C02 retention

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Joshua Smith
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C02 retention

Post by Joshua Smith »

I found this video through a thread on TDS. It's amazing. It's from the DAN Tech diving conference in 2008. You need a DAN membership to view it, and you need to be registered on their site to watch it as well, but it's WELL worth the effort- DR. Simon Mitchel analyzes the video of Dave Shaw's final dive during the course of the absolute best explanation of the respiratory process and C02 elimination I have ever seen. This ought to be required viewing during every CCR class, IMO.

https://www.diversalertnetwork.org/Rese ... Video=D2_2
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HydroGirl
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Re: C02 retention

Post by HydroGirl »

Wow, he makes this complex subject simple and clear.
He is so right about how we (diver) always blame the scrubber. Last Saturday I had a funny even happen to me and my first response was, it must be the scrubber.
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Re: C02 retention

Post by Waynne Fowler »

HydroGirl wrote:Last Saturday I had a funny even happen to me and my first response was, it must be the scrubber.
I don't rebreath but found the vid very informative. HydroGirl... if you wouldn't mind, could you elaborate a bit as to this 'funny even(t)' that happened. I'm more than interested providing it is a subject that can be brought up in this venue.
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Re: C02 retention

Post by ArcticDiver »

Excellent presentation by an intelligent and knowledgeable person. He spoke to express; not to impress. Thanks for posting the link.
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Re: C02 retention

Post by HydroGirl »

Did anyone else find the Dave Shaw video difficult to watch?
I have to agree with Joshua, this should be required not just for CCR divers but all tech divers.

Waynne,
I will PM my answer.
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Re: C02 retention

Post by Joshua Smith »

HydroGirl wrote:Did anyone else find the Dave Shaw video difficult to watch?
I have to agree with Joshua, this should be required not just for CCR divers but all tech divers.

Waynne,
I will PM my answer.
I've been fascinated with Dave Shaw's life and death for years. I read this Excellent Article about him before I started diving, and I read the also very good book "Raising the Dead" later, but I never really felt like I understood what, exactly killed him until I saw this video. I sort of accepted the explanation that he was too deep and that C02 got him, and maybe he had the wrong scrim on his scrubber, and maybe the sorb was the wrong grade, etc. without really grasping it. Dr. Mitchell provided what I must say is the most likely cause of death, and did it in such a straightforward and logical way that it kind of blew my mind. At those kinds of depths, the margin between life and death is razor thin. Yes, maybe those minor details in Shaw's kit increased his work of breathing by .03%, which started the smallest bit of C02 retention, and from that moment on, he was in a death spiral. I kept wondering if his scrubber had failed- but as Mitchell pointed out- the scrubber very likely didn't ever get a shot at scrubbing the C02 that killed him.
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Re: C02 retention

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As life would have it a couple months after he died the guy in the seat next to me on a flight was one of Shaw's co-workers. It was very interesting to hear about his life details and to put that in context of his adventures and his death. One of the things we discussed was how CO2 had been the proximate cause of his death, not equipment difficulties. By the end of the flight I had a real appreciation for the man and his passionate hobby.

At the same time we have to recognize that in many cases of what we call "tech diving" it is the choice of equipment for the proposed task is what creates the very narrow margins between life and death or injury. I'm not criticizing people's choices. It is just that it is important to recognize that those choices bring with them risks that different choices would either eliminate or reduce.
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Re: C02 retention

Post by kdupreez »

As a South African expat, I have met and know a lot of the people in the small tec diving community in South Africa involved with the recovery of Deon Dreyer's body from 900ft in bushman's hole and the subsequent death of David Shaw and all his deep and penetration training and diving in SA with Don Shirley leading up to it.. Its all very well documented in a book called "Raising the dead"

The book in SA is called "Raising the dead", but here in the USA its called "Diving into Darkness".. The book very accurately details David's life, training, experience and death (Although not much about the subsequent death investigation.) I have a couple of copies if anyone wants to read it..



I can VERY highly recommend this book to any Experienced, Noob or wannabe Tec or CCR diver.. well worth the read.

It is my opinion however that there were a lot of screw ups on that dive that should NEVER have happened and with things like that cascading and drawing you deeper into the incident pit, the dive should have been aborted..

