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Thread: Another Co2 story... and pondering a BOV.

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    Shearwater Copis Diver Gill Envy has a reputation beyond repute Gill Envy has a reputation beyond repute Gill Envy has a reputation beyond repute Gill Envy has a reputation beyond repute Gill Envy has a reputation beyond repute Gill Envy has a reputation beyond repute Gill Envy has a reputation beyond repute Gill Envy has a reputation beyond repute Gill Envy has a reputation beyond repute Gill Envy has a reputation beyond repute Gill Envy has a reputation beyond repute Gill Envy's Avatar
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    Another Co2 story... and pondering a BOV.

    Months back I nearly watched my wife expire before my eyes. She doesn't like telling this story to strangers, but I think it's valuable so i've taken some liberty here. we were in Indonesia on an island archipelago called Alor, known for whipping currents and big fish frenzies. Tempted by stories of feeding pelagics, we crawled our way down to 130 ft, out on a point while the current was running strong and suddenly the current went from iffy to overwhelming as a gust of confused current threatened to take us switfly down and away from the wall. My wife chose to hold on with both hands trying to figure out where to find shelter, she should have let go and drifted and swam along the wall but could not see anything but flat exposed areas...she wasn't sure what to do. then a blast of current beared down on her so strong it ripped her DSV right out, out went the gas from the loop, into the loop went some salt water, back in the mouth went the DSV on bottomed out C-lungs, current so strong the CL's were collapsed and wouldn't hold anything and the schrader style ADV just was not keeping up with her inhales.

    She did what so many folks do when chased into their reptilian brain stem; she Froze and hyperventilated, cornered in the dead end of a mental maze. witnessing this from a distance, I could see that she was in distress so I opted to pull my way back along the rocks into the full brunt of current to get beside her. I handed her BO reg to her and she refused it, that is when I knew the sh#t was really hitting the fan...already caught in the vicious cycle of rapid, reflexive breathing to the point of not being able to pause to get the BO reg in her mouth... this all happened in a matter of 10 seconds. We went from an iffy current situation to overwhelmed in a snap. I practically pried her fingers away. We had to swim with all our might to avoid going deeper till we drifted to a protected spot out of stongest flow of the current, which was well out of sight of where we had been... feeling out of control as we drifted upped the anti that much more. By the time we got to a spot where we could pause, she was screaming through her DSV: "I can't breathe!, I can't breathe!!" That panicked, wide eyed look is unmistakable, it appeared that she was moments from passing out or bolting to the surface. You could hear a bit of water in her loop getting sucked into her mouth and down into her lungs like she was breathing through a wet straw. It took suprisingly long for her to collect herself and get her breathing back under control and loop back to optimum volume. From what I can tell she basically took a Co2 hit, not from breakthrough but from not being able to off gas the co2 from her blood stream. We both gathered ourselves for a bit before our cautious ascent... all the while, we maintained a surprisingly stable po2.

    this has made me think about a BOV a lot harder since it was obvious that there was nothing she could do to successfully get off the loop once caught in the downward spiral. so why haven't I run out and gotten a BOV? I have to admit that the added profile and drag has it's risk benefit equation and while i'm closer to going for one, i'm not quite convinced it's the right thing for me and i'm also hoping that someone will come out with a better design. Even in the above scenario the current was so strong it would have been free flowing and impractical for such diving. I came to the conclusion a while back that one should BO long before they think they need to and now I realize that in some rare cases there is no warning, as Dave S so well illustrated in his post. I understand and choose to take this risk for now, but that may just be a matter of time. If there was one with a very low profile that pressurized as it was switched on so it didn't free flow in current but also did not require turning on a flow stop in addition to switching on, I would be more likely to add it to the wish list, as I more graphically see it's value. For now, it's just one more area where I pad the equation that much more and do my best to avoid getting in such a situation in the first place.

    hope this is helpful to someone, dive safe!
    g

    Gill Envy

  2. #2
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    Re: Another Co2 story... and pondering a BOV.

    Quote Originally Posted by Gill Envy  View Original Post
    Months back I nearly watched my wife expire before my eyes. She doesn't like telling this story to strangers, but I think it's valuable so i've taken some liberty here. we were in Indonesia on an island archipelago called Alor, known for whipping currents and big fish frenzies. Tempted by stories of feeding pelagics, we crawled our way down to 130 ft, out on a point while the current was running strong and suddenly the current went from iffy to overwhelming as a gust of confused current threatened to take us switfly down and away from the wall. My wife chose to hold on with both hands trying to figure out where to find shelter, she should have let go and drifted and swam along the wall but could not see anything but flat exposed areas...she wasn't sure what to do. then a blast of current beared down on her so strong it ripped her DSV right out, out went the gas from the loop, into the loop went some salt water, back in the mouth went the DSV on bottomed out C-lungs, current so strong the CL's were collapsed and wouldn't hold anything and the schrader style ADV just was not keeping up with her inhales.

