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Nitrox benefits for Cozumel diving

Discussion in 'Cozumel' started by tracydr, Jul 23, 2013.

  1. Darol

    Darol ScubaBoard Supporter ScubaBoard Supporter

    When I get older I'm going to give it a try. We call it "Geezer Gas" and get a kick out of
    those that need it..... :rofl3::rofl3::rofl3:
    tracydr likes this.
  2. boulderjohn

    boulderjohn Technical Instructor ScubaBoard Supporter

    # of Dives: 1,000 - 2,499
    Location: Boulder, CO
    The danger of exceeding MOD is not only a function of depth, it is a function of time. To begin with, MODs are made pretty conservative to be on the safe side. The depth of your hypothetical rescue is only 20 feet below the contingency MOD advocated by most agencies, and it is within the old MOD used by some in the early days of nitrox. If you can effect a rescue in a reasonable amount of time, going to 150 feet on EANx 32 should not be a problem, and I would not hesitate to do it.

    Of course, in all cases you are playing the odds--nothing is certain. Staying within standard MODs, the odds are overwhelmingly on your side for staying safe. As you exceed MODs for increasing amounts of time, the odds start to turn against you, but it isn't like you suddenly die the minute you go 5 feet below the MOD.
    Pelagicsal, cvchief, tracydr and 4 others like this.
  3. Lorenzoid

    Lorenzoid ScubaBoard Supporter Staff Member ScubaBoard Supporter

    # of Dives: I just don't log dives
    Location: Atlanta, USA
    Do you really think this will be the last SB thread to argue over this question? I thought it was a good thread because it's the first time I really gave any thought to the advice about diving nitrox using air tables/computer. I have never done it, and I am not persuaded that it's likely to benefit me.

    Nitrox is not free in many places, and the cost of nitrox for a week at a resort or liveaboard for my wife and me is something we factor into our decision of where to book. Sometimes we opt for nitrox, and sometimes we don't.
  4. AggieDiver

    AggieDiver Contributor

    # of Dives: 200 - 499
    Location: Houston, Texas
    I have a suggestion...if you think a thread about the benefits (or lack thereof) of nitrox is "beating a dead horse", then don't open the thread...bingo...problem solved! Some of us don't live full time on Scubaboard and might have missed the last 15 threads on any given subject. So for us, we may find value in the thread and in having discussions you might have read before on other threads. If you really feel incapable of not clicking on these threadsa and feel like you have to post something, rather than waste your time posting sarcastic posts about how overdiscussed the topic is, why not do a quick search and post some links to the previous discussions to help out folks who may have missed the earlier threads.
    tracydr, MMM, John Larsen and 2 others like this.
  5. DjDiverDan

    DjDiverDan Regular of the Pub

    # of Dives: 500 - 999
    Location: Sunnyvale, TX USA
    There is one topic that hasn't been addressed at all in this thread, and that is Nitrogen Narcosis. Different people have different levels of tolerance to Nitrogen - some people will have very little effect even at 150 feet (below the limit for recreational diving), while others will begin to get narced at a depth as low as 100-120 feet. It seems that Nitrox, even a mix like EAN 28, which you might want for a deeper dive to 135 feet (ppO2 at 135 feet on EAN 28 would be at about 1.4; still low risk for Oxygen Toxicity with a short exposure time), by reducing PPN, will also reduce the effect of narcosis at any given depth. An alert diver unimpaired by narcosis is a safer diver. One more reason to dive Nitrox.
  6. dfx

    dfx Regular of the Pub

    # of Dives: 200 - 499
    Location: Binbrook, ON
    Define "need". Need for what?
  7. boulderjohn

    boulderjohn Technical Instructor ScubaBoard Supporter

    # of Dives: 1,000 - 2,499
    Location: Boulder, CO
    That is a common belief, but it is not shared by authorities. Nitrogen is not the only gas that has narcotic qualities--they all do. According to the most accepted theory on what causes narcosis, oxygen should be even more narcotic than nitrogen. The problem is that it is hard to calculate because some of the oxygen is metabolized, and it is hard to test the narcotic effects of oxygen because of the threat of toxicity.

    The consensus of all nitrox authorities I know, including the two agencies for which I teach nitrox courses, is that nitrox is just as narcotic as air, and one should not expect to have any less narcosis when using it.
    tracydr, D_B, Lorenzoid and 1 other person like this.
  8. Christi

    Christi PADI MSDT/Dive op owner ScubaBoard Supporter

    # of Dives: 2,500 - 4,999
    Location: Cozumel, MX
    And on some days I get narced at 80 feet other days I don't get narced at 120 or more

    One of the major factors no one seems to be addressing is physiology. There is so much more to DCS (and nitrogen narcosis) than simply depth, length, partial pressure, etc. Each person's physiology an any single given day varies and plays a critical role in how fast/slow your tissues absorb nitrogen and likewise release the nitrogen.

    A diver can do "everything right" - but if your body chemistry/physiology is off keel and does't want to play well with the nitrogen that day or that dive - it doesn't matter what else you do!

    Anyone can take a hit - even if you've got hundreds of dives under your belt. You can do the same profile you've done 100 times without incident and get bent the 101st time with the same profile. It only takes once. Yes, of course there are risks we take in life everyday, and those of us that love to dive are obviously willing to accept the risk of DCS and we take measures to mitigate our chances of this happening - BUT - don't believe for a second that it can't happen to you if you "do everything right."

    Gotta say it - but this is one of my biggest pet peeves to hear from divers of ANY experience level - and ESPECIALLY from experienced divers - unfortunately, I hear it ALL the time and it blows my mind every single time I hear the "rationale" of it. "I don't need DAN because I dive very safe and I have never been bent before, why would it happen now?" UGH - makes me want to scream and yank their c-card away - hahahahaha!

    Don't dive nekkid people! If you can't afford DAN or similar dive specific insurance, then you shouldn't be diving! DCS is not something that you can ignore and it will just go away - without treatment, it WILL NOT go away and will get worse, potentially life changing, debilitating or fatal if not treated!

    In the famous words of some of my favorite hyperbaric Dr.'s - "The only way to be sure you won't get bent is not to dive, or not to come up!"

    If you're on the island tomorrow - I'm going to plug this again! Please join us at the Hyperbaric Chamber on Calle 5 tomorrow night at 7pm for an informative seminar on DCS, barotraumas, other diving safety topics, and a tour of the chamber! EVERYONE can benefit and learn from this - even me :) I went last week, and going again tomorrow! Hope to see you there!
  9. Brules

    Brules Contributor

    # of Dives: 200 - 499
    Location: Oklahoma City
    Agreed. You do/can do so many bounces in Cozumel - I personally think it ups the risk for DCS hits on top of everything else.

    I consider my using nitrox secondary insurance, and am seriously thinking of just doing 32/36 on all tanks.
  10. Christi

    Christi PADI MSDT/Dive op owner ScubaBoard Supporter

    # of Dives: 2,500 - 4,999
    Location: Cozumel, MX
    Nitrox will not keep you from getting bent either! It's NOT insurance! Do not have a false sense of security because you are diving it! Yes, I dive only nitrox, it's a measure I take to mitigate the risk, but I KNOW the risk is still very much there!

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