There was a LOT of pressure from the media, public, peers and Deon's parents on the team to get it done.. Horrible stuff that should have them called the dive included the emergency hoisting system getting divers out bushman's hole was a complete F'up.. The failure and dismantling of a primary VR3's the night before the dive (sticking tin-foil in battery chambers... modifying VR3's by filling with paraffin and emptying into freegin coffee cup and pouring it back the night before..) etc.. you hear these things from first hand accounts and read them in the book and you can just shake your head that this dive actually took place..

The worst mistake IMHO was the un-publisiced fact that David (a very in-experienced diver, with his last dive being career dive no. 333 post his OW cert to 900ft.. WTF!) was diving with a heavily modified Mk15.5 rebreather and that he packed his own sorb and opted to use denser type scrubbing media than what was recommended to him for a 900ft dive.. WOB with denser sorb at 900 freegin feet is nothing short of stupid.. The huge radial scrubber in the MK15.5 performs extremely well at great depths, even better than any RB on the market today.. but it doesn't make it invincible against simple physics..

Anyhow, INCERDIBLE book to read if you ever think about Tec diving.. rule and priority no.1 is for the team to come back unscathed.. this was secondary and even an afterthought on this dive IMHO.

(These are my opinions and don't necessarily reflect the opinions of the people on that dive. For the record; my intent here is NOT to start a debate :smt064 )

PS. here is David Shaw's web site as he designed and updated it himself.. nothing was changed since he last updated it : http://www.deepcave.com


.
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Re: C02 retention

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kdupreez wrote:As a South African expat, I have met and know a lot of the people in the small tec diving community in South Africa involved with the recovery of Deon Dreyer's body from 900ft in bushman's hole and the subsequent death of David Shaw and all his deep and penetration training and diving in SA with Don Shirley leading up to it.. Its all very well documented in a book called "Raising the dead"

The book in SA is called "Raising the dead", but here in the USA its called "Diving into Darkness".. The book very accurately details David's life, training, experience and death (Although not much about the subsequent death investigation.) I have a couple of copies if anyone wants to read it..



I can VERY highly recommend this book to any Experienced, Noob or wannabe Tec or CCR diver.. well worth the read.

It is my opinion however that there were a lot of screw ups on that dive that should NEVER have happened and with things like that cascading and drawing you deeper into the incident pit, the dive should have been aborted..

There was a LOT of pressure from the media, public, peers and Deon's parents on the team to get it done.. Horrible stuff that should have them called the dive included the emergency hoisting system getting divers out bushman's hole was a complete F'up.. The failure and dismantling of a primary VR3's the night before the dive (sticking tin-foil in battery chambers... modifying VR3's by filling with paraffin and emptying into freegin coffee cup and pouring it back the night before..) etc.. you hear these things from first hand accounts and read them in the book and you can just shake your head that this dive actually took place..

The worst mistake IMHO was the un-publisiced fact that David (a very in-experienced diver, with his last dive being career dive no. 333 post his OW cert to 900ft.. WTF!) was diving with a heavily modified Mk15.5 rebreather and that he packed his own sorb and opted to use denser type scrubbing media than what was recommended to him for a 900ft dive.. WOB with denser sorb at 900 freegin feet is nothing short of stupid.. The huge radial scrubber in the MK15.5 performs extremely well at great depths, even better than any RB on the market today.. but it doesn't make it invincible against simple physics..

Anyhow, INCERDIBLE book to read if you ever think about Tec diving.. rule and priority no.1 is for the team to come back unscathed.. this was secondary and even an afterthought on this dive IMHO.

(These are my opinions and don't necessarily reflect the opinions of the people on that dive. For the record; my intent here is NOT to start a debate :smt064 )

PS. here is David Shaw's web site as he designed and updated it himself.. nothing was changed since he last updated it : http://www.deepcave.com


.

I agree 100% about the media pressure and the other questionable motivations to do these dives. I'm currently reading Verna Von Shaik's book Fatally Flawed, and her account of trying to be the record holder for depth is sobering. It reflects a mentality that, I think, is mostly not present in sport diving today.

