What is your average Air Consumption?

[jhelmuth]

...typically .45 or .46 on leisure video dives...
I've been up there in the .60+ in strong currents and work-like conditions. These rates are from the most recent 30 dives (my rates where higher in my first 20 dives).

 

[DeepScuba]

I believe DivemasterB has summed it up quite well.

It's evident to me, that conditions (warm/cold water) has a greater effect on SAC rates than one would expect to find.

It's already on my agenda, for my next pilgrimage to Mecca.......Uhmmm Trip to Cozumel , that I am going to run several SAC rate checks.

This for me will tell the tale. I should be going there in November.
Oddly enough Charlie, to Scuba Club!

Did you mind-meld me with you last post???

Regards.


P.S. Now lets take a look at that "PAUSE" between breaths. How long of a pause is too long, how many skip breathe, or close to it?

What about that video I watched (and listened too). That was one long pause (To me).

 

[Charlie99]

DeepScuba once bubbled...
This for me will tell the tale. I should be going there in November.
Oddly enough Charlie, to Scuba Club!

Now lets take a look at that "PAUSE" between breaths. How long of a pause is too long, how many skip breathe, or close to it?

Hmmmm. I don't have any trips setup for November. Always a good time for Cozumel!

If you get a CO2 headache, then you are breathing too slowly. (or too shallow --- I used to have CO2 headaches when I first started diving, but that was more a case of not breathing deep enough to get good ventilation.)

Breathing very full inhales followed by very full exhales reduces the effect of the dead space mentioned in Steven Ash's excellent post. Breathing underwater is NOT like breathing on land. At least for me, underwater breathing is deeper breaths at a greatly reduced respiratory rate (breaths/min).

As I've mentioned in posts regarding ESAs, the key safety issue is to NEVER CLOSE THE AIRWAY. This is NOT the same as the more often propagated warning of "always be breathing in or out" or "never hold your breath".

Regulators vary greatly in how they feel at very very slow inhale rates. IMHO the Atomics excel in a nice smooth air delivery at slow rates. Using a typical rental reg increases my SAC signficantly.

 

[Epinephelus]

I went ahead and answered based on my "normal" relaxed warm water dive rate of .45 CFM. But during deco it can get as low as about .37 and on a working or spearfishing dive as high as 3 CFM (and on one particularly exciting dive involving some bull sharks it shot up to over 3.7 CFM!).
So..... what's the question really?
Plans must include a good idea of the activity for the dive, and SCR adjusted accordingly in the gas plan.
E.

 

[DeepScuba]

Good posts Charlie and "E".

So does EVERYONE breathe like this cave diver?? It sounds like he's trying the create the "vacuum of outer space" when he inhales, and then there's one hell of a pause........I'm falling off my chair waiting for the exhale!!!

I'm trying to breathe for the guy!!!

Haha 3.7cf/min....I hear ya buddy!!! I think I once blew 400-500 PSI pulling, hand over hand, down a line, to 20ft depth (3-4 minutes?)against a raging current.......NO I didn't count that one as part of my "normal" SAC rate!

I almost bagged the dive it was so bad.

How I long for 78 degree, crystal clear "easy" water..........

 

[Genesis]

Had one dive earlier this summer where the current on the surface and down to about 30' was so bad that you HAD to hand-over-hand, and if you turned your head it was bye-bye mask!

Once you got down to 30' the current disappeared though....

From the back of the boat to 3' of depth I "lost" close to 1000 psi! My computer doesn't count that though in SAC computations, as it doesn't go into "dive" mode until you reach 3' of depth... but the SAC for that few minutes was righly scary

I kept going, but had every intention of turning if it didn't go away... it did....

On the way up it wasn't so bad - just don't lose the line!

 

[drbill]

Since I usually get 2-3 dives out of my HP120 tank, I can't really calculate my rate of air consumption from my dive log. On the few dives I know I used an "entire" tank, I didn't record what my remaining air pressure was. Assuming I sucked the tank dry on those dives (which I didn't), I'd be consuming less than 1 cu ft/min (0.85). If I left 500 psi in the tank, it may be as low as 0.66 cu ft/min (vased on an average cold fill pressure of 3200 psi).

This would be in cool (~65 F) southern California waters probably with a 3mm shortie in early summer (June). My female buddies have comparable or higher rates and consider me a "sipper." I assume the extremely low rates reported here are all in warm water

Dr. Bill

 

[DeepScuba]

Yeah, that cool (~65 F) water's a bittch isn't it! "***" avoid ON

Hahahah

 

[drbill]

DeepScuba- Note I said "cool" not "cold" although during winter we may get bottom temps in the upper 40's.

Dr. Bill

 

[Rick Murchison]

I find that gas consumption rates are consistently underestimated in my more advanced classes (Advanced Nitrox, Rescue etc).
Must be the challenge of precision - a 50% increase in consumption rate over what they estimate is typical while doing the exercises (not the strenuous ones, but rather the precision ones).
Which begs the question... what kind of rate do you use when planning a dive on a site that presents new and possibly difficult challenges?
As Pug alluded, your rate isn't particularly important with reference to "bragging rights" - but it is absolutely essential to safe planning.
I see that at least one diver needs to make it a pretty short plan if shark wrestling.
Me too.
Rick