SAC Rate

[Bructer]

What is considered good or even average? I'm 6'1 - 245lbs and in average shape and smoke cigars daily.

Reason I'm asking is because in the last year I've had to buy Steel HP 120,s to try and keep up with my wifes consumption. When I'm signaling i'm running low (3-500lbs) she still has 8-1200lbs left on a AL80.

My SLM on my last dive to 98' was 25.1 with a dive time of 37 minutes. (including stops)

Am I an air pig or what?

Any opinions would be helpful.

Cheers,

 

[Doc Intrepid]

Yeah you probably are, but so what?

Statistics such as "average SAC" are essentially meaningless to any specific diver. Who cares?

So long as you know your SAC and are planning your dives to take it into consideration safely, your personal rate of consumption relative to some mythical statistical average (for which very few if any empirically valid citations are available) doesn't much matter.

You may have some medical condition or some environmental parameter that skews your data relative to the general population.

What is important is that your SAC rate is relevant and valid for YOU.

Over time your SAC rate should improve as you relax in the water and gain experience. Newer divers frequently swim around a great deal more erratically than they do after they gain experience, and they accompany this with a lot of hand-wavery and gear adjustments and general bouyancy bozonity. It takes a while to dial things in, but once you get settled down and start to really relax your SAC rate will improve.

Thats whats really important. Don't worry about statistical averages. They're meaningless to your specific circumstances.

Best,

Doc

P.S. I am not an anti-smoking zealot, but knocking off the daily cigar smokery will improve your capacity to transfer and metabolize gas, may increase your endurance, and will very likely assist in signficantly improving your SAC and RMV rates ('respiratory minute volume' = gas consumption at depth). Its worth giving it up for safer diving, IMHO, even if not for the other health benefits. FWIW. YMMV.

 

[Teamcasa]

With the qualifications listed in your profile your SAC rate should be better than you posted. I would check your gauge, maybe it’s not accurate. Are you wasting too much gas to maintain buoyancy working with your students? Maybe your just nervous diving and worrying about your wife.

 

[Bructer]

Thanks for your response Doc, makes sense. Trip to the doctor may be in order.

I was certified in 84, and being from the prairies of western Canada, I don't get out diving as much as I'd like too. I was more concerned with SAC getting worse over the last couple years to be specific. My wife's (primary buddy) consumption has never changed in twenty years, actually has improved.
When in the water I feel like a fish, no anxiety, no jitters but just excited to be back under.
My wife thinks it has to do with water temp. I just cant handle the cold like I use to able to.

Our trip to Maui in a couple weeks will be the tell tale.


Cheers,

 

[Bructer]

With the qualifications listed in your profile your SAC rate should be better than you posted. I would check your gauge, maybe it’s not accurate. Are you wasting too much gas to maintain buoyancy working with your students? Maybe your just nervous diving and worrying about your wife.

No students. I have a hard time raising my 4 teenagers lately. We bought new Cobra2's about 6 months ago replacing old guages. I thought the same thing so I switched with her and ended with same results.


Cheers,

 

[battles2a5]

Check your gear, too. Gear tends to shrink over time and some people will unconsciously increase their breathing rate when their gear is restrictive. But ya, with your experience that sounds pretty high. You are a bigger guy so your body will likely require more air than your wife, but not in that order of magnitude.

 

[Scubakevdm]

What is considered good or even average? I'm 6'1 - 245lbs and in average shape and smoke cigars daily.

Reason I'm asking is because in the last year I've had to buy Steel HP 120,s to try and keep up with my wifes consumption. When I'm signaling i'm running low (3-500lbs) she still has 8-1200lbs left on a AL80.

My SLM on my last dive to 98' was 25.1 with a dive time of 37 minutes. (including stops)

Am I an air pig or what?

Any opinions would be helpful.

Cheers,

I've about the same body as you, and though I don't smoke anymore, I used to. For what its worth, I think I consumed less gas when I smoked, but essentially, I don't think that smoking matters very much. I don't know what an SLM is, but my SAC bounces around between .34 and .38. I dive around 600 times a year, and most folks consider me to be pretty good on gas. I don't know what kind of stops you were making, but in an AL80 I would have about 46 minutes worth of gas at 98 feet with a 500 psi reserve. I think that your 37 minutes is pretty respectable.

 

[battles2a5]

.34 = "pretty good"? I would say that is excellent. I run between about a .5 diving singles and I thought I was "pretty good". Maybe I just have a lot of work to do

And I think he was using a 120 for that dive. Based on the information provided (120cf tank breathed down to about 500lbs, on a 37 min dive to 98), and assuming the 120 is an HP, normal ascent/descent rates, a square profile, and a three-minute safety stop your SAC rate is a little over 1.0cf/min. That's a little high for an experienced diver, but definitely not out of the ordinary.

 

[spectrum]

My SLM on my last dive to 98' was 25.1 with a dive time of 37 minutes. (including stops)

Maybe I'm thick today, what does SLM stand for?

 

[Doc Intrepid]

.34 = "pretty good"? I would say that is excellent. I run between about a .5 diving singles and I thought I was "pretty good". Maybe I just have a lot of work to do

Maybe you only have one lung?

Maybe you only dive to collect shells and never go below 8'?

Maybe you have an abnormally high metabolism? Remember than many variables can impact gas consumption rates.

This is why comparing yourself against others, while it may be interesting, may also be an exercise in futility.

In fact, maybe its meaningless.

(But if anyone wants to brag about low SAC rates, or whose is lowest, fine. Just recognize that some folks are either genetically or circumstantially predispositioned to be different from other folks - either higher or lower. The playing field is definitely not level to start off with....so "whose SAC is lowest" is really sort of irrelevant to any specific diver's dive planning.....)