How small is your SAC?

[JohnE]

Consistent dives at 26' for work. 0.55 low activity, 0.85 high activity - same gear. I didn't see a great drop of air consumption going to my drysuit from my 7mm FJ wetsuit (50-52F water temp avg).

For me I think the wetsuit shiver factor for air consumption becomes more of an issue on 3rd/4th dive of day. I also probably burn too much air in my suit keeping things fluffy. I like my feet a teeny bit floaty for warmth. I probably need to improve my 1st layer especially arms and chest.

 

[Dtaine]

Let's see, I compared a very leisurely dive of the Benwood wreck to a very exhausting shore dive off Dania Beach.

Benwood: .46

Dania Beach: .89

I'll stick to wreck diving for now.

 

[Hyper-limits]

I only used 4 to 5 cuft of gas per hour of diving at 10ft or 200ft is that a good SAC rate. Seriously on OC I'm between .5 and .6 which is not bad.

Cheers

Al

 

[nereas]

Yeah. Agree. Fun to brag about, but in the end it really has no bearing on whether one is a good diver or not, or their level of skill. Though when bottom time is not a factor (I do a lot of shallow diving) it is more fun for me to have somebody who can stay down as long, whether it be low SAC or big tank.

There is a slight trade off that works both ways.

I can lug twin 130s. I have never met a woman who can do that. Nor would I want to.

And with the twin 130s I can stay down as long as any woman with any tank(s).

Now, a woman with a lite weight CCR can still beat me, of course.

 

[BHB ScubaTroll]

Hmmm,

SAC rate changes dynamically with output. If I take my SAC resting at say, 20' it is much different when I exert energy at even 10'.

A challenging dive will give a different SAC rate than a non-challenging dive.

A deep challenging dive will give a different SAC rate than a deep non-challenging dive...
===

Honestly, SAC rate differs on "EVERY SINGLE DIVE" based on a chaos theory of information...

 

[Charlie99]

0.35cfm just hanging around watching something.
0.4-0.45 cfm doing a 1/2 knot putter-around-the-reef.
0.5 to 0.6 doing a 1 knot transit.

More specifically, this morning's dive was 53 minutes, 1400psi out of an AL80, average depth about 30', water temp 78, 3/2 full wetsuit + beanie, out to the turtle cleaning station and the 45' patch reefs at Ulua. This calculates out as a bit under 0.7cfm actual consumption at depth; a bit under 0.4cfm/ata SAC if the average depth is 25'.

 

[Buoyant1]

I haven't figured it out the way my one instructor friend suggested, but according to my dive log software, I'm averaging between .60 and .70 on a fairly consistent basis.

 

[Luis H]

Gas consumption at home, in cold water, is more in the low to mid .4's. I don't know why cold water raises my gas consumption, but it does.

As far as I know, everyone's air consumption goes up in colder conditions. Even with the proper insulation. The proper insulation helps you feel warm and reduces heat loss, but as long as there is a large temperature gradient, there will be a large heat flow.

From a simple engineering perspective more heat flow requires burning more fuel to maintain the temperature (and burning more fuel requires more air/ oxygen). Even in very low effort activities, it is typical to be tired and energy depleted after long exposure to any cold or windy condition (what is a "long exposure" is relative to temperature and conduction/ convection media, as in water).

I realize the human body is far more complicated, but the same basic physical principles tend to apply.

 

[DwayneJ]

It would be helpful to know the average depth at which some of these SAC rates were achieved otherwise a pointless measurement by itself.

 

[ScubaSteve]

It was pointed out long ago that the Poll is flawed but it is fun to play along anyways. After all you are getting a pretty wide spectrum of involvement (divers with 25 to divers with 2500).