Lowest SAC possible ? (without being dead)

[CD_in_Chitown]

I am sure that the right person in good enough physical condition with enough dive experience could get below .2.

I don't think so, no offense to Hal but .2 is really unrealistic. People use more air sleeping, and you can't get more relaxed than that without channeling your soul somewhere else and that would double the SAC of whoever you possess I figure.

I love my instructors too, but I know they are not defying the laws of physics to be as good as they are.

 

[Talon]

I love these discussions.... Let's start here. Bullsnot on the poster who claimed .15. I say challange him to a contest. Put him in a locked container with just enough air to support a SAC rate of .15 for one hour. Tell him we will open the container after 58 minutes. My bet is the guy is dead in 25-30 minutes.

I can get my SAC rate down into the mid .3, but that is under ONLY ideal situations (warm water, relaxing dive, nice current, minimal swimming, and a little skip breathing thrown in). I know how much I breath when I do that. If I had to cut that in half.... I would be DEAD.

He would have been better off throwing around a .25 number. That is at least in the realm of possibility!

Michael

 

[**ping**]

The subject of a very low SAC came up in another thread I was reading.

In that thread the person posting stated that they http://www.scubaboard.com/showpost.php?p=1662772&postcount=36

Assuming they sucked dry a regular 77.4 cubic foot AL80, that equates to a SAC of 0.15.

For comparison, the typical SAC for a person sleeping is 0.22 and my average SAC on a good day in the warm and toasty Pacific NW is about 0.5.

So my question is what is the physiologically lowest SAC possible for a diver without him being dead, comatose or otherwise incapacitated (or unsafe) ?

We've had plenty of threads on average SAC but none that I could find on this topic. My apologies in advance if this has been discussed before.

Hmm.. that might be possible. My wife uses small tanks exclusively. Our dives are usually around the 60 fsw mark and last around an hour. When we come up, she normally has 1500-1600 psi left in her small tank, while I have around 700 psi left in a large tank.

Given that the small tank is one third smaller than the large bottle, she could squeeze out three 1 hour dives with a big tank.

But... and here is a big, big caveat:

My wife is not like other human beings.

She learnt swimming when she was 3 years old. By age six, she was in a swim team. By age 10, she was swimming competitively, by age 12 she did 12 training sessions of 2 hrs each a week, all in the water.

These days, she is a very, very good amateur triathlete.

She bikes everyday to work, even in a snowstorm in December in Chicago (nobody believes that, but it's ture).

Her weekly training schedule involves:

5x swim training (3 - 3,5 miles each in 1,5 hrs)
3x spinbike training
2-3x 8-12 mile runs

Plus some random stuff whenever she feels bored.

As a result, her resting pulse is 43... through swimming all her life, her body must have learned to make the most out of every breath underwater.

She is very, very streamlined while diving. She has to put in half the effort to cover the same distance than someone who is dangling all over the place.

So, I guess it is possible... just not for us normal people.

 

[homo maris]

I think the person has a more plausible SAC of 0.22 and not 0.15. Here is how I calculate it:

3 x 1 hour dives = 180 minutes
AL80 @ 3000 = 77.4 cf
Average pressure for a 60ft dive = (2.8+1)/2 = 1.9 ATA

SAC = air used / (pressure * minutes) = 0.22 cf/min

note that the 0.15 SAC was probably calculated with the diver staying at 60ft (2.8ATA) without taking into consideration the average pressure between 60ft and the surface .

0.22 seems achievale to me for a very experienced diver.
JL

 

[dannobee]

There's no way his SAC is that low, I'm also calling BS on this one. The only way it could possibly get that low is if he's a midget triathlete or a gnome, but most likely he's just a plain old troll. Yeah, that's it.

 

[cummings66]

But that is not what that poster claimed. He stated in no uncertain terms it was all done at 60 feet. He left you with the impression that he just dropped right down to it and that's all.

He didn't state how much air remained in his tank. If you consider that he should have had some sort of reserve his SAC could be even lower than the .15 which is for a 77.4 cf of air at 3000 psi, as low as .127 I think.

He's a low count poster so I tend to think he's stretching the facts to look super human to us mere mortals who'd be sucking water in half the time he is...

 

[Diver0001]

...never mind....

 

[lundysd]

It has been said that one of the locals down here (8000+ dives) can take an 80 with 500psi on a 30 minute dive to 80 feet. Is this exaggerated a little? Probably, but it's been said by several people who dive with him, so who knows.

 

[Diver0001]

She is very, very streamlined

I bet she is....

while diving.

oh.

R..

 

[**ping**]

Damn it!