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Average Gas Consumption

Discussion in 'Basic Scuba Discussions' started by scubadada, Jul 3, 2016.

What is your average RMV?

  1. less than 0.3 cu ft/min

    4 vote(s)
    1.0%
  2. 0.3-0.39 cu ft/min

    49 vote(s)
    12.5%
  3. 0.4-0.49 cu ft/min

    108 vote(s)
    27.6%
  4. 0.5-0.59 cu ft/min

    115 vote(s)
    29.3%
  5. 0.6-0.69 cu ft/min

    59 vote(s)
    15.1%
  6. 0.7-0.79 cu ft/min

    36 vote(s)
    9.2%
  7. 0.8-0.89 cu ft/min

    9 vote(s)
    2.3%
  8. 0.9-0.99 cu ft/min

    3 vote(s)
    0.8%
  9. greater than or equal to 1.0 cu ft/min

    9 vote(s)
    2.3%
  1. BLACKCRUSADER

    BLACKCRUSADER Manta Ray

    # of Dives: I'm a Fish!
    Location: Taiwan
    968
    571
    93
    You will improve a lot over time. One new diver here has gone from first dives in December 2020 with sac of 20l/min to less than 12l/min from changing the way he dives. But he has now done I think over 50 dives. Regular diving you can improve a lot for sure.
     
  2. JimBlay

    JimBlay Divin' Papaw ScubaBoard Supporter

    # of Dives: 500 - 999
    Location: Southern Florida
    1,003
    1,683
    113
    I'm very late to this thread but better late than never. I just ran a calculation of my average RMV since getting my Perdix AI. That is over my last 119 dives. My average is 0.46 cfm. I've responded to the poll based upon that average.

    I also ran MIN and MAX as well. My MIN was 0.32 cfm and my MAX was 0.61 cfm.

    I was very late coming around to an air integrated computer but I sure do love the data it makes available to me!
     
    inquisit, scubadada and BLACKCRUSADER like this.
  3. scubadada

    scubadada Diver Staff Member ScubaBoard Supporter

    # of Dives: 1,000 - 2,499
    Location: Philadelphia and Boynton Beach
    13,607
    9,679
    113
    Wow, there have been 22 more responses to the 2016 poll since the last update. This is probably one of the most active polls on SB. Remember, you are able to change your vote in this poll if/when your average RMV changes. In the 2016 poll, the median and mode are both 0.5-0.59 cu ft/min. The weighted average also falls in this range. Thanks for all the responses and posts :)

    upload_2021-1-13_12-7-45.png upload_2021-1-13_12-8-31.png

    See post #1 for imperial/metric conversion
     
  4. stepfen

    stepfen ScubaBoard Supporter ScubaBoard Supporter

    # of Dives: 200 - 499
    Location: Greece
    702
    511
    93
    Welcome to scubaboard. We have somewhat similar figures (now I am 90kg and 190cm but I use to be around 110kg since I started diving in 2016 and until the end of 2019).
    To get an idea what to expect here is how my SAC evolved over these years:

    Year // No of dives // average SAC (lt/min)
    2016 // 26 // 21.8
    2017 // 29 // 17.1
    2018 // 67 // 16.4
    2019 // 90 // 14.7
    2020 // 55 // 13.3

    First year or so I was trying actively to reduce my SAC (tried breath control, singing while exhaling and whatever other bullsh*t recipe I would find around). Nothing really worked. Then thanks to scubaboard I stopped worrying about SAC itself and focused on diving as much as possible (to become more comfortable underwater) and tried to become a better diver (improve my buoyancy, my trim, my technique etc). Reduction of SAC followed naturally.

    All the best
     
    scubadada and JimBlay like this.
  5. JimBlay

    JimBlay Divin' Papaw ScubaBoard Supporter

    # of Dives: 500 - 999
    Location: Southern Florida
    1,003
    1,683
    113
    That's awesome and I love the data to support it. I've found by experience that the important elements of keeping my SAC down are (1) getting/staying comfortable (2) working as little as possible (3) staying physically fit (4) deep, slow breathing.

    Any changes to any of those factors drive up my SAC. If I'm cold, stressed, forced to work hard for some reason, in new equipment I'm not comfortable with, in a new environment I'm not yet comfortable with, etc. ... BAM ... SAC goes up sometimes markedly.
     
    scubadada likes this.
  6. scubadada

    scubadada Diver Staff Member ScubaBoard Supporter

    # of Dives: 1,000 - 2,499
    Location: Philadelphia and Boynton Beach
    13,607
    9,679
    113
    Hi @stepfen

    Great data, thanks for sharing. In 5 years and 267 dives, you have reduced your RMV by 40% and now have the same average RMV as our SB friend, @JimBlay

    My gas consumption has always been pretty good, but I did not start following my RMV until I was at 443 dives. In the next 10 years and 1500+ dives, my yearly average RMVs have only varied by 0.04 cu ft/min (1.1 L/min). It appears my RMV was essentially fixed by the time I started calculating it. I am at the lower end of the tight range and variability has decreased a little.
     
    JimBlay likes this.
  7. stepfen

    stepfen ScubaBoard Supporter ScubaBoard Supporter

    # of Dives: 200 - 499
    Location: Greece
    702
    511
    93
    One important factor that kept my SAC high for the first year or so was me worrying about it too much. Then I realized that ending a dive a bit earlier than the rest was not a huge deal. This, together with getting more comfortable and gradually better technique were for me the most important factors at the beginning.

    Nowadays I agree with all of the factors @JimBlay mentioned above and I would add (at least for me) that diving solo also has huge (positive) impact to my SAC.

    When with a buddy (or even worst in a group), I simply can't relax enough. As I said I am a (relatively) big guy and I hate being disturbed but also disturb other people. When there are divers around me I constantly worry that I am disturbing somebody or that I will get disturbed (eg squeezed to the reef). Also when group diving, one needs to follow the group which usually means chasing the freaking dive guide. Do they do it on purpose (swim fast, make customers finish their air faster, finish dive faster, go home faster) or is it just my impression?

    When I dive solo I am in paradise - all by myself :)
     
    BLACKCRUSADER, scubadada and JimBlay like this.
  8. ATJ

    ATJ Barracuda

    # of Dives: 1,000 - 2,499
    Location: Sydney, NSW, Australia
    444
    269
    63
    Another factor for SAC/RMV is not getting cold. My SAC/RMV can skyrocket when I get cold.

    I now pretty much dive all year around in my drysuit. I'm comfortable and my SAC/RMV stays pretty constant.
     
    JimBlay likes this.
  9. DivingColeridge

    DivingColeridge Divemaster

    # of Dives: 100 - 199
    Location: Christchurch
    52
    25
    18
    When I'm cold my SAC is around 20lpm(0.7cfm) and when I'm warmish it goes as low as 13lpm(0.48cfm). My all time highest was running and swimming around in freezing water with no fins carrying rocks, and that was 38lpm(1.3cfm)
     
  10. BBking

    BBking Garibaldi

    2
    1
    3
    Yeah, figured this out. At least, as the instructor said, you always have spare air in your wife's tank :D

    Thanks! And thanks for data!

    And about worrying about SAC. On the one hand, I heard about it: "Just dive, man! No worries" and this is true in my opinion, but on the other, thanks to worrying abount SAC, I read a lot of related literature and found out some good info.
    E.g, about weighting :D Started with 10 kg in shorty suit, and now its only 5kg in 5mm full wetsuit. Or diff between steel\aluminium tanks etc
    I mean, its better to know, than not to know.
     

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