pressure switch inflate/deflate system such that once at a fixed depth on deco you could activate it and it would maintain your neutral buoyancy to the extent that you couldn't descend and only ascend slowly. Not sure thats a good idea either but at least it would avoid people "floating off" and you could always switch it off again I suppose.... anyway is a mute point because I couldn't work out how to make it work!

BEN

Mark Chase · 24th May 2006, 13:09

Quote: (Originally Posted by nigelh)

ditto.

He clearly has more information than we have seen but his scenario is an ox-tox dipping down to rescue her buddy.

So is the lesson we learn to do our deco on a buddy line? If my buddy starts to sink I pull on the line and a use my own buoyancy to pull them back to my level and then decide what to do.

I had not thought of this before nor heard it suggested but is it a good idea?

Yes I am starting to think clipping off to the station is a smart plan.

If Penny had an 02 spike on decent trying to catch her buddy, it will show on the printout of the Evo data log. It doesn't make a lot of sense as a rapid decent from 6 to 66m would involve a lot of ADV gas addition let alone a manual flush from Penny. I am confident that she would be running minimum loop on deco so it is hard to see this as a major issue.

When i want to go down quick on a YBOD it is instinctive to dump the wing and breath out through my nose/mouth to dump the counter lungs. In this case my first breath on decent is virtually all ADV

As YBOD divers we all jump in with 70% o2 in the counter lungs and descend on every dive?

I hear what the man is saying but it just doesn't add up.

ATB

Mark Chase

Mark Chase · 24th May 2006, 13:18

With regard to the main article, I feel (but this is just a feeling nothing more)the Comex data is based on task loaded divers working hard at depth. The data is relevant in some ways but I don't feel it compares with the sort of dive we generally do.

I have alway felt that working at depth is dangerous in terms of CNS, deco and most importantly C02. There is a good chance that C02 production, retention and related issues are a bigger threat to CCR divers than to OC divers. For this reason I treat big spidge at depth with a lot of respect.

ATB

Mark Chase

**nigelh** · 24th May 2006, 13:37

Quote: (Originally Posted by Mark Chase)

Yes I am starting to think clipping off to the station is a smart plan.

I like that more but it's not always possible

Quote:

If Penny had an 02 spike on decent trying to catch her buddy, it will show on the printout of the Evo data log. It doesn't make a lot of sense as a rapid decent from 6 to 66m would involve a lot of ADV gas addition let alone a manual flush from Penny. I am confident that she would be running minimum loop on deco so it is hard to see this as a major issue.

But this bases the problem on loop ppO2 and ox-tox is the big unknown. Exposure is a big factor and if they were using 100% at 6m to accelerate their exit, which may be more likely if their previous problem was not deco related, a sudden rise could be far more dangerous.

Quote:

When i want to go down quick on a YBOD it is instinctive to dump the wing and breath out through my nose/mouth to dump the counter lungs. In this case my first breath on decent is virtually all ADV.

but your blood tension could still be 1.6bar of O2.

I don't want to argue the theory. I felt that a simple tool could prevent needing to undertake emergency excursions like this. If my buddy suddenly started to sink I would not shrug my shoulders and say "I'm on 1.6bar/100% O2. I can't help" I'd do something so the use of a line makes sense. OK. If it is a sudden ascent I am dragged up, I help sort the problem and we bang back down to 6m. Frankly the surface is nasty but it's better than too deep because you stop at the surface.

Mark Chase · 24th May 2006, 13:58

Quote: (Originally Posted by Nigel)

I like that more but it's not always possibleBut this bases the problem on loop ppO2 and ox-tox is the big unknown. Exposure is a big factor and if they were using 100% at 6m to accelerate their exit, which may be more likely if their previous problem was not deco related, a sudden rise could be far more dangerous.but your blood tension could still be 1.6bar of O2.

I wouldn't dream of arguing the theory as I don't have the knowledge or the understanding. However I do have questions

Isn't the 02 in the blood metabolized pretty quickly? especially if your working to get down?

