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Nitrox, Skin Bends and Cozumel

Discussion in 'Ask Dr. Decompression' started by ljwillia, Feb 11, 2019.

  1. ljwillia

    ljwillia Barracuda

    # of Dives: 100 - 199
    Location: Richmond, Va.
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    It wasn't DAN's advise. It was the Doc at the Coz hospital. I've also heard it on the board from some of the Doc's here.

    No problem moving the thread. I really wasn't sure where to post :)
     
  2. DandyDon

    DandyDon Old men ought to be explorers ScubaBoard Supporter

    # of Dives: 200 - 499
    Location: One kilometer high on the Texas High Plains
    48,486
    4,278
    113
    I didn't think so. I am not going to argue medicine with the Coz doctors, but DAN is the authority - and they do not give that advise. Ask them.
     
  3. Trailboss123

    Trailboss123 Divemaster ScubaBoard Supporter

    # of Dives: 1,000 - 2,499
    Location: Tacoma, WA & Channel Islands, CA- USA
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    2,071
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    I usually dive the first dive of the day in Cozumel on air, due to the fact that they are deeper dives on walls with the "potential" for down-currents over depths that could exceed Maximum Operating Depth for 32% or 36%. All other dives during the day are on 36%. I dive Nitrox for the added safety factor as I do a lot of dives on dive trips. I have experienced a significant downwelling only once in Cozumel, but it was significant and it was just recently (this past December). We came through a swim-through at Palancar Deep and out on to the wall at 90 feet. Next thing I know, the bubbles I was exhaling from my reg were not ascending- they were staying in front of my mask, clouding my vision and I was descending pretty quickly. I was prepared for such a potential occurrence, but my wife wasn't. She panicked and put the Darth Vader death grip on my right bicep. We were both descending and as much as I would have preferred to swim out and away from the wall and out of the down current, it was obvious that I wasn't going to be able to get my wife to go along with that - even though we had discussed the possibility of downwellings and what to do in the past. Only option in the moment was to try and inflate and hope that I could pull the both of us up and out of it. I only had my left hand to work with due to her grip on my right arm. We got up and out of it, mostly due to the fact that we were both very perfectly weighted and not overweighted, as so many divers are. Back on the boat, I checked my computer to see how far down we got pulled-- it read 130 feet.
     
    drrich2 and ljwillia like this.
  4. DandyDon

    DandyDon Old men ought to be explorers ScubaBoard Supporter

    # of Dives: 200 - 499
    Location: One kilometer high on the Texas High Plains
    48,486
    4,278
    113
    Not DAN recommended.
     
  5. ljwillia

    ljwillia Barracuda

    # of Dives: 100 - 199
    Location: Richmond, Va.
    245
    133
    43
    That situation is exactly what I fear. Glad to hear you and your wife are ok.
     
    Trailboss123 likes this.
  6. Trailboss123

    Trailboss123 Divemaster ScubaBoard Supporter

    # of Dives: 1,000 - 2,499
    Location: Tacoma, WA & Channel Islands, CA- USA
    1,994
    2,071
    113
    DAN doesn't recommend diving with enriched air? Send me that link, please.
     
    muzikbiz22 likes this.
  7. DandyDon

    DandyDon Old men ought to be explorers ScubaBoard Supporter

    # of Dives: 200 - 499
    Location: One kilometer high on the Texas High Plains
    48,486
    4,278
    113
    Not at all what I said. DAN recommends following Nitrox guidelines, but not making out that it’s other than what it is. No studies support your approach.

    Getting bent can be a complex issue not so simply prevented. Your best bet is safe diving practices, slow & easy ascents, avoid up & down dives, safety stops, good health, good night’s rest, letting the captain pull your kit up, “silent safety stops,” extended relaxing after dives, etc. If you want to add buffers, many computers today have that option, or just keep yours in the green. Yellow range diving is all too easy to acquire in Coz.
     
  8. DandyDon

    DandyDon Old men ought to be explorers ScubaBoard Supporter

    # of Dives: 200 - 499
    Location: One kilometer high on the Texas High Plains
    48,486
    4,278
    113
    No editing on phone mode, huh?

    You cannot find a DAN article that suggests safety is increased by diving nitrox on air settings.
     
  9. uncfnp

    uncfnp Solo Diver

    # of Dives: 500 - 999
    Location: North Carolina
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    I am curious why you are so passionate that this advise does not exist? I have had both DAN and Duke Dive Medicine suggest this as an option. I chose instead to buy a new computer with a conservative algorithm but diving nitrox on air settings/tables is a valid conservative option for divers.
     
  10. Trailboss123

    Trailboss123 Divemaster ScubaBoard Supporter

    # of Dives: 1,000 - 2,499
    Location: Tacoma, WA & Channel Islands, CA- USA
    1,994
    2,071
    113
    I never said anything contrary or against diving Nitrox on air settings- At least I don't think I did?

    I believe that can be a good practice, as long as you are aware that you are doing it and know what your MOD really is and are paying attention to your depth and don't exceed it. The context of my post was my experience in Cozumel with downwellings and the danger of exceeding MOD on potentially deep dives while on Nitrox and the reason I dive air on my first dive of the day and then dive 36% thereafter, as I believe it to be prudent and safe to dive enriched air and I also adhere to and advocate all of the safety measures you espoused in your previous post.
    Maybe I did a poor job of articulating. I apologize.

    My response to you was directly related to the fact that you took a snippet quote from my post where I said- "I dive Nitrox for added safety" -- which was meant to say that I believe diving on enriched air/Nitrox is safer than not doing so-- and then you replied to that by saying that "DAN doesn't recommend it" - it confused me and I interpreted it to mean "DAN doesn't recommend diving with enriched air".

    Pretty sure we are in agreement-- maybe some misinterpretations?
     

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