Frequency of advanced divers practicing CESAs ? [Poll]

[lowviz]

I certainly agree with @lowvis . the diving guru of New Jersey and a student of Bob Cronkwright's demanding ACUC dive certification that a free assent or a CESA should be a component of a good through skin and SCUBA course.

Sam, I'm a one bander.

No guru of anything and no student of Cronkwright(???) Huh???. I'm just an inlet diver who has no plans of dying underwater under any circumstance.

 

[Darnold9999]

My first set of equipment was a single 72 with a J valve and no SPG. Diving here Vancouver Island, diving in kelp is pretty common and the stupid J valve would get pulled pretty regularly. So much so that I had an ingrained habit for years of reaching back to check it pretty regularly throughout a dive - even after the J valve was no longer there. In any event it was also pretty common to reach back to pull the lever when you ran out of air and find that it was already pulled. Not an emergency, you just surfaced, breathing out all the way. Understand that mentally you were somewhat prepared for the J valve to not function so not quite the same as unexpectedly running out of air, however it did develop a confidence in your ability to get to the surface with no air. Said confidence is still there many years later. I know it is easy from pretty much any recreational depth, because I have done it several times. Don't really feel the need to practice it now, for all the reasons stated.

Part of the confidence for all of this is something Sam mentioned. I am really comfortable in the water without a tank. Swimming down to 60 feet to look around and then come back to the surface was something I was doing long before I got certified. This means that I am unlikely to panic at depth just because I have no air. Lots of other things might generate panic, but no air with a clear path to the surface is not one of them.

I think not teaching CESA is a mistake. I hear all the reasons re instructor harm, but I don't care how much you drill buddy stuff and gas planning someone not comfortable in the water is going to head for the closest source of air when it hits the fan and in the real world at least some divers will not be close to their buddy at all times. Doing it even once gives you actual knowledge that it is possible and not as difficult as you would think - might push panic a few seconds into the future.

 

[The Chairman]

someone not comfortable in the water is going to head for the closest source of air

Why are they even certified?

 

[aquacat8]

Free diving will teach you a few relevant things:
1) To move calmly and smoothly so you don’t use more oxygen needlessly.
2) If your diaphragm spasms it doesn’t mean you’re drowning, you can still go some more. To quote Monty Python: you’re not dead yet!
3) Control what you are thinking because thinking takes oxygen. If you get excited underwater when you’re free diving suddenly your brain uses more oxygen. You can feel this. It is good to have practice keeping the mellow free diver mentality.
4) How to do proper recovery breaths so you don’t black out on the surface once you get there.
5) Just the feeling of I’ve been here before, this far underwater without a tank.
6) There are a couple tricky differences: the first thing is of course that you must not hold your breath doing a CESA, but as a freediver you are used to it, the second thing is that your scuba gear is going to cause a lot more drag, the third thing is you really should not ascend as quickly as you are accustomed to as a free diver.

 

[aquacat8]

I have a question that may be relevant to the CESA being more dangerous than a normal ascent at the same rate: If you are not breathing in are you actually off gassing? Is the inhale required for offgassing to take place?

 

[aquacat8]

I sort of doubt in a real emergency situation that many people would be ascending at the slow scuba rate.

 

[TMHeimer]

Why are they even certified?

Agree with that, having seen some rather "curious" looking divers. I think we all have a point when panic will set in, but with more experience there could be more seconds of clear thought.
--Also agree withaquacat8 that many would CESA too fast in a real emergency. Hopefully, experienced divers would not.
We must remember we are responding to the OP's poll about correctly performed CESAs by experienced divers.
--aquacat8 asks a good question about offgassing when only exhaling. My guess is it would be similar to ascending while inhaling and exhaling. Someone better with the physiology of it maybe could answer. Perhaps this comes into play if someone dives to 100', ascends to 30' and finishes with a CESA--this situation means a lot more to off gas than if on a 30' dive all along.

 

[The Chairman]

I have a question that may be relevant to the CESA being more dangerous than a normal ascent at the same rate: If you are not breathing in are you actually off gassing? Is the inhale required for offgassing to take place?

No. Off gassing occurs when the tension (difference in gas & vapor pressures) becomes negative. This happens between tissues as well as in the lungs. As you ascend and exhale, all gas pressures in your lungs drops precipitously allowing nitrogen to continue to exit your blood stream. The greater the tension, the faster the off gassing.

I sort of doubt in a real emergency situation that many people would be ascending at the slow scuba rate.

Ain't that the truth. These are so easy to avoid. It's all about the situational awareness, and that includes your and your buddy's SPG readings.

but with more experience there could be more seconds of clear thought.

It's not so much a matter of "experience" as it is competence. There is a common lie that it takes a 100 dives to get buoyancy down. Not if you're taught right. Not if you're taught right.

 

[Kharon]

... There is a common lie that it takes a 100 dives to get buoyancy down. Not if you're taught right. Not if you're taught right.

Taught right and given the time & practice to get it down.

Didn't get that in my class, or anyway, I didn't get it down. Kind of hard to do when seriously overweighted and shallow. To be fair to my instructor, he passed off the OW section to an arrogant prick because he was talked into needing a break from classes. I fault him for passing off the checkout dives but not the overweighting.

Didn't take me 100 dives to get buoyancy down. Just some time in the water at 15' with near empty tanks and (self made) weights from 0.5 to 3 pounds in half pound increments.. Same with trim, time uinderwater trying different configurations. Though that took a bit more fooling around to get perfect.

One thing I think is important is re-checking weight every time your kit or body weight changes. I had to make a spreadsheet with base numbers as I dive both steel and aluminum tanks of different capacities and different configurations of insulation depending on season and how many thermoclines I'll hit.

By minimizing the amount of neoprene I need I've been able to cut my weight down so that it's the same in cold fresh water with insulation as it is in salt water with no insulation. That helps, but I still do a careful weight check at the end of my checkout dive. I bring two 0.5 and two 1 pound weights with me. A bit OCD. lol

 

[The Chairman]

Taught right and given the time & practice to get it down.

If you're taught right, it doesn't really take that much time. Many instructors hope that you'll figure a lot of this trim and buoyancy stuff out on your own. They don't really understand the physics that govern trim and buoyancy, so they don't (can't?) teach it. All skills are important and trim/buoyancy is every bit as important as being able to find your reg. In fact, proper trim makes it so, so, so much easier to teach and do this skill. Trim and buoyancy need to be one of the first skills introduced and then all the other skills are done while being neutrally horizontal. I remember the divers of the sixties, seventies, eighties and nineties. Their trim and buoyancy also sucked. It did. The guy who sold me my first pair of Jets in 1969, told me I could kick the crap out of the reef and not hurt the fin. Yah. Rly.