Mouthpiece Retaining Head-strap

I'd second Paul, and state in addition that the combination of a gag strap and a BOV makes for an easy prospect of training open circuit divers how to respond to an unconcious RB diver... protect the airway and twist the knob.

As far as hypoxia is concerned: I've probably gotten more experience watching others go thru the evolution of incipient hypoxia thru total loss of conciousness while participating in high altitude chamber training at "the day job" than anyone else around. At 25,000 feet pressure altitude in the hypobaric (altitude) chamber, it typically takes about 3-4 minutes to become unconcious after removal of 02 mask. Symptoms vary, but in the middle stages, the subjects are partially responsive and will "smile and wave" but CANNOT assist in their own recovery. They will gesture back when you yell "PILOT, PUT ON YOUR MASK! PILOT YOU ARE GOING TO DIE IF YOU DON'T PUT ON YOUR MASK... PUT ON YOUR MASK NOW!!! " but instead will sit there stupidly doing whatever puzzle they have been given (usually a simple drawing puzzle) until total loss of conciousness occurs. The bottom line is that in that "middle zone" between conciousness and loss of conciousness, there is a grey area in which rote level work can still be done (IE simple repetitive things) but there is no conciousness available for self rescue. I've seen this literally hundreds of times. After they are assisted onto their masks, there will be complete amnesia, with no recollection at all of the event. The good news, if there is any, is that it would be a gentle way to die... but please don't try to prove it the hard way.

The takeaway is that you might SEEM to be OK to a buddy, IE: you might still be finning along the wreck... LONG after you have lost your ability to self rescue. That gag strap BOV combination is the ONLY way to really get a quick recovery assistance from a buddy while protecting the airway.

Pic was taken on a course that I wrangled for a bunch of civilian pilots as a demonstration, that's me grinning stupidly at front right, 25,000 feet after about two minutes. Feels like a good Margarita buzz at that time. The guys standing in the back are the tenders, it looks like the door is open, but that's the door into the transfer lock.

This type of training is invaluable. We also did it with ROBS (reduced oxygen breathing system) flying a simulator while the trainers slowly reduce the fraction of 02 in the mix you are breathing. I taught that course for almost 10 years... it was VERY interesting work. I now do it as part of advanced rebreather training, with a self made ROBS system here in the Little Diveshop of Horrors. If anyone wants a demo, feel free to come by.



Dave

.
 

Attachments

  • dsaltitudechamber[1].jpg
    dsaltitudechamber[1].jpg
    86.6 KB · Views: 122
Dave1w said:
I ordered a strap from AP Valves and it arrived quickly enough for me to give it a go this weekend over a few dives. It was easy enough to fit and my thoughts were to use it with an Aqualung lip shield thing similar to the rEvo setup.

I had mixed results. The strap itself was actually better than I imagined for the price with a solid crown piece and two straps that each had a large o-ring on the end which went around your breathing hose.

I am using a Golem Shrimp on my Classic Kiss, and when it was all attached up it was nice and secure, but due ( I think) to the shape of the Shrimp, and the angle up to the crown, it seemed to push the shrimp into my mask, which resulted in pretty bad mask flooding. I tried with and without the lip shield, and had some success by dropping the strap down to the back of my head. I am sold on the idea, but will need to do a bit of fiddling I think to get it working properly for me.

The strap on the ALBOV on my APOC does the job well and pulls from below the centreline I think, so no interference with the mask.

I actually have Drager Ray hoses on my Kiss, and they are that bit tighter, allowing me to not bite down while still holding a good seal, with the lip shield it was even better, but the mouthpiece is a little short to have that on comfortably, so Maybe I'll try a different mouthpiece.

I will try and get it sorted, as I do think the strap is a good safety item.


Sent from my iPad using Tapatalk HD
Click to expand...

I used the Draeger Crown Strap on both the old style Golem VARIO BOV and Golem Shrimp, and it works, while others which I have tried don't.

I believe it works because of the particular design of the Draeger BOV which allows for a particular (the right one) fixed angle of pull and such force also being applied to the mouthpiece itself, and not the DSV/BOV.

German technology in this case proves a winner.

As to the thread, I can only echo the comments of Paul and Dave, because the Golem BOV with Crown Strap saved my life once (thank-you Jakub!!!). I would not be here if I did not have the arrangement.

I placed the fresh recount of the incident at the time on the DIRrebreather forum (so that may be a more accurate recount of what I am writing here by memory some years having elapsed).

I was in a cave in a very familiar large section which I had been through several several times (not a new experience or novelty).

I felt though like that specific place I was in was narrow and dark, and I told myself it was not. I looked and it was neither narrow and dark and it was the same exact place I often go through... but I was having this sensation of oppression and being in a narrow and dark place and somewhere I should not be (to which I promptly responded telling myself not to be an idiot because that is where I had exactly chosen to be, my choice to be there, and been there before, and done that).

