What's a decent SAC?

[Brandon]

So Pug's Hoover thread got me thinking... what's a decent SAC rate for a new diver? I have about 35 logged dives under my belt, and was just going through my logs calculating SAC. It's improving, but I still have a ways to go.

For the chart, I picked about half a dozen non-training dives from my log that didn't have a notation for struggling with current/surge/being new or swimming quickly while chasing things.

Dives 8, 9, and 29 are Alaska dives during the winter... big improvement in dive 29 compared to 8 and 9.

10-17 are all Maui dives, pretty stable with the exception of Dive 17, which was a solo dive at Black Rock... most relaxing dive ever.

Was in the pool about a month ago, didn't track tank pressure or time very accurately, but guestimating a SAC of around .55

I'll post again when I get back from Maui.. but how's my SAC looking?

-Brandon.
Aspiring Dust Buster Diver.

Edit: Attached another chart with estimated bottom times. I'm bored, and SAC/RMV is cool.

 

[steelslinger]

that aint bad. I will get to a .4 in summer but a .55 is good.

 

[dilligaf368]

Don't worry so much on how much air You breath. Just concentrate on doing the basics. Lots of divers like to compare like it is somekind of metal because they breath slower.
Commercial divers are the worst with limited air supplies. After diving everyday for months, I'll forget to conserve air. So what? I just buy the largest bottle I can so I don't worry about metals. In the Navy we were taught to skip breath, yes, I know....but combat divers did lots of stuff back then. That was back during the "police action" in south east china.
The primary thoughts should be of safety. That is what make old divers. I have been diving for 32 years (before the "police action") and haven't been bent yet. Remember to breath and watch Your air. The rate of breathing comes later.
Also the cold water diver will use more air than warm water divers. Not my opinion but of the Navy and Taylor diving in La. joint investigation of using warm water divers incase of an emergency in cold water. (Northern latitudes) Bill

 

[Uncle Pug]

I agree with dilligaf368... don't worry about it. However I will say that the trend shown above is good... so now just forget about it and have fun diving for a while.

SAC is useful for gas management...planning your dive based on the gas available or taking the appropriate amount of gas for the dive planned. Frankly... you probably aren't doing the kinds of dives where such planning is necessary.

When you do... you will need to know your working SAC, resting SAC, stressed SAC. Have fun and don't worry about SAC for another 50 dives. Then calc your SAC again like you did above to get a baseline for gas planning.

For dives where we actually need to do gas planning I allow .66 cf/m working, .50 cf/m resting (deco) and 1.0 c/pm stressed. This is not my actual SAC... it is prudent to fudge upward.

note: SAC is usually expressed in psi/min and is tank specific. RMV is expressed in cf/min and is not tank specific but needs to be converted to psi to be read on an SPG. Since most folks posting questions/comments about SAC express it as cf/m (as does the Suunto Dive Manager software) I usually refer to SAC in those terms as well.

 

[Brandon]

Oh... I see... NOW you tell me it's not worth fretting about! I started reading the Hoover thread and was scared that I'd be violently beaten by a 350lb football player if my air consumption wasn't acceptable.

Now I have to cancel the order for the 250cf tanks! I'll just have to make do with a half dozen bandolier mounted spare airs!

-B.

 

[shugar]

how do i calculate for SAC exactly? how do i take max/ average depth into consideration?

Jag

 

[Brandon]

http://www.spearfishing.org/bruces_tips/java/sac.html

Java SAC Calculator.

-B.

 

[mania]

OK as you guys are again using the imperial system it's difficult for me to figure out the numbers. Anyway - good SAC for women is between 8 - 12 liters. For men 12 - 15.
I'm somehow lucky - my average SAC is 8 - 10 liters. But it also depends on the day, tiredness, mood and the level of stress.
Mania

 

[vjongene]

OK as you guys are again using the imperial system it's difficult for me to figure out the numbers. Anyway - good SAC for women is between 8 - 12 liters. For men 12 - 15.
I'm somehow lucky - my average SAC is 8 - 10 liters. But it also depends on the day, tiredness, mood and the level of stress.
Mania

1 cf = 28.32 l

So your SAC in non-conventional units is between 0.28 and 0.35 cf/min

I use about 0.4 cf/min (11 l/min) in warm tropcal waters, and about 0.6 cf/min in the cold waters of the lake.

 

[Rick Murchison]

what's a decent SAC rate for a new diver?

Yours is decent... now, go forth & dive, dive, dive.
S