Average Gas Consumption

What is your average RMV?

  • less than 0.3 cu ft/min, 8.5 l/min

    Votes: 12 1.6%
  • 0.3-0.39 cu ft/min, 8.5-11.2 l/min

    Votes: 85 11.5%
  • 0.4-0.49 cu ft/min, 11.3-14.1 l/min

    Votes: 193 26.2%
  • 0.5-0.59 cu ft/min, 14.2-16.9 l/min

    Votes: 229 31.0%
  • 0.6-0.69 cu ft/min, 17.0-19.7 l/min

    Votes: 107 14.5%
  • 0.7-0.79 cu ft/min, 19.8-22.5 l/min

    Votes: 77 10.4%
  • 0.8-0.89 cu ft/min, 22.6-25.4 l/min

    Votes: 15 2.0%
  • 0.9-0.99 cu ft/min, 25.5-28.2 l/min

    Votes: 7 0.9%
  • greater than or equal to 1.0 cu ft/min, 28.3 l/min

    Votes: 13 1.8%

  • Total voters
    738

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I use memorized values to gauge stress level during the dive.
Memorized values of what?
Stress is different than air consumption.
 
0.26? That's a crazy low SAC - you must have gills :)! The best I've achieved to date was on my November Aruba trip where I was consistently below 0.4 and got as low as 0.35.
I'm lucky, my average RMV over the last 1669 dives is 0.36 +/- 0.04 cu ft/min (mean +/- std dev) I attribute my low gas consumption to having been a competitive swimmer from the age of 4 through high school. I don't really know the answer. I did learn an effective breathing pattern for scuba. My gas consumption has always been on the low side, 1970 to now. I am not svelte, 5'10", about 180-5 lbs. I have exercised about 6 days/week for my entire adult life. I'll be 68 years old next week, I'm doing just fine.
 
I have understood that RMV (as a correctly define technical term) is independent of depth; it is a physiological concept that describes the uptake in the lungs, at the surface, for example 0.7 cuft/min or 20 l/min. If I increase my ambient pressure to (say) 3ATM, it isn't RMV that changes, it is just the amount of gas I breathe in 1 minute. So I can't say my RMV has tripled...it stays the same. It is my gas need that triples.

In a perverse sort of way, SAC also doesn't need to be stated as at 1 ATM; the S in SAC does that. Similarly to RMV, if I go to 3 ATM, my SAC doesn't change, only my gas needs.

Perhaps all would be clearer if Shearwater -- and others -- did not display SAC (or RMV, for that matter) during he dive but rather displayed psi/min or cuft/min AT DEPTH, so you can more easily see that you are using gas up faster if you are deep. If I glance down and see that SAC stays at 31 psi/min while I am diving, perhaps I might misinterpret that.
As you correctly point out the SRMV is useful in predicting gas use at any depth, its major value in gas planning.
 
As you correctly point out the SRMV is useful in predicting gas use at any depth, its major value in gas planning.

Nevertheless, he persisted. :)
I can never tell what you are doing, you are older than me., and even more obtuse :)

Ah, maybe I got it, it's the S, right? I like the S, just too confusing to everyone else
 
I can never tell what you are doing, you are older than me., and even more obtuse :)

Ah, maybe I got it, it's the S, right?
Right. Completely unnecessary, and potentially even more confusing, as you suggest.
 
Since lung volume doesn’t change when you are scuba diving, do we need that “S” in SRMV?
 
Pressure and gas density change at depth. That’s why we need to put “S” on SAC.
 
https://www.shearwater.com/products/teric/

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