And, fwiw- Shaw and Shirley were diving Hammerheads, not VR-3s. Neither of which are being used by any serious deep divers today, afaik. Not that the hardware in question killed Shaw or bent Shirley, for that matter. These guys are still teaching the rest of us a lot. My own conclusions are that CCRs are probably the tools of choice for the diver seeking to explore depths from +/- 250' to 600'. 600' sems to be the area where we enter into the "crazy-ass, hope it works" realm of scuba- both ccr and oc. Deeper than that can, and has been, done with surfaced supplied gas. And deeper than that should be done with a submarine, or ROV.
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Re: C02 retention

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Joshua Smith wrote:And, fwiw- Shaw and Shirley were diving Hammerheads, not VR-3s.
He retrofitted hamerheads for CCR PO2 monitoring and solenoid control, but he was diving VR3's for deco.. He had 2x VR3's on his right wrist.. one of which already imploded during the dive.. you can see that in the video as well..

But yeah, lots and lots of lessons to be learnt here for sure. waaay too many variables and waay too many shit going wrong for such an un-experienced diver to attempt this dive..

I remember a lot of people close to the incident complaining about the last minute decision to mount a camera on Shaws head, he had zero experience with that piece of equipment.. supposedly Shaw also had a bad habit of when removing his light, he would drape it around head his head like you do a 7ft hose, instead of clipping it off, (EDIT: Laura explained to me via email why the "light cord around the neck" was accepted and taught in cave diving for many years.. its so you can still point the light at something you need to do and have both hands free.. that explains the behaviour.. ) In this case he actually dropped his light on the bottom (you can see it in the video too) because of the camera on his head was in the way of hanging it over his neck as usual and his light cord is what got caught in the line when he tried to leave. he dragged Deon's body for a long while stuck on the light cord. working that hard at 900ft dragging a body through the mud and the dense sorb in his MK15.5 let him CO2 out.

Also AFAIK, there were shot lines from Nuno Gomez's record OC dive, another shot line left from Verna Van Schaik's 725ft record OC dive a month or so prior AND Shaw's shot line for the body recovery and Shaw's line he left there tied to the body on the previous discovery dive.. WTF? all that in itself was an accident waiting to happen... its unclear if he got stuck in his own or Verna Van Schaik's line on the way back.. he was pretty tangled up in line when the body surfaced..

when Shaw's body was found stuck to the cave roof the next day, he was found with Deon's 10 year old headless, handless, feetless soapified remains still tangled hanging by Shaw's light cord..

You should really read the book, I'll give it to you.. its frighting to read all the stuff and talk to the people who were there and you can only bang you head against a wall asking yourself how people could in good conscious let that dive continue.

.
Last edited by kdupreez on Mon Feb 28, 2011 8:12 pm, edited 2 times in total.
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Re: C02 retention

Post by ArcticDiver »

kdupreez wrote:
Joshua Smith wrote:And, fwiw- Shaw and Shirley were diving Hammerheads, not VR-3s.
He retrofitted hamerheads for CCR PO2 monitoring and solenoid control, but he was diving VR3's for deco.. He had 2x VR3's on his right wrist.. one of which already imploded during the dive.. you can see that in the video as well..

But yeah, lots and lots of lessons to be learnt here for sure. waaay too many variables and waay too many shit going wrong for such an un-experienced diver to attempt this dive..

I remember a lot of people close to the incident complaining about the last minute decision to mount a camera on Shaws head, he had zero experience with that piece of equipment.. supposedly Shaw also had a bad habit of when removing his light, he would drape it around head his head like you do a 7ft hose, instead of clipping it off, (why the F$# he did that, only he knows).. In this case he actually dropped his light on the bottom (you can see it in the video too) because of the camera on his head was in the way of hanging it over his neck as usual and his light cord is what got caught in the line when he tried to leave. he dragged Deon's body for a long while stuck on the light cord. working that hard at 900ft dragging a body through the mud and the dense sorb in his MK15.5 let him CO2 out.

Also AFAIK, there were shot lines from Nuno Gomez's record OC dive, another shot line left from Verna Van Schaik's 725ft record OC dive a month or so prior AND Shaw's shot line for the body recovery and Shaw's line he left there tied to the body on the previous discovery dive.. WTF? all that in itself was an accident waiting to happen... its unclear if he got stuck in his own or Verna Van Schaik's line on the way back.. he was pretty tangled up in line when the body surfaced..

when Shaw's body was found stuck to the cave roof the next day, he was found with Deon's 10 year old headless, handless, feetless soapified remains still tangled hanging by Shaw's light cord..

