CESA Training

[Dody]

I just went on the SpareAir website and I am starting to wonder if I am stupid. They claim they have bottles with internal volume from 3 to 6 cu. ft!!! That would make 80 and 160 liters. If it is rather the available air out of the bottle, it is very low. What did I miss?

 

[David Novo]

I just went on the SpareAir website and I am starting to wonder if I am stupid. They claim they have bottles with internal volume from 3 to 6 cu. ft!!! That would make 80 and 160 liters. If it is rather the available air out of the bottle, it is very low. What did I miss?

I am pretty sure @uncfnp was joking...

SpareAir is a recurrent topic / joke on Scubaboard.

 

[Dody]

I am pretty sure @uncfnp was joking...

SpareAir is a recurrent topic / joke on Scubaboard.

But why would anyone rate the cylinder volume by the available gas (which depends on the gas pressure) rather than the internal volume? If I have a 12 l cylinder, I will say 12 liters and not 2400 liters.

 

[Edward3c]

But why would anyone rate the cylinder volume by the available gas (which depends on the gas pressure) rather than the internal volume? If I have a 12 l cylinder, I will say 12 liters and not 2400 liters.

Because they're primary market isn't divers, but snorkelers.

 

[Scraps]

Just a reminder about the US Navy training video posted earlier---the trainees are required to exhale fully before beginning the ascent.

I’ve seen the video. I also talked with a guy who said he had to, as a result of his own carelessness, perform a CESA from 70 feet. Having just exhaled when he discovered he was out of air, he said he did not experience any benefit from air expanding in his lungs, but he did get one small extra breath on the way up as the air in his tank/reg/hose expanded enough to give one sip of air that he thinks made the difference in getting to the surface alive.

 

[Bob DBF]

Nope and nope, but when I was young and stupid (as opposed to old and stupid), I learned the hard way that on breathhold dives you don't ever exhale on the way up. Because the surface is much much farther than it looks.

I'm not a real trained freediver, but I do insure my airway is always open, and breathe out slightly towards the end of my freedives. I do that more for consistency with scuba so there won't be any mistakes in an emergency. It seems to work for me down to 40 something feet, ymmv.

So I actually see the point in training scuba divers to swim with their airway open. I'm not entirely on board with forcing the "A-hhhh" on the way up, but what you gonna do? -- the instructor needs to see bubbles.

When I did the submarine escape tank, it was hohohoho... all the way up, otherwise one of the tank divers would assist, which was not pleasant, I was told. It was a buyout ascent rather than a csea, a different animal but still works.

And your answer is "if will not happen'.

If one dives long enough, it will all happen.

 

[Coztick]

Good thread!
I see the spare air as better than nothing.
It's capacity can be quantified as the number of breathes available. Certainly not much gas but would make for a leisurely ascent as opposed to a cesa.
That said, I'm not a fan. I see your gas calculations as excessive. I don't see a need to triple the consumption rate as there should be no panic. You know you aren't ooa, it's just time to head up.
With an spg, you can monitor consumption and adjust accordingly. For NDL dives, the safety stop is not mandatory.
When on guided dives, I've never been asked to finish a dive with more than 1000psi. in an 80cuft cylinder. That works out to 13cuft for me and 13cuft for my buddy.
I went with a 13cuft pony myself but a 19cuft is also small enough to fit in a carryon bag for travel as well.
A CESA is mitigation for a complete "buddy system" failure. Your ONLY recourse is redundancy.
On vacation, my buddy options can be less than ideal... No way I'm relaxed if a CESA may be necessary! In fact, I refuse the risks.

Cheers!

 

[David Novo]

That said, I'm not a fan. I see your gas calculations as excessive. I don't see a need to triple the consumption rate as there should be no panic.

So basically you estimate your consumption in any situation based on your "steady state" SAC?

P.S.: According to PADI tables, between 30m and 40m the safety stop is mandatory.

 

[TMHeimer]

Good thread!
I see the spare air as better than nothing.
It's capacity can be quantified as the number of breathes available. Certainly not much gas but would make for a leisurely ascent as opposed to a cesa.
That said, I'm not a fan. I see your gas calculations as excessive. I don't see a need to triple the consumption rate as there should be no panic. You know you aren't ooa, it's just time to head up.
With an spg, you can monitor consumption and adjust accordingly. For NDL dives, the safety stop is not mandatory.
When on guided dives, I've never been asked to finish a dive with more than 1000psi. in an 80cuft cylinder. That works out to 13cuft for me and 13cuft for my buddy.
I went with a 13cuft pony myself but a 19cuft is also small enough to fit in a carryon bag for travel as well.
A CESA is mitigation for a complete "buddy system" failure. Your ONLY recourse is redundancy.
On vacation, my buddy options can be less than ideal... No way I'm relaxed if a CESA may be necessary! In fact, I refuse the risks.

Cheers!

I agree with you about redundancy and "instabuddies" maybe not trustworthy. Also about Spare Air being better than nothing. When diving really deep (100'?) I take my pony bottle and never dive alone. For my shallow solo shore diving (say that 3 times fast), it is a comfort to know I can do a CESA at any time. Then again, you can always wind up solo due to buddy separation.

 

[TMHeimer]

I’ve seen the video. I also talked with a guy who said he had to, as a result of his own carelessness, perform a CESA from 70 feet. Having just exhaled when he discovered he was out of air, he said he did not experience any benefit from air expanding in his lungs, but he did get one small extra breath on the way up as the air in his tank/reg/hose expanded enough to give one sip of air that he thinks made the difference in getting to the surface alive.

I mentioned as well not noticing expanding lung air. I imagine you just don't notice it because you're ascending without inhaling, so you are concentrating on that.