How's your SAC?

During AOW, one of the things we were taught was how to measure our SAC. We went through the calculations and logged it after each dive, but none of the instructors gave us any idea of what an average or good number is. Is it one of those things where guys just don't like to compare SACs? What's a good number?

OK, I'll throw out one . . . 0.45 cfm

My last dive in 49 degree water at 55' yielded a 0.36 cfm. based on a dive of 47 minutes with an average depth of 44'.

jpedwards:

During AOW, one of the things we were taught was how to measure our SAC. We went through the calculations and logged it after each dive, but none of the instructors gave us any idea of what an average or good number is. Is it one of those things where guys just don't like to compare SACs? What's a good number?

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There is no such thing as a good number ... your SAC rate is based on a number of factors ... including your comfort level in the water, your physiology, the type of exposure gear you're wearing, weighting, and water conditions. A good number for you might be 0.65 CFM, whereas for someone else it might be 0.40 CFM.

I teach my AOW students that the reason they want to calculate their SAC rate is so they can use it for dive planning. By knowing your SAC rate ... and that of your dive buddy ... you can figure out how long, and at what depth, you can plan your dive. Or, if you have a specific objective in mind, you can calculate how much gas you'll need for that dive and make sure the cylinder you're planning to use will get you there and back.

Calculating SAC is also a good way to track your progress as a diver ... as you get more experienced and learn how to dive more efficiently you should see your SAC rate dropping ... sometimes significantly.

But it's misleading to suggest that there's a "good SAC rate" that would apply to a given group of people. It's widely variable ...

... Bob (Grateful Diver)

We did a dive the first part of May just to compute our SAC.

Carrying my double 100's all my gear and a AL80 and a AL40 we did 120' for 25 minutes. Measured the amount of gas used during 20 minutes of swimming at 120 then the deco.

With all my gear and in 40 degree water I am about .65 and about .6 on deco maybe a little less. For planning purposes, I use .7 and .6.


Dave

jpedwards:

During AOW, one of the things we were taught was how to measure our SAC. We went through the calculations and logged it after each dive, but none of the instructors gave us any idea of what an average or good number is. Is it one of those things where guys just don't like to compare SACs? What's a good number?

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Mine is about 0.4 in warm tropical water. I just started cold water diving again (diving wet, 48 degrees), and I am averaging 0.55 to 0.6. I expect after a few more diving days getting used to the new wetsuit and dropping weight from my weightbelt, that number should begin to come down.

I had gotten mine down to 0.55-0.6 (as calculated by my Sensus Pro software) before doubles.. now it's up to .65-.7

last saturday i logged dive #10, that dive i was .62.... 3 dives prior to, i was at .70


like everyone sez, there are many variables

jonnythan:

I had gotten mine down to 0.55-0.6 (as calculated by my Sensus Pro software) before doubles.. now it's up to .65-.7

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That's pretty good!

My SAC rate goes up almost 50% when switching from singles to doubles ... then again, so does everything else ...

... Bob (Grateful Diver)

If I'm with open water students it's over .55. If I'm with my wife on Maui it's way lower, usually about .40-.42. I'm overweight, old and sorta outta shape but I've logged thousands of dives.

As others have mentioned, it really depends on the dive. I've heard that .7 is the "average". For me, the numbers can really vary, but usually average in the .4 to .45 range. It just really depends on the dive and the conditions that day. If I am doing an easy drift dive in West Palm (i.e., Breakers) - my SAC rate drops down into the mid to high .3's. My lowest on record was a night dive on Pauls reef. For some reason I didn't breath that dive I guess and got a .32 SAC. But just two days ago I did the Rankin in 120 feet of water and a 4 knot current. May SAC rate was .68 for that dive. Dragging my overweight rear end down that anchor line against that current burned a TON of air!

Gender and size also plays a HUGE role in your SAC rate. In general, women have much better air consumption. Smaller frames and smaller lungs.