CESA Training

[Darnold9999]

I would love to hear a real answer one day as to why this cesa thing even exists and it would be such a relief if this thread didn't

In prehistoric times you dove with a J valve and no SPG. If you dove in kelp at all it was common for the rod to get pulled and for you not to notice. When you found your reg breathing hard you reached back and pulled the rod to get your "reserve". If it was already pulled CESA was your next and only option. Reasonably common and no big deal as normally you had a good idea that you were near the end of the dive so were on your way up anyway and reasonably close to the surface. When I got back into diving about 15 years ago I still had the reflex to check for the J valve rod position for the first few dives. Same as when I dive in warm water, I have the reflex to touch my chest to add air to my dry suit to slow the initial descent

Have never run OOA unintentionally since having a SPG nor have I had to do a CESA, but having it in the tool kit makes me more comfortable. Also having lots of experience free diving to 60 feet + gives me a fair amount of confidence that the surface is within reach on any rec dive. Would add my voice to those suggesting the OP learn to free dive. Adds a level of comfort to know that you can swim a long way without breathing. Pushes panic a bit down the road which IMHO is worth doing. Would also add that on a liveaboard doing multiple dives a day I am FAR less comfortable about CESA than I would be on a single tank dive in my local water.

 

[The Chairman]

In a vertical CESA, once a diver begins ascending, the expanding air in the bcd and lungs and wetsuit cells make it easier to ascend to the point that the diver needs to bleed out air from the bcd in addition to exhaling so as not to ascend too quickly.

It depends on how you dive. I don't have any exposure protection and wear the precise amount of weight so I don't have any air in my BC. I have been known to dive without a bladder on my BC.

 

[Blackcrusader]

The obvious answer is that if you find yourself OOA at 30 meters with no buddy and no redundant air source, you do what you can to get to the surface.

I submit to you, however, two things:

First, whatever 30 meter CESA you’ve practiced, the actual emergency won’t be the same as your practice. You won’t start with a deliberately full breath, you won’t manage your ascent rate well, and you will be extremely lucky to reach the surface alive, unbent, with no water in your lungs, and without an embolism.

Second, there are very good reasons no training agency prescribes CESA’s from deeper than 10 meters. It is an inherently risky maneuver, intended to be resorted to only emergencies that divers are diligently trained to avoid. You need to know it’s there the same way a fighter pilot needs to know his seat can eject: he knows ejecting will probably bust him up a bit, but it increases his chance of surviving an imminent crash.

Practicing CESA from 30 meters just in case you put yourself in that emergency is akin to practicing jumping out of a third story window just in case you find yourself in a house fire without a ladder nearby.

I’m in the redundancy camp. I carry a pony that I’ve practiced with and know is sufficient to get me and a buddy to the surface safely.

CESA is not your only option. I started diving when the J valve was supposed to be used and yes sometimes people had the valve already open and had incidents.

We all wear redundancy in our BCD as well. I was taught this as an emergency last resort to exhale back into the BCD from the inflator hose and re-breathe the air in the BCD. If you have ever put a bag over your head you will understand you can re-breathe your own air for a little while and live. We can debate the merits of this but many divers have survived OAA from equipment failure doing this. IF you don't keep your BCD bladder clean that is on you

In early 2019 I was on a dive at 30m and a divers inflator hose assembly blew out of his BCD when he put air into his BCD. Well all that air rushed out and he was struggling to ascend. I swam to him put my dsmb onto his d ring and put some air in it and we did a nice slow controlled ascent to the surface. It was not OOA but that diver sure did use a lot of air when his BCD broke.
Back on the boat the diver explained he was about to try and ditch his weights. He said he never thought of using the dsmb as a lift bag but then again he hadn't brought his either lol

Sometimes there is more than an only option that can save your life in an extreme emergency. I've had free flows of regs, leaking seals, never a complete major malfunction myself but have seen others have them. One of my dive buddies tie came of his mouth piece and he exhaled his regulator came out and when he inhaled he took in some water. He rushed for my secondary and it was a close thing. His secondary had come off its clip and when he swept for it couldn't find it as the hose had gone around the back of his head.

Emergency Breathing from Your BCD: Undercurrent 06/2011

 

[TMHeimer]

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

Yes. My idea of starting a (10 meter...) CESA with maybe half a breath is that you may have that much when you notice your tank is starting to breathe heavy due to almost empty. Just a thought. Not gunna practice that of course.

 

[David Novo]

I will find myself the lightest, trimmest, easy to strip down (my life is a journey) pony bottle.

That would be the Spare Air.

@Dody calculate how much gas you would require to ascend safely during an emergency from the deepest depth that you are diving and get a pony that at least can take that amount of gas.

I am pretty sure a SpareAir will not be enough

P.S.: I would not get anything that can take less than 4L @ 200 bar.

 

[Dody]

Surface checks are not accurate. The correct amount of weight you need is determined by a nearly empty cylinder (500 psi or 50 bar), an empty BCD’/wing, (and if you are wearing a dry suit, one with only enough gas to keep you comfortable) at your safety stop. You then rise and fall with normal breathing. But you don’t sink or cork.

check your weighting at the end of dives to dial it in.

That's the way I used to do it. 3 kg and wetsuit. But then, I could not go down at the beginning of my dives. I definitely need 4.

 

[Dody]

@Dody calculate how much gas you would require to ascend safely during an emergency from the deepest depth that you are diving and get a pony that at least can take that amount of gas.

I am pretty sure a SpareAir will not be enough

P.S.: I would not get anything that can take less than 4L @ 200 bar.

From 40 m, a safe ascent would take 4 minutes. Let's take 5. My SAC in normal conditions is between 9 (fit) and 15 (tired) l/min. In a very stressful situation, even though I am cold as ice in stress , people told me that I should triple my SAC. Let's take 45. From 40 meters, let's be very conservative again. If I consider, for the sake of the science that I stay 1 minute at 40 meters, 1 minute at 30, 20, 10 and 2 minutes (to make it 5 minutes) between 10 and surface.I would consume 45*(5+4+3 +*2*2)= 720l. I would need a 3,6 liters pony. let's say 4 as you mentioned. What's the volume of a SpareAir? Anyway, I would need a pony that I can travel with meaning empty and take it apart before flight check in and fill it up the destination dive shop.

 

[Dody]

Would also add that on a liveaboard doing multiple dives a day I am FAR less comfortable about CESA than I would be on a single tank dive in my local water.

Why? Because of risk of DCS due to N2 accumulation or because of exhaustion?

 

[Edward3c]

What's the volume of a SpareAir? .

500ml so at 200bar you get 100Lt. Not going to get you very far. Your 1 min at 40m you could use over 200Lt.

 

[Edward3c]

Why? Because of risk of DCS due to N2 accumulation or because of exhaustion?

No the build up of micro bubbles.