CESA theory

[tursiops]

what I did not have for my calculation was the residual volume

Because you were too damn lazy (or superior) to look it up.

 

[Blackcrusader]

Is this whole thing true or should you be prepared to die if you can’t reach the surface with whatever air you already have in your body? I am not talking about OOA due to lack of air in the cylinder but more a 1st stage failure. Thank you.

My whole premise is that you wrote this "Let’s assume that there is no other solution than CESA." If you assume this then you will die when there was no reason to.

By limiting your thinking that only a CESA is available when you have a tank with gas in it shows you have a limited perspective and we are trying to show you that there are other options and broaden your horizons. For me the last option is thinking about what residual volume of gas I have left in my lungs rather than how can I reach the surface and not die. Why are you not thinking how can I use the gas in my tank to get me to the surface and also use some of it for breathing. As you wrote not an OOA from an empty tank.

DM's are like any other diver, are either a benefit or a hazard.

 

[Dody]

Ok.

Dody I did not answer the entire thread. The entire thread was not about gas volumes for your CESA. The thread you started never mentions that in your first post. You were concerned about being able to exhale on the ascent. I think you meant 90 seconds not minutes though.

No way would I be able to exhale during 90 minutes starting with my lungs empty

I believe I gave simple answers without being technical about gas volumes for your cesa and I do not recommend doing one. There are other options. If one wants to have some self reflection about being experienced then you need to ask yourself if you really think you got properly trained for the certifications you hold.

DM certified divers should already know the things you are asking. Rescue divers should know this. AOW should know this. That is what others alluded to. Now as to not knowing about rebreathing from a BCD I can understand as it is not taught. In all your training about a failed first stage did nobody cover that there is still air in the tank to be put to good use? After all you are an expert in pipes. tanks. valves, pressures, volumes, gases, and physics outside of diving.

I can't do your physics but I can keep myself from drowning if I lost a first stage and had no buddy close by to assist. At the and of the day that is all that is required. Don't get distracted by some comments. You asked and are learning there is more than one way to get to the surface and keep yourself alive.

Now for CO2 accumulation I wrote on how you can test yourself on that. Get a large plastic bag and put it over your head and seal it as much and possible and rebreathe the air, you need to feel how to control the urge to breathe and make that air last a couple of minutes. It's not hard and it allows you enough time from 30m to get to the surface. If you want you can do a normal exhale and try to calculate how much residual air is still in your lungs as people do not expel all the air under normal breathing.

I don't care about how much volume of air I may or may not have if I need to get to the surface as I would not be wasting time trying to calculate it in the first place. Do you think oh **** first stage failure let me calculate how much gas I have in my lungs at 30m depth? I don't think so.

Ok. Maybe I expressed myself poorly. I know there are other proactive and reactive ways. I know that the rules are: do not do a CESA at this depth. I know what a regular DM has been taught in those conditions.
I was just trying to have a scientific approach to a what if situation. A different approach. To further possibilities. You know I read a lot and I have never seen it approached like that. And I always look for numbered data that I can understand to rules that are just « taught » .
My bad.

 

[Dody]

Because you were too damn lazy (or superior) to look it up.

Read the end of the thread before commenting.

 

[Dody]

That is not a realistic scenario. If you think that’s a realistic scenario you shouldn’t do the dive.

I don’t think about cesa and do never train for a cesa ascent.

Thanks for your answer. I may be a lousy diver as some here think but this is a question that has bugged me for weeks. It should not happen if you do everything right but what if it does anyway? I was trying to make a scientific analysis of CESA and I know there are alternatives.

 

[Blackcrusader]

Ok. I know what a regular DM has been taught in those conditions. I may be a lousy diver as some here think

OK nobody accused you of being a lousy diver. People do question did you rush through getting certifications as fast as possible that have left you underprepared and not properly trained by your instructors. From your posts about your diving adventures I would say that is a fair question to consider. When the xxxx hits the fan your certifications mean nothing. Your being able to react and get yourself out of a situation with no dive buddy nearby does. Like knowingly being underweighted and then being stuck to an overhead as your dive guide and dive buddy left you behind. Not knowing when to call and end to a dive or not even to start a dive. You are a DM and still cannot figure this out and scold yourself for doing dives cause someone said you are a rescue diver you can handle it even though the un familiar equipment is not functioning as you think it should.

Yes people on forums can be harsh but as I wrote I'd rather see you here posting than knowing you had some tragic end to your life.

I like the post idea of wanting to have a better understanding of a CESA re lung volume and how you gas will expand as you ascend and CO2 buildup etc. I never think of doing a CESA so never thought about it. Unless I read this thread I still don't think about it. I never plan for first stage failures but I have experienced it. They are not the end of the world, more of a nuisance and inconvenience than a life threatening event at least as far as I have from my own personal experiences.

 

[BlueTrin]

As an anecdote, the guy in this incident did a CESA from 30m with a really fast ascent rate and did not have any issues (the article says he was in serious condition but that wasn’t the case)

Second diver airlifted to hospital in month

A diver has been taken to hospital in a serious condition in the second incident in a month at a lake diving site.

www.kentonline.co.uk

 

[tursiops]

Read the end of the thread before commenting.

I did. What was I supposed to see?

 

[Searcaigh]

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[Dody]

I did. What was I supposed to see?

That the residual gas (and you are right that I was sloppy) is not the only unknown factor in my quest. Now, you can also think that my quest is ludicrous. Take a number in the lane