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A Case for Spare Air

Discussion in 'Advanced Scuba Discussions' started by certainmisuse, Mar 28, 2019.

  1. certainmisuse

    certainmisuse Nassau Grouper

    # of Dives: 100 - 199
    Location: Atlanta GA
    146
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    18
    OK folks, thanks for all the responses. I won't lie, this was a bit of an experiment. I will summarize by saying, do what works for you, after all, when soloing, it's ALL on you. And only you know the situations you are putting yourself in, so you should have the best tools, assuming you have done your homework and practiced. Full disclosure, I recently got back into diving after a long break, and as mentioned I plan to do a great deal of shallow, shore diving in the years to come. For now, I'm just spending a lot of time in the pool though, getting used to my new gear and going through scenarios after the break. Going forward with this thread, I'll likely just sit back and enjoy the remaining posts.
     
    markmud likes this.
  2. 2airishuman

    2airishuman Solo Diver

    # of Dives: 100 - 199
    Location: Greater Minnesota
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    Well, it's your dive. I wouldn't and don't.

    As has been posted upthread, there is a limited window of dives where a 3cf reserve is both necessary and sufficient.

    In evaluating the weight and size considerations there are several components to think about. The 3cf spare air is advertised as 2 pounds empty although this does not include the fill adapter.

    There are 6cf cylinders available that weigh 2.7 pounds empty. Adding regs does add weight.

    Some places will rent you a pony cylinder if you ask, usually an AL40.
     
    markmud likes this.
  3. wetb4igetinthewater

    wetb4igetinthewater Instructor, Scuba

    # of Dives: 200 - 499
    Location: Seattle
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    I think you are missing the point, but I’m sure the stick being used for beating the horse is broken by now.
     
  4. doctormike

    doctormike ScubaBoard Supporter Staff Member ScubaBoard Supporter

    # of Dives: 1,000 - 2,499
    Location: New York City
    5,680
    4,632
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    How would anyone know what works for them, unless they had run out of gas for real?
     
  5. markmud

    markmud Self Reliant Diver, On All Dives. ScubaBoard Supporter

    # of Dives: 200 - 499
    Location: South Lebanon, Ohio
    987
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    Hmm,

    So you don't believe that training and practice can alleviate the need to go OOG and test yourself for real?

    Why are we taught CESA in OW then? It won't help unless you have done it for real--right?

    I have done many pony bottle ascents while compounding the task loading by ripping of my mask, losing buoyancy, and deploying my SMB--all on the same pony bottle ascent.

    I did not learn anything in those training cycles?

    Now I know,
    m
     
    Bob DBF likes this.
  6. doctormike

    doctormike ScubaBoard Supporter Staff Member ScubaBoard Supporter

    # of Dives: 1,000 - 2,499
    Location: New York City
    5,680
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    I didn't say that at all.

    You don't know what "works for you" in situation X until you have been in situation X. I was responding to the statement that you should do what works for you.

    Not sure how you got that I was saying that training and practice are useless.
     
    chillyinCanada and markmud like this.
  7. certainmisuse

    certainmisuse Nassau Grouper

    # of Dives: 100 - 199
    Location: Atlanta GA
    146
    15
    18
    Since this was addressed to me, I'll answer. While I agree my last post was written flippantly, I believe we are using the word "work" here differently. My intention with using that word was to convey that what gives one diver confidence in their abilities through equipment choices, planning, etc., to even start a particular dive might be different than what gives another person the same level of confidence. My usage is with respect to the confidence in starting a dive; your's seems to be associated with an actual failure. My answer to your question: Who knows? That's what the accidents and incidents page is for.
     
  8. doctormike

    doctormike ScubaBoard Supporter Staff Member ScubaBoard Supporter

    # of Dives: 1,000 - 2,499
    Location: New York City
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    Right. My point is best illustrated by that famous Mike Tyson quote - "everybody has a plan until they get punched in the mouth".

    Training is crucial. Diving experience is vital. Practice is critical.

    But actual emergency situations are very different from self inflicted drills with planned task loading. People respond very differently. SAC rates skyrocket. Skills are degraded and forgotten.

    That's why people who describe exactly what they will do in an emergency situation, and plan gas reserves to match that plan, may have a problem if they ever are in that situation for real.

    Here's a rebreather example. Many people insist on using a bailout valve instead of standard dive/surface valve, so that they can be on their open circuit backup with the flip of a switch, instead of just closing the DSV and breathing from a backup regulator. Why? It's not very hard for most people diving CCRs to deploy a regulator and breathe from it. Switching regs underwater is something that many CCR divers did on every dive when they were doing OC tech. What's so hard about that?

    Well, I have heard from a VERY experienced CCR diver that during a CO2 hit, he was so panicked that he couldn't bring himself to switch to the regulator that was inches from their mouth. And that's just not something that you can train for.

    Same with alternate gas supplies. If you might need it, bring enough gas. Even if your full Spare Air is enough to get you to the surface, after a few seconds of free flow or accidental purge, that planned gas supply could be gone when you need it. Don't run such tight margins. Don't expect it to be like in training. "Who knows" is right, but you are always going to have a better chance of survival if you stack the deck in your favor...
     
  9. Bob DBF

    Bob DBF Solo Diver

    # of Dives: I just don't log dives
    Location: NorCal
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    I'm not quite an advocate of Spare Air, however I have owned one and used it, although not in an emergency as I try to avoid them. It would have been handy back before I had an SPG, when emergency ascents were more prevelent.

    For practice CESAs it makes it easier than without, which is the reason I tried one, but I found that the regulator was not as robust as the usual second stage, and the particulate, including sand, in the where I dive, compromised it's relialability.

    Somehow the argument seems to be that a 3 cuft cylinder is not a 30 cuft cylinder and therefore not usefull. Overlooked is that 3 cuft is much better than 0 cuft, especially if the diver is not going to use anything larger. Also overlooked, is that one diver's definition of the proper kit is different than another's, and each has to decide what is right for their dive plan.

    My personal argument was, since I was not going to carry anything very large, the Spare Air was unobtrusive. I know how much 3 cuft is, and I was only looking for another breath at the right time. The alternative, when the Spare Air proved unreliable for me, was back to diving without redundancy on rec dives, buddy and solo.

    Decades later I decided to carry a 19 cuft pony on deeper dives as I'm not as young and fit as I once was, the jury is out on smarter. And some will tell me, even now, that my pony is too small for my dives.

    I don't mind the discussions about Spare Air as it gives information on gas planning for decision making. I do think that after one weighs the information and decides on the SA, it is an informed decision and it's time to move on to the uninformed. We're all going to die, and I don't think it's going to be from SA, or some of the other gear choices that the majority of of the ScubaBoard members jump on.



    Bob
     
  10. TMHeimer

    TMHeimer Divemaster

    # of Dives: 500 - 999
    Location: Dartmouth,NS,Canada(Eastern Passage-Atlantic)
    11,705
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    Agree with all. I've mentioned often that I practice CESA with half full lungs. Better than not practicing it. Same with Spare Air I would imagine, as you've tried it. Even checking out how my foldable snorkel would work. Rescue techniques. You can't practice anything by creating a real emergency ( well, I guess you can...). Then even with the practice you still don't know how you'd react in a real situation and hope you never find out. Yes, 3 cuft. has to be better than 0.
     

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