How deep can you theoretically go on single tank?

[Matthew]

An aluminum 80 has no place deeper than 100' and is in it's prime around 30'. Some very very simple math will show you why...below 100' and you basically have *no* contingency. If you don't know how to do that math, you shouldn't be diving deeper than 30' anyhow.

We regularly do dives to the 100-130 ft. using aluminum 80's and yes, we allow for contingencies. And we do it so often that we dont even need to do any math, my buddy and I already KNOW how much air the two of us would need to ascend, as well as when to ascend safely from that depth in even the worst situations possible.

Please stop assuming that everybody dives the same way, in the same conditions, same temperature, with the same skills/experience, the same SAC rate, the same profile, same tolerance to narcosis, with the same equipment, exposure protection etc.. as you.

 

[Don Burke]

Mark Andrews did one to 513ft. Damned psycho. He'll be the next one going for the deep trimix record.

R..

It appears he is pretty much set on either getting there or dying trying.

http://www.channel4.com/science/microsites/S/superhuman/contestants/mark/mark_profile.html

http://www.deeperblue.net/article.php/309/28

http://www.divingshop.co.uk/index.asp?fdPage=Diving_Articles.asp&fdQS=PageNo=7

http://www.undersea.ru/eng/accidents/acc2002.shtml

 

[jonnythan]

We regularly do dives to the 100-130 ft. using aluminum 80's and yes, we allow for contingencies. And we do it so often that we dont even need to do any math, my buddy and I already KNOW how much air the two of us would need to ascend, as well as when to ascend safely from that depth in even the worst situations possible.

Please stop assuming that everybody dives the same way, in the same conditions, same temperature, with the same skills/experience, the same SAC rate, the same profile, same tolerance to narcosis, with the same equipment, exposure protection etc.. as you.

Out of curiosity, how much do you each need to make a safe ascent from 130 feet under a stressful condition like an OOA?

 

[Rick Murchison]

An aluminum 80 has no place deeper than 100'

Everybody to their own kick. I do find that view a bit odd...
An 80 is as capable as any other bottle below 100'. It's how you rig it, how you plan it, what backup you have etc. etc. that determines whether *any* tank "has no place" below 100' - or any other depth for that matter.
I think it would be a bit more accurate to say that "a single point gas supply with no backup has no place deeper than the depth from which you can comfortably make a controlled emergency swimming ascent."
After all, 50 CF of gas is 50 CF of gas regardless of whether it's in an 80 or in a 120.
From a certain point of view - that of the potential for developing DCS - a single 80 properly managed is a whole lot safer than a larger gas supply in the 100-130 foot range. Just do the math!
Rick

 

[Rick Murchison]

Out of curiosity, how much do you each need to make a safe ascent from 130 feet under a stressful condition like an OOA?

Depends on you and your buddy's "stressed" SCR, doesn't it.. let's say .7 each... .7 X 3 X 4.3 X 38.8 X 2 = 700 psi to get both divers to the surface breathing from the same tank with no reserve. If you & your buddy stress up to 1CFM SCR then it'd take 1000 psi... well, actually a little less as if you were that stressed you're not going to take the full 4.3 minutes a 30FPM rate of ascent would require...
Rick

 

[Soggy]

Everybody to their own kick. I do find that view a bit odd...
An 80 is as capable as any other bottle below 100'. It's how you rig it, how you plan it, what backup you have etc. etc. that determines whether *any* tank "has no place" below 100' - or any other depth for that matter.

I agree. What I meant to say, I suppose, is that an Al80, rigged as a single tank, with no redundancy, does not contain an adequate reserve of gas to do a safe and controlled ascent with a safety stop *and* have a worthwhile (arguable) bottom time at depths much greater than 100'.

 

[Soggy]

well, actually a little less as if you were that stressed you're not going to take the full 4.3 minutes a 30FPM rate of ascent would require...
Rick

Why not? I plan my dives so I can do 30ft/min to around half max depth, then 10ft/min from there...or at the very least, do a 3 minute safety stop w/ a stressed SCR. Just because you run out of air doesn't mean you need to risk getting bent or embolized.

 

[Rick Murchison]

Why not? I plan my dives so I can do 30ft/min to around half max depth, then 10ft/min from there...or at the very least, do a 3 minute safety stop w/ a stressed SCR. Just because you run out of air doesn't mean you need to risk getting bent or embolized.

Nah, I've been watchin' divers for a long time, and trust me, breathing rate and ascent rate are directly proportional to each other.
Rick

 

[Charlie99]

Why not? I plan my dives so I can do 30ft/min to around half max depth, then 10ft/min from there...or at the very least, do a 3 minute safety stop w/ a stressed SCR. Just because you run out of air doesn't mean you need to risk getting bent or embolized.

When I have a truly freaked out diver sharing air, I'm willing to take the same DCS risk that divers accepted for years, and use up to a 60fpm ascent up to around 30', at which point I'll slow down. It's a case of balancing risks.

 

[jonnythan]

When I have a truly freaked out diver sharing air, I'm willing to take the same DCS risk that divers accepted for years, and use up to a 60fpm ascent up to around 30', at which point I'll slow down. It's a case of balancing risks.

IMO it would work much better if you calmed him down and settled things at the bottom BEFORE you bolt for the surface.. but that's for another thread. (I've been at the "dragged" end of an OOA who wanted to bolt and I have no desire to repeat it.)