I know it right at the start of the CNS clock but I have often spent 20mins on the boat breathing 0.7 (70% 02) and then dropped to some quite considerable depths within a couple of mins. Wouldn't this also have the effect of spiking the PP02 of the 02 in the blood?

On the other issue. If there is no deco station to clip off to a big SMB or a lift bag will do. If the diver is any where near neutral a fully inflated crack bottle type SMB should do a pretty good job of holding him up.

Many moons ago when i felt i was going to pass out on deco (meigrane) I clipped off on my SMB reel.

Another good reason to use a ratchet type

ATB

Mark Chase

Mdemon · 24th May 2006, 14:32

Thank you for posting the translation - very interesting.

Bit of an ethical paradox here; keeping the safer tables secret is resulting in diver injury. I'd suggest that is a certainty. Releasing them will encourage divers to do riskier dives resulting in diver injury. I think that is also a certainty. They're damned if they do and damned if they don't. I'd rather they treated us like adults however and released the safer tables, even if just confidentially to the dive computer manufacturers...

Clipping off.

If you're clipped on, you have a chance.

Flame on...

NEwreckdiver · 24th May 2006, 14:43

I found this to be quite a provocative and interesting piece. For those interested in having a clean copy of this article, I made a quick PDF from a separate doc. Enjoy.

