What is your average Air Consumption?

[Diver0001]

I've been thumbing through old polls and to the best of my knowledge nobody has ever polled this.

The point of the poll is pretty obvious. To see if people have idea of their air consumption and to get a cross-section of what's normal.

I'm hoping it will also stimulate discussion about the usefulness of tracking your air consumption, the techniques people use for tracking air consumption and their methods for planning gas usage for diving etc. etc.

Let the fun begin.

R..

 

[coliseum]

 

[jbd]

its between 12 and 16 lpm depending on what I'm doing during the dive.

 

[jbd]

who don't know how to track surface air consumption rate(SAC) do a search here on scubaboard for respiratory minute volume. There have been several posts about this in the past. Once you are familiar with this it can be a useful pre-dive planning tool.

 

[SueMermaid]

Hmwhat?

Well, I use a maximum of approximately 2500 PSI per dive.

 

[Charlie99]

0.35 cu ft/min while in a coma or relaxing drift dive,
0.4 leisurely swimming,
0.5 at 1 kt transit,
0.6-0.66 -- this is waaaay too much work- I'm aborting.

I usually travel solo and thereby get exposed to lots of random buddies and their air consumption rates.

If someone doesn't know their SAC/RMV then it generally is around 2/3 or 3/4 cu ft/min. This includes the many people that say they are pretty good on air, but don't have a real number. This is based upon noting air consumption rates of many, many random buddies. (I generally calibrate our relative rates by comparing SPGs when I hit 2000psi -- after that I have a pretty good idea what they have in their tank.)

BTW, I find it humorous when someone tells me they don't have a clue as to their SAC, then later I note that they have an air integrated computer. hmmmmmmm.

 

[freedive]

I'm new to diving and right now working on extending my air time. Right now I'm trying to improve on my breathing habits. Not sure on my SAC rate but my average time for 2500 PSI is approx 60 minutes +/- depending on conditions.

 

[DeepScuba]

I've done a ton of dives while accurately measuring this, and I laugh when people say they're 0.40, or even 0.50

My wife is 3/4 fish, and she can keep up with ANYBODY's SCR, and she's 0.55cf/min/ATA for your "average" dive. (To us "average" is dry suit (the inflation is marginal, if your DIR tehheh in 40-50 degree water) You take it from there.

I'd challenge a whole lot of people to match her. I'm not even close if I try.

Sure, if I wanna skip breathe and do all the tricks to get it down, but to what end?

I know some people (some guys) are amazing, compared to other guys, but when they are put up to my wife, they seem to lose that incredible 0.40cf rate they say they have.

Crystal clear, 80 degree, wet suit, liesure dive..I'll give ya 0.10 to 0.15 better than our conditions, tops.

I'd suggest a recalc Charlie!!! If you're working, REALLY working, yo'd be easily 3 to 4 cf!!! NOT 0.30 to 0.40, but 3.0 to 4.0

Try it!

 

[Atticus]

I run about 0.7 on average when I'm not working hard. When I work hard I go up quite a bit. Charlie, I was surprised by your numbers as well - are you a really, really small, ultra-calm guy?

If I lay on the bottom, negative, with my eyes closed I can get down to about 0.4. This is what I would call "coma diving".

 

[Genesis]

An average look-around dive, or shooting video or pictures (which are very low-stress)? 0.35-0.45.

Spearfishing? Can be in the 0.6-0.7 range if I have to fight something big - that short burst of heavy breathing from shot to strung, dead fish is right nasty on your SAC.

If the current is REALLY ripping, I can easily get over 1.0, but that's too much like work and not enough like fun - a thumb typically gets displayed if that happens...

I found that my SAC went from 0.8 or so when first certified, to 0.6 or thereabouts roughly 20 dives later, and right around 80 dives the second drop took place. I noticed it when I started coming back with 1500 psi in my HP100s after my buddy thumbed on air reserve...... and said "hmmmm... what's that about?"

Friday I did three; the first was into a SCREAMING bottom current (barely swimmable; about an honest half to 3/4 knot) but absolutely gorgeous, so we stayed down there, current or no current. SAC was 0.55 for that one - pretty "bad" for a picture dive. The other two were significantly lower, and the last was i0.43, but I spent a good part of it keeping up with (to video) a Jewfish - and THAT was WORK! Had I not had that exertion my SAC on that dive would have likely been in the 0.35-0.38 range.

A couple of days earlier I did two dives on barges with essentially zero current, and recorded an SAC of 0.39 and 0.36.

I plan for 0.5 SAC on a "lookie dive", 1.0 if I anticipate work (spearing, etc.) If the numbers support it (time and gas) I will stay longer, but this way I don't get "surprised."

There is one person I dive with that consistently outbreathes me. She has amazing gas consumption - but she doesn't do stress-increasers (e.g. spearing.) Most of the rest of the people I dive with hoover by comparison, to the point that if I'm doing two relatively shallow dives I'll take a single HP120 to their twin AL80s and still wind up being the last one to become low on gas by a large margin. Its enough of a disparity that I have to be careful if they don't have a pony with them, lest they run out of air and I not have the reserve to support both of us on ascent.

(I have an AI computer and download my log, so I don't have to do any work to figure it out - its all done for me.)