He'd drilled that into my head (about taking or trying to take another breath as you go) so much so that 2 decades + later, it's still first in my mind, that I might be able to get another breath or two as I ascend.
I confess that I had a hard time with this concept when it was first introduced to me. So, some years ago, I decided to test it. I took a 40cf pony, with about 500 psi left in it, down to 93 feet and sucked it dry - I was sucking on a vacuum when I switched back to my primary. On my primary gas supply, I then ascended to a platform at 15ft and switched back to the pony, and got 3+ good breaths from the regulator second stage (3 normal breaths and a partial 4th). That was with a 40 inch hose on the second stage of the pony. With a 7ft hose, maybe the results would have been even better.
Jcp2:
Can a diver practice a voluntary CESA safely? Who would be around to help if something goes wrong? An instructor?
Yes, you can practice it safely. And, you don't need an instructor to do so. A dive buddy - yes. One of the unfortunate aspects of dive training is that THE MAJORITY of certified divers
never practice the skills they supposedly 'mastered', again after certification. A number of SB members are exceptions to this, fortunately. But, the reality is that we see Accident and Incident reports where divers come to grief because they aren't able to do something as simple as orally inflating their BCD, or dropping their weights. And, these are easier skills to practice, and perform, than a CESA. This is not a criticism of training, or agencies. Rather, it is an honest acknowledgement that the conspicuous relative safety of diving lulls many divers into a sense of security that may not serve them well in the unlikely event of a gear failure, or out of air emergency.
If the DAN data are to be believed (and I certainly think they should be) a substantial proportion of reported recreational diver injuries and deaths occur in connection with some failure of the gas supply (and 'failure' is a euphemism for 'running out of gas' in many if not most cases). So, action directed toward correcting problems that involve interruptions of the gas supply should be a priority - preventing it from happening in the first place, AND managing it when it occurs. That management should include recurrent training to make the execution of emergency procedures as competent, timely and flawless as possible. Practicing a CESA can be part of the management process.
Yes, it is (far, far) better to not find yourself in a position where executing a CESA is your best option - engaging in competent dive planning, equipment maintenance, buddy skills development, redundancy, etc., are ALL better uses of time than practicing a CESA, at least from an intellectual perspective. Personally, I like the idea of having the ability to competently execute a CESA in my array of management procedures, even though I should never have to get to that point. My personal reservations about the CESA have to do with the toll it takes on me as an Instructor. I have never had a student injured while performing a CESA as part of their training, in Confined or Open Water. But, I have had more than a little ear discomfort, even damage, from making multiple ascents (and subsequent descents) with students as their Instructor. So, if PADI were to remove the CESA from the list of skills that are taught in Open Water Diver training, I wouldn't be too sorry. But, I would personally still practice it, just in case.
