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Might be a stupid question but.....

Discussion in 'Cave Diving' started by rick00001967, Apr 4, 2021.

  1. rick00001967

    rick00001967 Tech Instructor

    # of Dives: 500 - 999
    Location: canada
    hey all. i am only cavern certified. this question is for information only. i do not dive caves.....EVER.

    during my entry level training we obviously discussed gas planning and the minimum rule of thirds.

    i am wondering if any of you regularly leave a stage bottle along the way as a back up ? i am not talking about extremely long dives where leaving stages may be required, i am asking about a dive where you can easily plan with a set of doubles.

    is this something that would be frowned upon ? would it simply be considered over kill ? or do some do this ?

    i would be interested in the reasoning behind it and under what circumstances you might consider doing this.

    from my point of view only as someone with limited training, i would want to plan any dive as if i was solo (even if i was with a buddy or a team). so my logic (even though it may be flawed) is this.....

    just as an example....if i am using doubles with 3000psi each, i must turn the dive with at least 2000psi in each (in reality the dive should be turned before that). the worst case scenario would be a complete loss of one tank at this point in the dive. that leaves me with one tank having 2000psi which is the amount it took me to get to this point. doesn't sound like a great situation to be in. so why not leave a stage at a point in the cave when you reach 2500psi in each tank (half way in) ?

    i understand many might say this is unnecessary as you would have at least one buddy with extra gas. but from the standpoint of planning AS IF you were solo and being self reliant, is this something anyone would do ?
    it does not seem to be much of a hassle to do this. but the upside certainly seems substantial. so why not do it ?

    i am sure others will have a much different perspective and i would love to hear the rational either for or against this.

  2. _Ralph

    _Ralph Contributor

    1/3rds in cavern now?

    Paul M, arthurng311 and grantctobin like this.
  3. Tribal

    Tribal Contributor

    # of Dives: 200 - 499
    Location: Belgium
    If you don’t feel comfortable diving on 3rds then do 4ths? If that’s not enough gas go full cave and take stages to drop :)
  4. lermontov

    lermontov Contributor

    # of Dives: 500 - 999
    Location: christchurch
    if you see the training as a continuum then the sooner you integrate reserves in to divers thinking the better so i cant see it hurting
    Dan G likes this.
  5. lermontov

    lermontov Contributor

    # of Dives: 500 - 999
    Location: christchurch
    i do a lot of wreck penetration dives and stage bottles simply because a) the areas are too tight and too many hazards to take lots of gear b) your basically on your own in some areas as a buddy can add to the problems and often unlikely to be able to help you
    rick00001967 likes this.
  6. helodriver87

    helodriver87 DIR Practitioner

    # of Dives: 500 - 999
    Location: New Mexico
    It's situational. Not normally though. The usual answer is dive more conservatively than thirds if you're worried about it being too aggressive. I will drop a safety on the exit side of particularly nasty restrictions or difficult sections of cave if I feel like it might be necessary or if it allows me more time to negotiate more technically challenging passage.
    rick00001967 and grantctobin like this.
  7. Cdncoldwater

    Cdncoldwater Contributor

    # of Dives: 100 - 199
    Location: Atlantic Canada
    I was taught 1/3s on my OW course and it has been the standard for every course I've done with my LDS. We covered the standard planning taught in PADI for the theory but it was also taught that in the areas we dive and for safety plan with the 1/3 method. They also charge by cf not tank on fills so they walk the walk as far as supporting the gas planning method they teach. The only time I haven't done 1/3 is when I did a dive trip and it was different to go below 1/3 the first few dives; had to reset my thinking and at home I simply dive 1/3s as a rec diver.
  8. Wstern5

    Wstern5 Contributor

    # of Dives: 200 - 499
    Location: Brooklyn
    Thirds isn’t really conservative enough for two person teams, especially in a low flow cave. I’ve heard of solo divers taking a stage they do not plan to use, commonly referred to as a “buddy bottle”. Most people wouldn’t bring a “just in case stage” unless there were some other special circumstances involved.
  9. PfcAJ

    PfcAJ Contributor

    # of Dives: 5,000 - ∞
    Location: St Petersburg, Fl
    So with this line of thinking, you're considering two major and unrecoverable failures. You lost a tank (easier in SM, tougher in manifolded doubles), AND you lost your buddy. And (of course) it all happened at max penetration.

    I mean, is there anything *wrong* with dropping a safety? Other than needlessly complicating your plan, no. But I'd consider revisiting the assumptions that got you to the point of needing it, and work on those. That's the foundation that's fractured in this case.

    Big long complicated dives? Sure. Safeties. All day. A regular thing? Nah, not needed if you've got a good base.
    Paul M, KevinNM and grantctobin like this.
  10. p_kos

    p_kos Contributor

    # of Dives: 200 - 499
    Location: Ontario
    I was taught to drop one Al80 of EAN32 (typical back gas in Florida) per team about 400’ into a cave when diving in a team of 3 within NDL limits and using the rule of 3rds as part of NAUI Cave 1. Just as a backup if things really go pear-shaped and given that statistically most drown within about 400’ or less of a cave’s exit point. Overkill? Perhaps, but not much of an inconvenience so worth it in my opinion. Gets you practice dropping/picking up stages if nothing else, good perpetration for Cave 2 where stage dropping becomes a necessity.
    OTF and rick00001967 like this.

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