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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
    At the risk of getting beat up here, allow me to make a case where Spare Air or equivalent might make sense. And no, I do not own the unit. Below are the very specific conditions I had in mind whereby it sounds reasonable to me. There may be others (e.g., buddy separation, etc.).

    1. Solo, therefore it will serve as your redundancy (I know this sounds silly, but see #2)
    2. Shallow (< 30' depending on your SAC rate)
    3. In the event of an OOA, you will head to the surface immediately

    Yes, anybody should be able to perform a CESA from at least some shallow depth, and if you are soloing and can't perform a CESA, well, then, I'm concerned. Anyhow, as for me, I would simply prefer to suck on this on the way up than do the CESA and the capacity seems enough (notwithstanding a few SAC calculations), given #2 and #3.

    What say you?

  2. Scott

    Scott Tech Instructor

    # of Dives: 2,500 - 4,999
    Location: Salt Lake City, Utah
    1. A diver conducting solo dives will already know redundancy is a requirement, otherwise they are not solo diving.
    2. Why spend your dollars on a device that has a depth limit ie: shallow Why not purchase one cylinder that will allow you to solo dive or have redundancy to your level of training and potential future growth? Buy a 40cuft and be done with it as an example.
    3. Carrying adequate gas for the dive and monitoring it is a better option.
  3. ReefHound

    ReefHound PADI Pro

    # of Dives: 1,000 - 2,499
    Location: Houston, TX
    It has it's place though the place is smaller than many think, as long as you realize it's more like Spare Breath. Or CESA Assist.

    Sure, a pony bottle is better but there is theory and there is reality, and the reality is the vast majority of divers aren't going to bother to take a pony bottle when they fly somewhere. A Spare Air is small enough to easily pack and can be easily refilled at destination. As with everything in life, the harder something is to do, the less likely you are to do it. The Spare Air with you is better than the pony you left at home.
  4. caruso

    caruso Loggerhead Turtle

    # of Dives: 200 - 499
    Location: Long Island, NY
    I dived solo with a spare air for years then I came to the conclusion that a 19cf and regulator was not only less expensive but also very easy to throw in a carry-on or checked bag and easy to fill either by the Op I'm diving with or a nearby dive shop and truth be told it's rare that whoever fills it even cares if it's out of VIP. Having the equivalent of 25% more air allows me to draw my main tank reserve lower on every dive giving me longer bottom times on every dive.
    Steve_C, Esprise Me, Coztick and 3 others like this.
  5. doctormike

    doctormike ScubaBoard Supporter Staff Member ScubaBoard Supporter

    # of Dives: 1,000 - 2,499
    Location: New York City
    Hey, if you like it for diving shallower than 30', that's pretty much all that matters. You want it because it makes you feel comfortable. I mean, you aren't going to get a good argument for carrying it in that scenario from a dive planning point of view, but that's not really important.

    There are two situations where you would need redundant gas: Catastrophic gas loss (blow LP hose, unstoppable free flow, etc..), and just running out of air because of a lack of situational awareness. For the first scenario, you would probably make it to the surface from 30 feet faster than you could deploy your spare air. For the second, you shouldn't be planning for that, and there are a million threads here to explain why.
  6. Jim Lapenta

    Jim Lapenta Dive Shop

    # of Dives: 500 - 999
    Location: Canonsburg, Pa
    It's good for a few extra breaths when you ditch your helo and have to get out. Otherwise, waste of money. A 13 or 19 cu ft bottle and basic piston reg is more reliable and cheaper if you buy used.
  7. guyharrisonphoto

    guyharrisonphoto ScubaBoard Supporter ScubaBoard Supporter

    # of Dives: 1,000 - 2,499
    Location: Florida, USA
    For your conditions, it should be fine, so long as, like Dr. Mike says, you are not planning to exhaust your primary supply and then use the spare air to surface.

    I saw Caruso's comment, but do not agree that, for a solo diver (or any diver), a pony should be part of gas planning by letting you deplete your reserve. Use your primary cylinder for gas planning--the pony is only for an emergency, so do a gas plan as if it will never be used. If you want more bottom time, use a bigger cylinder, not the pony.
    Steve_C, Esprise Me, lv2dive and 4 others like this.
  8. certainmisuse

    certainmisuse Nassau Grouper

    # of Dives: 100 - 199
    Location: Atlanta GA
    I agree with everything here except the deployment time vs. getting up from 30'. These are always turned on, and with the right placement, it should be as quickly as you can grab off your chest and insert into your mouth.
  9. certainmisuse

    certainmisuse Nassau Grouper

    # of Dives: 100 - 199
    Location: Atlanta GA
    Eh, it's more than a couple, from shallow depths that is. I believe the 3 cu. ft. is 50 breaths or so on the surface, depending on your SAC.
  10. scubadada

    scubadada Diver Staff Member ScubaBoard Supporter

    # of Dives: 1,000 - 2,499
    Location: Philadelphia and Boynton Beach
    Having air is much better than not having air, I'm not interested in making a CESA. I could make a normal, direct ascent to the surface from 60 ft, at twice my average RMV, using a 3 cf Spare Air. I could make a normal, direct ascent from 90 ft or a little deeper, at twice my average RMV, using a 6 cf Spare Air

    I dive with a 19 cf pony and can spend a minute at 130 ft, make a normal ascent and a safety stop, at twice my average RMV :)

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