Today's 136ft CESA trial

[dmaziuk]

So at less than 10 seconds to complete the 30 feet. We are supposed to fail students who go that fast.

It's not that easy to swim 6 times slower, that's a bit of a problem with horizontal swims.

And that's what I personally am not comfortable with: I know I can do 40 metres on a single breath of un-compressed air. What I don't know is if I can do it in 4 minutes, or even 2.

 

[boulderjohn]

It's not that easy to swim 6 times slower, that's a bit of a problem with horizontal swims.

And that's what I personally am not comfortable with: I know I can do 40 metres on a single breath of un-compressed air. What I don't know is if I can do it in 4 minutes, or even 2.

Why do you need to know if you can do it with uncompressed air? If you are at that depth, you will have been breathing compressed air. In a test situation, the CESA has been done at 300 feet.

 

[dmaziuk]

Why do you need to know if you can do it with uncompressed air? If you are at that depth, you will have been breathing compressed air. In a test situation, the CESA has been done at 300 feet.

It's not that I need to, I just do -- because in a horizontal swim you do it with uncompressed air, and I know how far I can swim that way. I can reasonably assume that coming up from that depth I will have enough air in my lungs, even if I start mostly empty, to last me at least as long.

Of course knowing that while swimming laps in a pool, and actually being in a CESA situation, are not necessarily one and the same.

 

[boulderjohn]

even if I start mostly empty,

This is a common question about the CESA--what if I start with my lungs empty?

The answer is that won't ever happen, because you never empty your lungs. I used to show this to my students. I would have them breathe in and out for a few normal breaths, and then I would tell them that at the end of the next breath, before they inhale, force themselves to exhale for as long as they can. They are all surprised by how much air was still in their lungs when they finished they had finished their breath and were about to inhale.

In addition, I have breathed stage bottles and other tanks down enough to be convinced that you will have enough warning through the difficulty of breathing the last few breaths to get at least some amount of inhalation before your ascent. I even have experienced this on the surface, because on days when I drive home over a mountain pass after a decompression dive, I breathe from my oxygen deco bottle before that ascent. I have finished it off a number of times, and I always know when it is getting near the end.

 

[dmaziuk]

This comes up in martial arts all the time: there's all these good reasons you can't train "for real", and with the way you can train, you can't help wondering if it'd be any use in real life if you ever needed it.

 

[Landlocked123]

That is impressive. Wont be trying that any time soon... but if you are diving that deep all the time its great to have one last trick in your bag if all else fails.

 

[northernone]

That is impressive. Wont be trying that any time soon... but if you are diving that deep all the time its great to have one last trick in your bag if all else fails.

It's wonderful for peace of mind to know how to hold calm and maintain focus even if everything goes wrong and you need back to the surface.

... Yes. I don't suggest people practicing it in the way I do. But in some form (perhaps how some agencies teach) it has good learning points that are valuable even if you have excessive gas redundancies and will never actually need to CESA.