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Thread: Getting relevant responses to inquiries

  1. #11
    RBW Member topper133 is an unknown quantity at this point topper133's Avatar
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    Re: Getting relevant responses to inquiries

    Quote Originally Posted by heyydude  View Original Post
    I converted to straight Heliox in 1996 and never looked back. Some guys, like Rich Pyle tell me they get the "heebie-jeebies" past 300 ft on Helox, so he uses mix, but in the scenario you list, I would run 15/85 - I was never a fan of having hypoxic mixes
    I assume you're talking about your Deep BO here with 15/85 and not your dil running at 1.65! ;-p

  2. #12
    Dave Tomblin wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc's Avatar
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    Re: Getting relevant responses to inquiries

    Quote Originally Posted by bobbob23  View Original Post
    Thank you so much for taking the time to contribute was not expecting someone as prominent in the industry as you to help out. You'd have to admit that the average user here is not ever going to be in the same position as you in terms of legalities. My feeling is that would someone be wary of my op why wouldn't they simply ignore it rather than make accusations. Again I couldn't even imagine doing any dive like this. This was the kind of feedback I was hoping to get and it if anything makes me want to learn even more. Again thank you. If you have any recommended reading please let me know.
    I will disagree with Kevin (as clever as he is) on a couple of points:

    I would never connect my BOV to diluent if I was carrying the traditional 2l - 3l supply. At 100m that will be about 2 minutes before you have to find another gas.

    I am not a fan of auto setpoint switches. For fast descents I stay on low (0.4 is my choice too) until I reach bottom then switch. Usually I am spiking past 1.6 and have to slow my descent rate anyway. It takes a long time to breath down a hyperoxic loop at 200+ ft.
    Cheers,

    Dave....

    www.wedivebc.com

  3. #13
    RBW Member beldridg is an unknown quantity at this point beldridg's Avatar
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    Re: Getting relevant responses to inquiries

    Quote Originally Posted by wedivebc  View Original Post
    I am not a fan of auto setpoint switches. For fast descents I stay on low (0.4 is my choice too) until I reach bottom then switch. Usually I am spiking past 1.6 and have to slow my descent rate anyway. It takes a long time to breath down a hyperoxic loop at 200+ ft.
    With all respects to Kevin, I have to agree with this.

    There are a few cases whereby if my high setpoint goes on automatically at a "shallow-ish" depth then my PO2 can just skyrocket on the "real" descent.

    Admittedly, I did forget to switch at depth once (maybe twice) early in my CCR diving, but each time I noticed it when my NDL went up quickly and I immediately switched it.

    Also, if I know I'm going to be slow in going down for whatever reason or if I'm going to have an intermediate stop, I can always manually add some O2 if I want to increase my PO2 past the low setpoint.

    I also don't use an auto switch on ascent.

    Regards,

    - brett

  4. #14
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    Re: Getting relevant responses to inquiries

    Quote Originally Posted by wedivebc  View Original Post
    I will disagree with Kevin (as clever as he is) on a couple of points:

    I would never connect my BOV to diluent if I was carrying the traditional 2l - 3l supply. At 100m that will be about 2 minutes before you have to find another gas.

    I am not a fan of auto setpoint switches. For fast descents I stay on low (0.4 is my choice too) until I reach bottom then switch. Usually I am spiking past 1.6 and have to slow my descent rate anyway. It takes a long time to breath down a hyperoxic loop at 200+ ft.

    What I forgot to mention was that we also had Quick Connects on our OC 2nd Stage hoses, along with long "pigtails" coming off the bailout bottles with matching Quick Connects.

    We were handling lots of gear back then - cameras, lights, spare cameras, etc.

    The general idea being that your OC Bailout was more of a "travel" gas (remember that term?) to get to the real bailout, which we would often stage on the reef where we were shooting. We practiced taking a breath from the 2nd Stage, then disconnecting the QC and hooking it into the QC whip on the larger bottle. We also kept a regular 2nd Stage on that bottle with a long hose just in case.

    We'd also have additional staged bottles on the anchor line (if there was one) or tethered to whatever unfortunate assistant that was working for us at the time. I have a picture someplace of Kent Schnoeker wearing twin 120's + carrying four 80's as possible bailout for the 3 of us that did the penetration dives to the Whale Cave in Fiji at 220'. Poor bastard...

    I should note that techniques and methods have been refined over time, and that I have no disagreement with the others on here who are instructors/trainers. Our situations were rather unique, as was our gear, so we did what we did - and also back then 1.6 was no biggie - we would just metabolize it down, as it made the hair on our chests grow faster.