    She did what so many folks do when chased into their reptilian brain stem; she Froze and hyperventilated, cornered in the dead end of a mental maze. witnessing this from a distance, I could see that she was in distress so I opted to pull my way back along the rocks into the full brunt of current to get beside her. I handed her BO reg to her and she refused it, that is when I knew the sh#t was really hitting the fan...already caught in the vicious cycle of rapid, reflexive breathing to the point of not being able to pause to get the BO reg in her mouth... this all happened in a matter of 10 seconds. We went from an iffy current situation to overwhelmed in a snap. I practically pried her fingers away. We had to swim with all our might to avoid going deeper till we drifted to a protected spot out of stongest flow of the current, which was well out of sight of where we had been... feeling out of control as we drifted upped the anti that much more. By the time we got to a spot where we could pause, she was screaming through her DSV: "I can't breathe!, I can't breathe!!" That panicked, wide eyed look is unmistakable, it appeared that she was moments from passing out or bolting to the surface. You could hear a bit of water in her loop getting sucked into her mouth and down into her lungs like she was breathing through a wet straw. It took suprisingly long for her to collect herself and get her breathing back under control and loop back to optimum volume. From what I can tell she basically took a Co2 hit, not from breakthrough but from not being able to off gas the co2 from her blood stream. We both gathered ourselves for a bit before our cautious ascent... all the while, we maintained a surprisingly stable po2.

    this has made me think about a BOV a lot harder since it was obvious that there was nothing she could do to successfully get off the loop once caught in the downward spiral. so why haven't I run out and gotten a BOV? I have to admit that the added profile and drag has it's risk benefit equation and while i'm closer to going for one, i'm not quite convinced it's the right thing for me and i'm also hoping that someone will come out with a better design. Even in the above scenario the current was so strong it would have been free flowing and impractical for such diving. I came to the conclusion a while back that one should BO long before they think they need to and now I realize that in some rare cases there is no warning, as Dave S so well illustrated in his post. I understand and choose to take this risk for now, but that may just be a matter of time. If there was one with a very low profile that pressurized as it was switched on so it didn't free flow in current but also did not require turning on a flow stop in addition to switching on, I would be more likely to add it to the wish list, as I more graphically see it's value. For now, it's just one more area where I pad the equation that much more and do my best to avoid getting in such a situation in the first place.

    hope this is helpful to someone, dive safe!
    g
    Gil; was simply letting go not an option....? Was this a shore dive...? A boat based drift...? Were you expected to return to an upline...?
    I'll admit, I have limited experience in wall dives, even less with unpredictible currents, or complex currents on walls. I vaguely recall stories of rip type currents forming on walls and pulling people down faster than inflators could respond, and the reaction was to swim parallel or out, its been a while; I've forgotten...

    If the currents pulled the DSV, they would pull a BOV. Mem let me take his scooter for a spin the other day, the drag on the DSV was way noticable if in any position other than head-on, so I'd have to imagine comperable or worse in a strong current situation like you describe. Out of habit, I don't count on the shrader to bottom out in my ADV, I throw my hand under it and fire it manually if I want some....

    Thanks for sharing...

    -Tim

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    Re: Another Co2 story... and pondering a BOV.

    Quote Originally Posted by Gill Envy  View Original Post
    Even in the above scenario the current was so strong it would have been free flowing and impractical for such diving.
    That is a typical case of CO2 retention and could have ended badly. Those currents can be crazy. I considered myself an experienced current diver until we dove in Indonesia. Those currents are a different category! Did you have reefhooks with you? These should be mandatory on those dives.

    To BOV or not to BOV ... I used a Poseidon regulator on a divematics BOV and it worked well in extreme currents down to 65 meters in Indonesia - Komodo. Go for it. I would recommend the Golem BOV or wait for the new APD one (if you are still diving your Evo's).

    Peter

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    Re: Another Co2 story... and pondering a BOV.

    Hi Gill,

    Wow that is scary experience, thanks for sharing and I am glad that you guys are OK.

    Cheers,


    BB

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    Re: Another Co2 story... and pondering a BOV.

