Lowest SAC possible ? (without being dead)

[bradshsi]

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

In that thread the person posting stated that they

can dive three one hour 60 foot dives on a single AL 80.

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.

 

[eagerbeaver]

Hi bradshsi,

My answer is 'I haven't a clue'; but in the spirit of 'net forums i will post anyway and astound you with my ability to sound like I know what I'm talking about without actually saying anything!

I imagine the quoted diver is talking about dives with a max depth of 60ft, and a fairly mild multilevel profile after that. I have met a number of people with SAC rates that are very low, but without checking your clacs .15 does seem to be pushing it a little bit. If he actually did a proper calc I'm sure he wouldn't get 0.15

So haven't not answered your question, I'm off!

Cheers,

Matt.

 

[jeckyll]

I've read of some experienced divers down in the 0.3x's.

Me. Phhht yea.

 

[Snowbear]

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

That would depend on the diver. Some folks just need more air than others. What is enough for one person (say a sac of .4) may be too low to support life for someone else.

 

[rockjock3]

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

In that thread the person posting stated that they

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.

Me thinks he was either trolling or didn't know enough about SAC rates to know that those numbers are pretty much BS. I too have heard some divers having SAC rates in the .3Xs. I think it would be hard to consume less air while diving though than when sleeping. You really can't get more at rest than sleeping.

I average (per my computer logging) .42-.45. With about 3 dives I have gone about .47 and one dive I actually managed a .34 (drift dive), But to manage a .15 I think somebody would have to stop breating.

Maybe his 3 60ft dives are on different days and he forgets filling his tanks between each dive. Heck, even one 60fsw dive for one hour gives a very respectable SAC rate of .47.


p.s. my diving is in Oahu with a current water temp of about 73-75 and a summer/fall water temp of 78-81.

 

[DiverBuoy]

Uncle Pug did a 3 hour dive averaging 12 feet of water on an AL 80 ... I'm impressed, I didn't do the math but I think that's a smidge around high .3s low .4s which alone is impressive, but considering the dive itself was 3 full hours submerged is a bit more impressive.

I personally range between 3.3 and 6 ... depending on a myriad of contributing factors.

 

[rockjock3]

Uncle Pug did a 3 hour dive averaging 12 feet of water on an AL 80 ... I'm impressed, I didn't do the math but I think that's a smidge around high .3s low .4s which alone is impressive, but considering the dive itself was 3 full hours submerged is a bit more impressive.

I personally range between 3.3 and 6 ... depending on a myriad of contributing factors.

My calculator shows it about .28 if he came up with 500psi. Very impressive indeed.

 

[DiverBuoy]

nah I think he said he sucked the tank dry then held his breath (j/k) ... I can't remember the details, perhaps he could fill them in when he catches wind of this thread.

 

[bradshsi]

Me thinks he was either trolling or didn't know enough about SAC rates to know that those numbers are pretty much BS.

Just for the record, the poster in question has a profile stating that he's done several thousand dives. So I would think that he would have mastered SAC calculations by now.

The 0.15 number seems very low according to my limited knowledge of human physiology. However I've seen yogis in India being burried alive and/or apparently be dead, only to recover afterwards. Supposedly some of these people can reach a state of almost suspended animation.

Then again how many yogis do you see diving ?

My inclination is to think that the poster is disingenuously missing something out (such as the AL80 in question was a fibre wrapped one pumped to 5000 psi). But for the sake of enquiry I thought I'd ask the question to see what is possible.

 

[Kim]

Uncle Pug did a 3 hour dive averaging 12 feet of water on an AL 80 ... I'm impressed, I didn't do the math but I think that's a smidge around high .3s low .4s which alone is impressive, but considering the dive itself was 3 full hours submerged is a bit more impressive.

I personally range between 3.3 and 6 ... depending on a myriad of contributing factors.

Nah....I heard Uncle Pug can start with an empty tank and come back with 1200psi after 2 hours. He's really not a good example!