You should really read the book, I'll give it to you.. its frighting to read all the stuff and talk to the people who were there and you can only bang you head against a wall asking yourself how people could in good conscious let that dive continue.

.
Making the assumption that what I was told about Shaw is accurate; how was anyone going to stop the dive? Over my life, in a different arena, I've participated in adventures for adventure sake. When people get in that mind set it takes someone outside the loop to intervene. From what has been made publicly available there was no one outside the loop. There was no "company manual" for the Captain and crew. Although the risks may have been imperfectly understood it appears that the risks were analysed and accepted, especially by the key player and supporting actors.

I have no problem with tough, even brutal, after the fact analysis. That is something that has proven beneficial over the years. But, to say that someone somehow was unethical because they didn't stop this dive flies in the face of common sense.

One person made a comment that for all the money and effort that went into this dive it could have been done hard hat with usual support with very little risk to anyone. IF that is true then this truely was an adventure dive for adventure's sake and should be analysed as such.
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Re: C02 retention

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ArcticDiver wrote:Making the assumption that what I was told about Shaw is accurate; how was anyone going to stop the dive? Over my life, in a different arena, I've participated in adventures for adventure sake. When people get in that mind set it takes someone outside the loop to intervene. From what has been made publicly available there was no one outside the loop. There was no "company manual" for the Captain and crew. Although the risks may have been imperfectly understood it appears that the risks were analysed and accepted, especially by the key player and supporting actors.
You make an absolutely valid point, in the face of adventure, even adversely so, human nature will prevail
ArcticDiver wrote: I have no problem with tough, even brutal, after the fact analysis. That is something that has proven beneficial over the years. But, to say that someone somehow was unethical because they didn't stop this dive flies in the face of common sense.

One person made a comment that for all the money and effort that went into this dive it could have been done hard hat with usual support with very little risk to anyone. IF that is true then this truly was an adventure dive for adventure's sake and should be analyzed as such.
There was many people for and many people against the dive, but you are right, for the pure sake of adventure this was the decision and ultimately the sacrifice by the key players. I might not agree with it and I might voice concerns in in analyzing the transpired events, you are definitely right and even if someone would have said or done things to stop them, he/she would probably have been ostracized and there would have been no change in the outcome of this dive..
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Re: C02 retention

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I just read this book about David Shaw, "Diving into Darkness". I think it may be printed overseas as "Bringing back the Dead".

I found his story fascinating on a number of levels. The fact that Shaw did these dives is amazing, but how fast his curve from novice diver to diving to 270m is mind blowing. During the stretch with Don Shirley's fight for survival I couldn't put the book down.

In addition to the book there are other sources of info about Shaw that made this story even more interesting. Besides the Dan conference, Shaw's website and dive reports are still available. You can still find threads on other forums that occured while the real drama was unfolding. The actual video from his helmet cam is worth watching, I thought watching it would harder but I found it interesting.

I realize this is an old thread but if you enjoy dive adventure stories this is worth reading.
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Re: C02 retention

Post by Mortuus »

Is there another link to this video somewhere? As a diver who plans to move into tech diving within the year, I have become naturally curious about CO2 retention and elimination (thus being attracted to this topic to begin with). I would love to watch this if anyone knows where I can find it
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Re: C02 retention

Post by Joshua Smith »

It took some digging, and I can't link directly to it, but go here:

https://www2.dan.org/FastAccess/2008Tec ... iving.aspx

And log in as a DAN member (or non member, it looks like) (And if you don't have DAN insurance, you probably shouldn't be tech diving, just sayin'.)

THEN- scroll down. You want the video from the 2008 tech diving conference, day 1, morning, Physiology workshop, Respiration-Mitchel

Convoluted path, but worth doing.
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Re: C02 retention

Post by Mortuus »

Will do, when i get back to my house. Thanks for the digging! I do have DAN insurance. Isnt it required to get tech certified anyways? At least with GUE it is
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Re: C02 retention

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Mortuus wrote:Will do, when i get back to my house. Thanks for the digging! I do have DAN insurance. Isnt it required to get tech certified anyways? At least with GUE it is
No, its strongly suggested, but not a.requirement with TDI or IANTD. At least it wasn't when I got certs from them. Don't know about PADI.
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Re: C02 retention

Post by Mortuus »

Just had the pleasure of watching the video. That was an amazing lecture! The diagrams and explanations were very efficient at making it comprehendable to laymen
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