    Quote Originally Posted by Gill Envy  View Original Post
    Months back I nearly watched my wife expire before my eyes. She doesn't like telling this story to strangers, but I think it's valuable so i've taken some liberty here. we were in Indonesia on an island archipelago called Alor, known for whipping currents and big fish frenzies. Tempted by stories of feeding pelagics, we crawled our way down to 130 ft, out on a point while the current was running strong and suddenly the current went from iffy to overwhelming as a gust of confused current threatened to take us switfly down and away from the wall. My wife chose to hold on with both hands trying to figure out where to find shelter, she should have let go and drifted and swam along the wall but could not see anything but flat exposed areas...she wasn't sure what to do. then a blast of current beared down on her so strong it ripped her DSV right out, out went the gas from the loop, into the loop went some salt water, back in the mouth went the DSV on bottomed out C-lungs, current so strong the CL's were collapsed and wouldn't hold anything and the schrader style ADV just was not keeping up with her inhales.

    She did what so many folks do when chased into their reptilian brain stem; she Froze and hyperventilated, cornered in the dead end of a mental maze. witnessing this from a distance, I could see that she was in distress so I opted to pull my way back along the rocks into the full brunt of current to get beside her. I handed her BO reg to her and she refused it, that is when I knew the sh#t was really hitting the fan...already caught in the vicious cycle of rapid, reflexive breathing to the point of not being able to pause to get the BO reg in her mouth... this all happened in a matter of 10 seconds. We went from an iffy current situation to overwhelmed in a snap. I practically pried her fingers away. We had to swim with all our might to avoid going deeper till we drifted to a protected spot out of stongest flow of the current, which was well out of sight of where we had been... feeling out of control as we drifted upped the anti that much more. By the time we got to a spot where we could pause, she was screaming through her DSV: "I can't breathe!, I can't breathe!!" That panicked, wide eyed look is unmistakable, it appeared that she was moments from passing out or bolting to the surface. You could hear a bit of water in her loop getting sucked into her mouth and down into her lungs like she was breathing through a wet straw. It took suprisingly long for her to collect herself and get her breathing back under control and loop back to optimum volume. From what I can tell she basically took a Co2 hit, not from breakthrough but from not being able to off gas the co2 from her blood stream. We both gathered ourselves for a bit before our cautious ascent... all the while, we maintained a surprisingly stable po2.

    this has made me think about a BOV a lot harder since it was obvious that there was nothing she could do to successfully get off the loop once caught in the downward spiral. so why haven't I run out and gotten a BOV? I have to admit that the added profile and drag has it's risk benefit equation and while i'm closer to going for one, i'm not quite convinced it's the right thing for me and i'm also hoping that someone will come out with a better design. Even in the above scenario the current was so strong it would have been free flowing and impractical for such diving. I came to the conclusion a while back that one should BO long before they think they need to and now I realize that in some rare cases there is no warning, as Dave S so well illustrated in his post. I understand and choose to take this risk for now, but that may just be a matter of time. If there was one with a very low profile that pressurized as it was switched on so it didn't free flow in current but also did not require turning on a flow stop in addition to switching on, I would be more likely to add it to the wish list, as I more graphically see it's value. For now, it's just one more area where I pad the equation that much more and do my best to avoid getting in such a situation in the first place.

    hope this is helpful to someone, dive safe!
    g
    ew nasty story - so glad it turned out ok.

    I have done a lot of diving around there and I know the currents can be terrible. I wear a nova FFM. Because of this I have zero issues with currents pulling off dsvs there. I have zero issues with jaw fatigue in strong currents and importantly (and I think this is often overlooked) the use of a FFM doesnt make one clench ones teeth down hard against the mouthbite to hold dsv in place in strong currents (this breathing through teeth biting down on mouthbite can strongly increase wob right when you least want it)

    with the nova (if fitted with side reg) you can purge the side reg yourself to give her gas and create a positive pressure in the mask - this in turn will drastically reduce her percieved wob - which can be all the difference between recovery from co2 retention and death


    You can also just use a dsv strap to help keep it in place. Adding a bov with no strap (or no ffm) would likely make things worse (in these currents)

    thanks for sharing.

    Bottom line - in these very strong currents i think its wise to use a dsv strap or better still a ffm
    Last edited by Drmike; 8th July 2008 at 07:41.