At any rate, at the "emotional" level feeling not right, purely as a precaution, and not on the basis of any rationale, I flicked the Golem BOV to OC (my pPO2 changed from 1.3 to about 0.5).

After about 3 breaths, 3 normal breaths, my breathing rate went through the roof - a full CO2 hit.

I turned around and proceeded to exit the cave. My vision had narrowed down like I was looking through a pinhole (not a peeping hole, literally a pinhole). All I could see was the blu permanent cave line, which I was following, but only the line, I had lost perception of everything except the line.

I was not in panic, but I was breathing like a rapist and all I could see was the blue cave line, which hopefully I was now following towards the exit (as opposed to away from the exit). I had no bearing or awareness of the cave like I normally have.

There is a place along the line which I know very well and which had another line crossing above the main line... so I had to go below that line above to follow the main line.

Of course I had no perception of where I was and the surroundings, so with the frog kick I managed to put a perfect turn of the line (a locking loop) above me around my ankle. I was stuck and breathing like a rapist and had the narrowest of the narrow tunnel visions.

I was living the experience without panic as if I was not there myself and at that point I thought: "So, this is how people die in caves."

Lowered my right shoulder, reached with my left hand for the ankle, and removed the loop. I was lucky my tank valves did not get caught in the main line below me (I have the rebreather tanks facing up towards the head).

The WOB was so heavy that at one point I considered going back to the loop by flicking the BOV back to CC position. I did not, and continued to follow the line out (presumably at that point). I was in no position to switch to my OC reg on the necklace (my BOV was attached to a 10 liter tank, so had not yet run out of gas).

It was very nice to see the light of the cave exit and get out.

When I got home I analysed the dive. I had the trace from the dive computer log, and knew approximately the tank pressure at the time of the incident.

Fortunately, I was only 150 meters inside the cave. It took about 6 minutes to exit (it was not a graceful exit, but I do not believe I damaged the cave which was nice). To my surprise, my ascent rate was spot on 9 meters/minute. The SAC rate of the exit was 60 liters/minute.

Had I not flicked that BOV to OC when I did and if it were not there on a quality Crown Strap to hold it in place and connected to a large supply of gas, I do not think I'd be here.
 
Last edited:
Dave Sutton said:
I'd second Paul, and state in addition that the combination of a gag strap and a BOV makes for an easy prospect of training open circuit divers how to respond to an unconcious RB diver... protect the airway and twist the knob.

As far as hypoxia is concerned: I've probably gotten more experience watching others go thru the evolution of incipient hypoxia thru total loss of conciousness while participating in high altitude chamber training at "the day job" than anyone else around. At 25,000 feet pressure altitude in the hypobaric (altitude) chamber, it typically takes about 3-4 minutes to become unconcious after removal of 02 mask. Symptoms vary, but in the middle stages, the subjects are partially responsive and will "smile and wave" but CANNOT assist in their own recovery. They will gesture back when you yell "PILOT, PUT ON YOUR MASK! PILOT YOU ARE GOING TO DIE IF YOU DON'T PUT ON YOUR MASK... PUT ON YOUR MASK NOW!!! " but instead will sit there stupidly doing whatever puzzle they have been given (usually a simple drawing puzzle) until total loss of conciousness occurs. The bottom line is that in that "middle zone" between conciousness and loss of conciousness, there is a grey area in which rote level work can still be done (IE simple repetitive things) but there is no conciousness available for self rescue. I've seen this literally hundreds of times. After they are assisted onto their masks, there will be complete amnesia, with no recollection at all of the event. The good news, if there is any, is that it would be a gentle way to die... but please don't try to prove it the hard way.

The takeaway is that you might SEEM to be OK to a buddy, IE: you might still be finning along the wreck... LONG after you have lost your ability to self rescue. That gag strap BOV combination is the ONLY way to really get a quick recovery assistance from a buddy while protecting the airway.

Pic was taken on a course that I wrangled for a bunch of civilian pilots as a demonstration, that's me grinning stupidly at front right, 25,000 feet after about two minutes. Feels like a good Margarita buzz at that time. The guys standing in the back are the tenders, it looks like the door is open, but that's the door into the transfer lock.

This type of training is invaluable. We also did it with ROBS (reduced oxygen breathing system) flying a simulator while the trainers slowly reduce the fraction of 02 in the mix you are breathing. I taught that course for almost 10 years... it was VERY interesting work. I now do it as part of advanced rebreather training, with a self made ROBS system here in the Little Diveshop of Horrors. If anyone wants a demo, feel free to come by.



Dave

.
Click to expand...