24th May 2006, 12:47	#11 (permalink)
nigelh New Member Current Rebreather/s: Inspiration Vision Other CCR Other Rebreather/s: Inspiration Classic Other CCR Join Date: Mar 2005 Location: Brighton, Sussex, UK Posts: 838	Re: Article from COMEX Scientific Director on rebreathers, decompression and Penny Glover Quote: (Originally Posted by Mark Chase) Still waiting for the reply thread but I am sure they can move this... ditto. He clearly has more information than we have seen but his scenario is an ox-tox dipping down to rescue her buddy. So is the lesson we learn to do our deco on a buddy line? If my buddy starts to sink I pull on the line and a use my own bouyancy to pull them back to my level and then decide what to do. I had not thought of this before nor heard it suggested but is it a good idea? __________________ nigelh
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24th May 2006, 13:02	#12 (permalink)
MattDuke New Member Current Rebreather/s: Not Bought Yet Other Rebreather/s: Inspiration Classic Not Bought Yet Join Date: May 2006 Location: Bergen, Norway Posts: 24	Re: Article from COMEX Scientific Director on rebreathers, decompression and Penny Glover Quote: (Originally Posted by nigelh) ditto. He clearly has more information than we have seen but his scenario is an ox-tox dipping down to rescue her buddy. So is the lesson we learn to do our deco on a buddy line? If my buddy starts to sink I pull on the line and a use my own bouyancy to pull them back to my level and then decide what to do. I had not thought of this before nor heard it suggested but is it a good idea? What a tragic read. Is there anyway to check if these are facts? It almost sounds like the diver sacrificed her life, to try and save her buddies (Who wasn't at the same skill level, or had an equipment failure) Makes me feel so sad to think about that. M.
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24th May 2006, 13:02	#13 (permalink)
jhaaja Custom Title Allowed! Current Rebreather/s: Inspiration Classic Other Rebreather/s: Join Date: Mar 2005 Location: Finland Posts: 884	Re: Article from COMEX Scientific Director on rebreathers, decompression and Penny Glover I say that it is very hard to keep the PO2 high if you start to descent. All the diluent you need to keep up the volume will dilute it. JH
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24th May 2006, 13:03	#14 (permalink)
Ben Field CK+Shearwater Current Rebreather/s: Classic Kiss Other Rebreather/s: Sport Kiss Join Date: Aug 2005 Location: London, England Posts: 1,621	Re: Article from COMEX Scientific Director on rebreathers, decompression and Penny Glover Quote: (Originally Posted by nigelh) So is the lesson we learn to do our deco on a buddy line? If my buddy starts to sink I pull on the line and a use my own bouyancy to pull them back to my level and then decide what to do. I had not thought of this before nor heard it suggested but is it a good idea? Am replying in relation to your post only, don't feel qualified to comment on the thread in general.... What happens if the opposite happens and they loose buoyancy control and have an uncontrolled ascent? Okay so you add a quick disconnect to the buddy line, not sure you'll find many buddies keen to be joined by a line while on deco either. I wondered once if you couldn't make a BCD/wing/Drysuit/whatever buoyancy device you use that had a simple mechanical pressure switch inflate/deflate system such that once at a fixed depth on deco you could activate it and it would maintain your neutral buoyancy to the extent that you couldn't descend and only ascend slowly. Not sure thats a good idea either but at least it would avoid people "floating off" and you could always switch it off again I suppose.... anyway is a mute point because I couldn't work out how to make it work! BEN __________________ Know your PPO2, Pre-breath, Use checklists, Validate cells at 6mtrs, Use pure O2 at or near surface, Use a BOV, Don't dive Solo, Change Slime and Cells as recommended by Manufacturer and RTFM! Beware Fridge Suck! www.hugsac.org.uk
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24th May 2006, 13:09	#15 (permalink)
Mark Chase I go down for ages Current Rebreather/s: Classic Kiss Other Rebreather/s: Inspiration Classic Join Date: Jan 2005 Location: Kent Posts: 2,700	Re: Article from COMEX Scientific Director on rebreathers, decompression and Penny Glover Quote: (Originally Posted by nigelh) ditto. He clearly has more information than we have seen but his scenario is an ox-tox dipping down to rescue her buddy. So is the lesson we learn to do our deco on a buddy line? If my buddy starts to sink I pull on the line and a use my own buoyancy to pull them back to my level and then decide what to do. I had not thought of this before nor heard it suggested but is it a good idea? Yes I am starting to think clipping off to the station is a smart plan. If Penny had an 02 spike on decent trying to catch her buddy, it will show on the printout of the Evo data log. It doesn't make a lot of sense as a rapid decent from 6 to 66m would involve a lot of ADV gas addition let alone a manual flush from Penny. I am confident that she would be running minimum loop on deco so it is hard to see this as a major issue. When i want to go down quick on a YBOD it is instinctive to dump the wing and breath out through my nose/mouth to dump the counter lungs. In this case my first breath on decent is virtually all ADV As YBOD divers we all jump in with 70% o2 in the counter lungs and descend on every dive? I hear what the man is saying but it just doesn't add up. ATB Mark Chase __________________ Is it supposed to make that noise ? I took my unit to the dive shop and demanded they bolt on every thing that would fit. Join my elite diving teem and get a Tshirt "Doing It Chasey"Hammerhead Eccr Advanced Diving System
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24th May 2006, 13:18	#16 (permalink)
Mark Chase I go down for ages Current Rebreather/s: Classic Kiss Other Rebreather/s: Inspiration Classic Join Date: Jan 2005 Location: Kent Posts: 2,700	Re: Article from COMEX Scientific Director on rebreathers, decompression and Penny Glover With regard to the main article, I feel (but this is just a feeling nothing more)the Comex data is based on task loaded divers working hard at depth. The data is relevant in some ways but I don't feel it compares with the sort of dive we generally do. I have alway felt that working at depth is dangerous in terms of CNS, deco and most importantly C02. There is a good chance that C02 production, retention and related issues are a bigger threat to CCR divers than to OC divers. For this reason I treat big spidge at depth with a lot of respect. ATB Mark Chase __________________ Is it supposed to make that noise ? I took my unit to the dive shop and demanded they bolt on every thing that would fit. Join my elite diving teem and get a Tshirt "Doing It Chasey"Hammerhead Eccr Advanced Diving System
(Online)