  6. #6
    Shearwater Copis Diver Gill Envy has a reputation beyond repute Gill Envy has a reputation beyond repute Gill Envy has a reputation beyond repute Gill Envy has a reputation beyond repute Gill Envy has a reputation beyond repute Gill Envy has a reputation beyond repute Gill Envy has a reputation beyond repute Gill Envy has a reputation beyond repute Gill Envy has a reputation beyond repute Gill Envy has a reputation beyond repute Gill Envy has a reputation beyond repute Gill Envy's Avatar
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    Re: Another Co2 story... and pondering a BOV.

    hey Tim, thanks for posting. This was a live boat drift dive with heavy current flowing around an islet without any of the usual leeward protection from the current. the current wrapped around both sides of the land mass going down and out, converging at depth before creating an underwater water fall. There are a couple of major morals to the story and we pretty much got what we deserved putting ourselves in such a situation but you live and learn, sometimes the hard way. The boat captain had never had Rebreather divers on board and was really doing everything he could to accommodate our appetite for action packed eye popping dives with little understanding of what limits rebreathers truly had. In several cases we were trusting him while he was trusting us to know where to draw the line. the captain was mostly accustom to timing short OC dives to the squarely tidal currents...we were doing two hour dives way beyond the usual window he was accustom to.

    The deterrent that kept my wife from letting go had partly to do with the fact that these islets were basically pillars that came straight up from the deep sea bed, thousands of feet sheer in some places... essentially bottomless pits. Letting go in this stuff was a nerve racking thing at times. I quickly picked up on how the currents where very similar to those found here in parts of the Puget sound where inlets and baylets and islets create funnel like narrows... stuff I've never attempted to dive outside of slack. we specifically dive such places on slack here to avoid these situations but there is something about being in the tropics in a different land with a dive operator who is giving you the nod and a very experienced and current savvy friend rearing to go. it's all to easy to forget that currents are currents and your personal limits are your's and no one else's no matter how clear and warm the water is.

    Another tricky element was that my wife has relied way to much on me to make the call for her. I was doing my best on this trip to get her to fully make her own decisions. the bottom line is that she should have been making more of these calls for herself all along and might very well have turned the dive down or simply not gone as far out or down.

    weather it's as a partner or a dive buddy, it's all to easy to "follow the leader" and have your ass handed to you because you were relying too heavily on someone else's judgment. I've been on both sides of that equation and learned some hard lessons.

    g

    Quote Originally Posted by netmage  View Original Post
    Gil; was simply letting go not an option....? Was this a shore dive...? A boat based drift...? Were you expected to return to an upline...?
    I'll admit, I have limited experience in wall dives, even less with unpredictible currents, or complex currents on walls. I vaguely recall stories of rip type currents forming on walls and pulling people down faster than inflators could respond, and the reaction was to swim parallel or out, its been a while; I've forgotten...

    If the currents pulled the DSV, they would pull a BOV. Mem let me take his scooter for a spin the other day, the drag on the DSV was way noticable if in any position other than head-on, so I'd have to imagine comperable or worse in a strong current situation like you describe. Out of habit, I don't count on the shrader to bottom out in my ADV, I throw my hand under it and fire it manually if I want some....

    Thanks for sharing...

    -Tim
    "Out of habit, I don't count on the shrader to bottom out in my ADV, I throw my hand under it and fire it manually if I want some...."

    me too but that is quite difficult if you are holding on with both hands with all your might! The shrader is so reliable, I love it, but this one situation brings out it's weakness.
    Last edited by Gill Envy; 8th July 2008 at 08:02.

    Gill Envy

  7. #7
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    Re: Another Co2 story... and pondering a BOV.

    thanks Mike, great feedback! how do you keep the current from crushing the counter lungs. I failed to mention that just before this happened I was sitting right next to her when the current first started to gust, I was holding on with both hands and the pressure of the current against my chest emptied the counter lungs out my mask.

    g

    Quote Originally Posted by Drmike  View Original Post
    ew nasty story - so glad it turned out ok.

    I have done a lot of diving around there and I know the currents can be terrible. I wear a nova FFM. Because of this I have zero issues with currents pulling off dsvs there. I have zero issues with jaw fatigue in strong currents and importantly (and I think this is often overlooked) the use of a FFM doesnt make one clench ones teeth down hard against the mouthbite to hold dsv in place in strong currents (this breathing through teeth biting down on mouthbite can strongly increase wob right when you least want it)

    with the nova (if fitted with side reg) you can purge the side reg yourself to give her gas and create a positive pressure in the mask - this in turn will drastically reduce her percieved wob - which can be all the difference between recovery from co2 retention and death


    You can also just use a dsv strap to help keep it in place. Adding a bov with no strap (or no ffm) would likely make things worse (in these currents)

    thanks for sharing.

    Bottom line - in these very strong currents i think its wise to use a dsv strap or better still a ffm

    Gill Envy

  8. #8
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    Re: Another Co2 story... and pondering a BOV.