I appreciate this link has been previously posted, but for anyone in doubt about our ability to fully comprehend the danger we are in during a hypoxic event, watch this link which clearly demonstrates what has been articulated by Dave:

Portillo Seconds From Death - Horizon:How to Kill a Human... - YouTube

Remember this 'experiemnt' is in comfortable, warm controlled conditions, the subject was pre-warned of the event and is at complete rest and not struggling with the issues of increased gas density and its effect on efficient ventilation.

Rgds Paul
 
Paul Haynes said:
I appreciate this link has been previously posted, but for anyone in doubt about our ability to fully comprehend the danger we are in during a hypoxic event, watch this link which clearly demonstrates what has been articulated by Dave:

Portillo Seconds From Death - Horizon:How to Kill a Human... - YouTube

Remember this 'experiemnt' is in comfortable, warm controlled conditions, the subject was pre-warned of the event and is at complete rest and not struggling with the issues of increased gas density and its effect on efficient ventilation.'

Rgds Paul
Click to expand...

...and scientific research has shown CO2 is narcotic and psychedelic (in high concentrations).

So it is not only an O2 issue (Hypoxia and Hyperoxia could be prevented by quality and dependable pPO2 monitors and paying proper attention to them), but also a CO2 issue in which a BOV with Crown Strap could be of help (and there are often no dependable CO2 Monitors made available in rebreathers to mitigate the risk).

In a recent case (land based incident),

"Dr Calder said carbon dioxide can cause ‘havoc with the chemistry of the body’ as it leaves the victim confused and unable to act.

The results, known as hypocapnia [probable print error], would include headaches, then confusion and eventually unconsciousness and cardiac arrest, the inquest heard.

Speaking about carbon dioxide poisoning, he added: ‘There may have been a period of awareness but it may have been short and rapidly contradicted by his decreasing ability to escape.’

Asked about how he may have died in the bag, Dr Shepherd said a struggle for fresh air would have been a ‘strong driver’ for an attempt to escape.
But he added: ‘There would have been a time when he was aware, it is possible. But carbon dioxide poisoning can cause confusion very quickly.’

Read more: Gareth Williams inquest: DNA from 2 people found on bag holding body of MI6 spy | Mail Online
 
I think we're still going through the growing pains of CCR diving. There's no doubt that some of the technologies we debate now will one day be standard operating procedure. Basically every safety idea we hold as a no brainer was at one point debated with both sides being considered. Seat belts aren't necessary, pressure gauges are silly, BCD's are too, long hoses are a hassle, helium is stupid when we have air, nitrox is voodoo. It will be interesting to see where this debate is in 10 or 15 years. Me thinks BOV's, at the least, will be SOP and gag straps may be as well.
 
Dave Sutton said:
snip...lots of really good info...

.
Click to expand...
Yep, been there, done that in my day time job too Dave. It is rather amusing watching military aircrew 'drunk' with hypoxia (myself included) but then the seriousness bangs in. If you pass that point of 'useful consciousness' then you are screwed.

Another point, which I think I made elsewhere, the colour and visual acuity drops as you enter hypoxic situations so you might not be able to read the displays telling you something is wrong. This is especially the case in dark environments. For night free fall, the aircrew all had to be on O2 above 8000ft, but for day time drops, the regulations were 12000ft.

I like the training Dave to expose divers to hypoxic situations.

Regards
 
I think that the "Portillo" YouTube footage should be compulsory viewing for all MOD1 and beyond courses as it really demonstrates how "comfortably numb" we can become due to hypoxia. If Portillo can't replace an O2 mask when being told that he will die if he doesn't, what chance do you think any CCR diver will have on making the conscious decision, let alone the effort to make the switch to bailout?

Easy answer, absolutely fookin none!!!

Gar
 
Dave Sutton said:
I'd second Paul, and state in addition that the combination of a gag strap and a BOV makes for an easy prospect of training open circuit divers how to respond to an unconcious RB diver... protect the airway and twist the knob.

As far as hypoxia is concerned: I've probably gotten more experience watching others go thru the evolution of incipient hypoxia thru total loss of conciousness while participating in high altitude chamber training at "the day job" than anyone else around. At 25,000 feet pressure altitude in the hypobaric (altitude) chamber, it typically takes about 3-4 minutes to become unconcious after removal of 02 mask.



.
Click to expand...

What ppO2 is it at 25000 feet?
 
The AP Headstrap - are they o-rings at the end of the straps or something more solid, just musing whether i can fit one to the Sentinel.
 
Dave1w said:
I wonder if AP would share information on how many straps have been ordered in the last week. I know I have one on the way....
Click to expand...
I was mulling over getting one and after reading this thread mine arrives from AP tomorrow with my lid and the mended wire.
 
Soggyfox said:
The AP Headstrap - are they o-rings at the end of the straps or something more solid, just musing whether i can fit one to the Sentinel.
Click to expand...