    If you want to hear about some extreme Oxygen, ask Rich Pyle about his 5.0 ppO2 descent. That is one for the record books.


    Kevin.

  5. #15
    RBW Member ccfish is an unknown quantity at this point ccfish's Avatar
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    Re: Getting relevant responses to inquiries

    Quote Originally Posted by beldridg  View Original Post
    With all respects to Kevin, I have to agree with this.

    There are a few cases whereby if my high setpoint goes on automatically at a "shallow-ish" depth then my PO2 can just skyrocket on the "real" descent.

    Admittedly, I did forget to switch at depth once (maybe twice) early in my CCR diving, but each time I noticed it when my NDL went up quickly and I immediately switched it.

    Also, if I know I'm going to be slow in going down for whatever reason or if I'm going to have an intermediate stop, I can always manually add some O2 if I want to increase my PO2 past the low setpoint.

    I also don't use an auto switch on ascent.

    Regards,

    - brett

    I`m a friend of automatic setpoint switching - if anyone is interested.. )
    - especially in high current scenery when I have to jump from a boat to greater depth quickly at high descent rate. Main- and backup-computer switch simultaiously that way and I don`t need to swith buttons at two computers at depth - configuration of the switching threshold is tricky though - it depends on diluent PO2 and descent rate - PO2 overshoot is possible ... )

    Cheers Helge

  6. #16
    Dave Tomblin wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc's Avatar
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    Re: Getting relevant responses to inquiries

    Quote Originally Posted by ccfish  View Original Post
    I`m a friend of automatic setpoint switching - if anyone is interested.. )
    - especially in high current scenery when I have to jump from a boat to greater depth quickly at high descent rate. Main- and backup-computer switch simultaiously that way and I don`t need to swith buttons at two computers at depth - configuration of the switching threshold is tricky though - it depends on diluent PO2 and descent rate - PO2 overshoot is possible ... )

    Cheers Helge
    So you like to have your solenoid firing on the way down? How deep before your PO2 spikes beyond a safe level? I find the climb of PO2 is the thing most likely to stop my descent rate and that is why I leave SP low until I hit the target depth.
    Cheers,

    Dave....

    www.wedivebc.com

  7. #17
    RBW Member ccfish is an unknown quantity at this point ccfish's Avatar
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    Re: Getting relevant responses to inquiries

    Quote Originally Posted by wedivebc  View Original Post
    So you like to have your solenoid firing on the way down? How deep before your PO2 spikes beyond a safe level? I find the climb of PO2 is the thing most likely to stop my descent rate and that is why I leave SP low until I hit the target depth.
    yes, solenoid is in firing mode, but would not fire because of considerable amount of hypoxic diluent going to the loop while descending (usually I dive SP_high 1.2 at depth). E.g. with a 10/70 bottom depth 100m and descent of approx 16 to 20 m/min I switch at 70meters depth that way. For shallower dives around 50m with 18/45 I actually have set my switching point at 27meters - as I said before estimating the right switching depth is tricky - depending on many individual parameters. In effect my po2 as seen in my diving-log is approximating SP_high while descending to say 40 meters - than stays constant down to bottom.
    I feel comfortable with this method but of course have a very close eye on the PO2-display while descending - very seldomly I have to correct PO2 manually by flushing diluent or experiencing too much PO2-oversoot

    Cheers Helge
    Last edited by ccfish; 28th July 2018 at 09:06.

  8. #18
    RBW Member beldridg is an unknown quantity at this point beldridg's Avatar
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    Re: Getting relevant responses to inquiries

    Quote Originally Posted by ccfish  View Original Post
    I`m a friend of automatic setpoint switching - if anyone is interested.. )
    - especially in high current scenery when I have to jump from a boat to greater depth quickly at high descent rate. Main- and backup-computer switch simultaiously that way and I don`t need to swith buttons at two computers at depth - configuration of the switching threshold is tricky though - it depends on diluent PO2 and descent rate - PO2 overshoot is possible ... )

    Cheers Helge
    My backup computer (NERD2) is hard-wired to two cells so I only need to switch my Petrel controller which takes almost no time and I've done it plenty of times in high current holding onto an anchor line on a wreck, etc.

    I understand your point about "custom setting" a depth to trigger the high SP and the need to set two computers if one of them has an internal SP (I'm assuming that is the case here).

    I personally just really like the flexibility to change my set point when I want to change it based upon conditions, descent rates, etc.


    - brett

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