    Quote Originally Posted by netmage  View Original Post
    If the currents pulled the DSV, they would pull a BOV. Mem let me take his scooter for a spin the other day, the drag on the DSV was way noticable if in any position other than head-on, so I'd have to imagine comperable or worse in a strong current situation like you describe. Out of habit, I don't count on the shrader to bottom out in my ADV, I throw my hand under it and fire it manually if I want some....
    Hello Tim, this has also been my experience with a BOV in a current-lots of drag in most positions. I couldn't get used to it and removed my Divematics BOV from the rig in the middle of a trip. I went from feeling like I had a kitchen faucet hanging out of my mouth, back to not even noticing my DSV, with only the occasional tug of the hoses when moving around in current.

    And yes, manual activation of the ADV when the situation demands. IMHO, the ADV should be right next to the inhale hose for quickest gas delivery. I know that a shrader valve can't flow as much gas as a 2nd stage, but until I can find a BOV that is compact enough and has the least compromise in OC performance and the same or better CC WOB as my DSV, I won't buy another. Anything which adds drag to my profile is too much of a compromise when diving in strong currents. -Andy

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    Re: Another Co2 story... and pondering a BOV.

    Hi Gill,

    That must have been terrifing for her and I am so glad to hear it all turned out for the best.

    I now dive my unit "Exclusively" with a Drager Panorama fitted with a Golem Gear BOV. The mask is strapped very very securely to your face and is almost impossible to rip off or dislodge if properly fitted (5 straps). It utilises a bite mouthpiece for access to the loop and can allow a full mask flood and still allow 100% access to the loop gas.

    The BOV is snapped in place via the primary P'Port and is almost impossible to pull out without first depressing the release button which is also protected. It is oriented so the diaphragm is normally pointing down out of the flow of any oncoming current and even if it were to be subject to current you could drop your head further to protect it and stop a free flow.

    One feature that's not commonly recognised is that in an event you aren't able to bail out yourself, be it for whatever reason, your buddy could reach over and bail you out by twisting the knob for you.

    It may or may not have worked in your instance but from my own experience, I can't see why it wouldn't.

    Something for you to think about.

    Hope your wife has been able to move on from this and get back to enjoying her diving :)

    Regards,

    Lance
    Last edited by Lancer4545; 8th July 2008 at 08:28.

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    Re: Another Co2 story... and pondering a BOV.

    Quote Originally Posted by Drmike  View Original Post
    I have done a lot of diving around there and I know the currents can be terrible. I wear a nova FFM. Because of this I have zero issues with currents pulling off dsvs there. I have zero issues with jaw fatigue in strong currents and importantly (and I think this is often overlooked) the use of a FFM doesnt make one clench ones teeth down hard against the mouthbite to hold dsv in place in strong currents (this breathing through teeth biting down on mouthbite can strongly increase wob right when you least want it)
    Hi Mike, I tried on a the Nova FFM and it felt like it was sticking out a mile in front of me. While I'm sure you're right about the FFM staying in place, it just seems so much bulkier than a DSV and low profile mask. Did you have trouble getting used to the Nova? Does it pull a lot when turning into or away from current, enough say to make hanging on to something with one hand significantly harder?

    Good point about the teeth clenching scenario, never thought about that before. This is another reason I'm glad I have a Mantabite as it keeps the mouth pc. in place with minimal effort and my mouth open wide. But I'm sure the Nova would still be more comfortable. I haven't given up on the idea yet, looking for someone to convince me who actually dives in these kinds of currents.:D

    Quote Originally Posted by Drmike  View Original Post
    with the nova (if fitted with side reg) you can purge the side reg yourself to give her gas and create a positive pressure in the mask - this in turn will drastically reduce her percieved wob - which can be all the difference between recovery from co2 retention and death
    Hadn't thought about the positive pressure making WOB, at least the inhale, easier. Could indeed make a difference in a crisis.

    Quote Originally Posted by Drmike  View Original Post
    You can also just use a dsv strap to help keep it in place. Adding a bov with no strap (or no ffm) would likely make things worse (in these currents) Bottom line - in these very strong currents i think its wise to use a dsv strap or better still a ffm
    I agree about the BOV, without the strap, in my experience it was just too much of a liability in strong currents. And that was in Ambon last year, with much less current on average than in Alor on this trip. I was with GE and his wife on the dive in this post and very glad I didn't have the Divematics BOV on the rig in that kind of current and let go as soon as I started getting pummeled... -Andy
    Last edited by silent running; 8th July 2008 at 08:49.

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