24th May 2006, 13:37	#17 (permalink)
nigelh New Member Current Rebreather/s: Inspiration Vision Other CCR Other Rebreather/s: Inspiration Classic Other CCR Join Date: Mar 2005 Location: Brighton, Sussex, UK Posts: 838	Re: Article from COMEX Scientific Director on rebreathers, decompression and Penny Glover Quote: (Originally Posted by Mark Chase) Yes I am starting to think clipping off to the station is a smart plan. I like that more but it's not always possible Quote: If Penny had an 02 spike on decent trying to catch her buddy, it will show on the printout of the Evo data log. It doesn't make a lot of sense as a rapid decent from 6 to 66m would involve a lot of ADV gas addition let alone a manual flush from Penny. I am confident that she would be running minimum loop on deco so it is hard to see this as a major issue. But this bases the problem on loop ppO2 and ox-tox is the big unknown. Exposure is a big factor and if they were using 100% at 6m to accelerate their exit, which may be more likely if their previous problem was not deco related, a sudden rise could be far more dangerous. Quote: When i want to go down quick on a YBOD it is instinctive to dump the wing and breath out through my nose/mouth to dump the counter lungs. In this case my first breath on decent is virtually all ADV. but your blood tension could still be 1.6bar of O2. I don't want to argue the theory. I felt that a simple tool could prevent needing to undertake emergency excursions like this. If my buddy suddenly started to sink I would not shrug my shoulders and say "I'm on 1.6bar/100% O2. I can't help" I'd do something so the use of a line makes sense. OK. If it is a sudden ascent I am dragged up, I help sort the problem and we bang back down to 6m. Frankly the surface is nasty but it's better than too deep because you stop at the surface. __________________ nigelh
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24th May 2006, 13:58	#18 (permalink)
Mark Chase I go down for ages Current Rebreather/s: Classic Kiss Other Rebreather/s: Inspiration Classic Join Date: Jan 2005 Location: Kent Posts: 2,700	Re: Article from COMEX Scientific Director on rebreathers, decompression and Penny Glover Quote: (Originally Posted by Nigel) I like that more but it's not always possibleBut this bases the problem on loop ppO2 and ox-tox is the big unknown. Exposure is a big factor and if they were using 100% at 6m to accelerate their exit, which may be more likely if their previous problem was not deco related, a sudden rise could be far more dangerous.but your blood tension could still be 1.6bar of O2. I wouldn't dream of arguing the theory as I don't have the knowledge or the understanding. However I do have questions Isn't the 02 in the blood metabolized pretty quickly? especially if your working to get down? I know it right at the start of the CNS clock but I have often spent 20mins on the boat breathing 0.7 (70% 02) and then dropped to some quite considerable depths within a couple of mins. Wouldn't this also have the effect of spiking the PP02 of the 02 in the blood? On the other issue. If there is no deco station to clip off to a big SMB or a lift bag will do. If the diver is any where near neutral a fully inflated crack bottle type SMB should do a pretty good job of holding him up. Many moons ago when i felt i was going to pass out on deco (meigrane) I clipped off on my SMB reel. Another good reason to use a ratchet type ATB Mark Chase __________________ Is it supposed to make that noise ? I took my unit to the dive shop and demanded they bolt on every thing that would fit. Join my elite diving teem and get a Tshirt "Doing It Chasey"Hammerhead Eccr Advanced Diving System
(Online)

24th May 2006, 14:32	#19 (permalink)
Mdemon SiegeEngine II Current Rebreather/s: Inspiration Classic Home Build Other Rebreather/s: Inspiration Classic Home Build Join Date: Feb 2007 Location: SWUK Posts: 1,927	Re: Article from COMEX Scientific Director on rebreathers, decompression and Penny Glover Thank you for posting the translation - very interesting. Bit of an ethical paradox here; keeping the safer tables secret is resulting in diver injury. I'd suggest that is a certainty. Releasing them will encourage divers to do riskier dives resulting in diver injury. I think that is also a certainty. They're damned if they do and damned if they don't. I'd rather they treated us like adults however and released the safer tables, even if just confidentially to the dive computer manufacturers... Clipping off. If you're clipped on, you have a chance. Flame on... __________________ www.southwestmafia.com "small minds talk about people, Average Minds Talk About Events, GREAT MINDS TALK ABOUT IDEAS!" The WRONG Attitude will get you killed. "Once the agenda-monkeys and perfect-worlders have moved on, perhaps we can do some diving?" Last edited by Mdemon : 24th May 2006 at 15:42. Reason: Too much info.
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