I bought one (because of this thread).

It will fit the Sentinel loop. How comfortable it is in use remains to be seen. Feels 'snug' to me.

:)
 
Case for hard hats

Hi,

as a johnny come lately to this thread, just noted it seems to concern a solo diver who took a DPV into a cave without wearing a helmet. Respectfully suggest, in this accident, prevention would have been better than cure. When diving under your own steam it is hard to get up enough speed to knock yourself unconscious, but with a DPV you certainly can. I remember riding pillion on a DPV in the Devils Ear system and hitting the roof with a tremendous thud, fortunately I have a thick skull.... Buddy looks expectantly at me for signs of consciousness or lack of it.. Took me back to the incident in school when I was leaping across the desks during lunchbreak, not realising that one of them had lost the three screws that fasten the desktop to the legs. Landed on the edge of it and CRASH!!! It flips over and hits me on the same hard skull. Again, my friend looked at me expectantly for signs of brain damage, but once again I got away with it (at least, no more bonkers than the average maths professor).
If diving with a DPV - especially solo - wear a hard hat.
Even without the DPV, at least one life has been saved in British caves by wearing a hard hat. He went down a vertical tube, not realising there was hanging death above. A huge number of rocks and stones fell on him, pinning him helpless, half stunned and unable to move. Then seconds later they slipped again, going further down the tube and so freeing him. Exercise to reader: sketch likely outcome if he hadn't been wearing a hard hat.
Going in cave = pretty good case for a hard hat.
Going in cave with DPV = even stronger case!
Mouthpiece straps remain a good idea tho'.

God Bless,

Dive safe,

Charles.
 
solocavediver said:
Hi,

as a johnny come lately to this thread, just noted it seems to concern a solo diver who took a DPV into a cave without wearing a helmet. Respectfully suggest, in this accident, prevention would have been better than cure. When diving under your own steam it is hard to get up enough speed to knock yourself unconscious, but with a DPV you certainly can. I remember riding pillion on a DPV in the Devils Ear system and hitting the roof with a tremendous thud, fortunately I have a thick skull.... Buddy looks expectantly at me for signs of consciousness or lack of it.. Took me back to the incident in school when I was leaping across the desks during lunchbreak, not realising that one of them had lost the three screws that fasten the desktop to the legs. Landed on the edge of it and CRASH!!! It flips over and hits me on the same hard skull. Again, my friend looked at me expectantly for signs of brain damage, but once again I got away with it (at least, no more bonkers than the average maths professor).
If diving with a DPV - especially solo - wear a hard hat.
Even without the DPV, at least one life has been saved in British caves by wearing a hard hat. He went down a vertical tube, not realising there was hanging death above. A huge number of rocks and stones fell on him, pinning him helpless, half stunned and unable to move. Then seconds later they slipped again, going further down the tube and so freeing him. Exercise to reader: sketch likely outcome if he hadn't been wearing a hard hat.
Going in cave = pretty good case for a hard hat.
Going in cave with DPV = even stronger case!
Mouthpiece straps remain a good idea tho'.

God Bless,

Dive safe,

Charles.
Click to expand...

+1 ...and you can put your several torches on it (I have 6, but 4 would be plenty enough).

P.S. Off topic, ...if you get rid of the buddy and configure for "solo" diving you have cut in half all your failure points and reduced by 50% the chance of human error :crossfing .

IMG_20120226_175755.jpg
 
Is that concrete your helmet's on or are you underneath it, peering through the grey muddy murk???? (yup, I usually put lights on my helmet, though Florida divers used to hand held lights complain about being blinded when I look towards them.)

Cheers,

Charles.
 
solocavediver said:
Is that concrete your helmet's on or are you underneath it, peering through the grey muddy murk???? (yup, I usually put lights on my helmet, though Florida divers used to hand held lights complain about being blinded when I look towards them.)

Cheers,

Charles.
Click to expand...

I am literally under the helmet... they sent me a size too big for my head :lol: .

I love blinding fellow divers, especially the DIR with their crew of Sherpas... they look at me in disgust and leave the cave (much safer diving)!

...these DIR Florida canister umbilical torches are fashionable... but a bit like putting all your eggs in one basket and I find my third hand is always busy doing something else.

P.S. Sorry Clare, I am S t r o k e!
 
Last edited:
gianaameri said:
enough).

P.S. Off topic, ...if you get rid of the buddy and configure for "solo" diving you have cut in half all your failure points and reduced by 50% the chance of human error :crossfing .
Click to expand...


Or as I've said many times before:

"The safest way to dive solo is to refuse to dive with an idiot"



Off to Prague for 10 days, behave while I'm gone!

Enjoy.


Dave


.
 
You must log in or register to reply here.
Back
Top