Recreational Pony Bottles, completely unnecessary? Why or why not?

[BlueTrin]

Sometimes people bite off more than they can chew and make a run for the surface. But when they get there it’s embarrassing and “my reg stopped working or I had trouble with gear” saves face. Not saying that’s what happened but who knows without a gear check.

I don’t know, he sent the regs for checking and spent a bit of time trying to find the root issue.

The cylinder was a rental and someone mentioned it could have debris. The regulator was new.

It’s possible he lied but I couldn’t tell either way in this case and his behaviour does not seem to match someone who would just cover for ego.

 

[Celt]

I don’t know, he sent the regs for checking and spent a bit of time trying to find the root issue.

The cylinder was a rental and someone mentioned it could have debris. The regulator was new.

It’s possible he lied but I couldn’t tell either way in this case and his behaviour does not seem to match someone who would just cover for ego.

Who knows and without a proper investigation these incidents never get solved.

 

[undrwater]

I cannot possibly estimate how many threads on CESA I have read in my 17+ years on ScubaBoard. The overwhelming majority of posts in those threads convey the following beliefs:

1. I can't possibly do a CESA from more than 20-30 feet because I can't hold my breath any longer than the amount of time it takes to go that far.
2. If I suddenly go out of air after an exhale, I can't possibly make it from any depth.

A joint PADI/DAN study about 8 (???) years ago found that the number one training-related cause of diving fatalities was an air embolism following a panicked, rapid ascent to the surface, probably because the diver held his or her breath while ascending. I will venture to say that those people almost certainly held those mistaken beliefs, which in turn led to them holding their breath.

I like the turn this discussion has taken. Can you or @Bob DBF discuss the differentiation between a scuba CESA and a submariner CESA? It seems there is one.

Also, can someone explain the sensation one feels when doing a CESA from 90+fsw? I did an accidental emergency accent once when I was learning to use my dry suit. That was from 20', and I can't recall if I ever inhaled (I had gas), but I know I was trying not to.

 

[boulderjohn]

I like the turn this discussion has taken. Can you or @Bob DBF discuss the differentiation between a scuba CESA and a submariner CESA? It seems there is one.

Modern submarine ascents usually involve specialized suits, but they were previously done without them. They are actually what most dive agencies would call a buoyant ascent rather than a CESA, but the difference is minor. The difference between a CESA and a buoyant ascent is primarily speed. In a CESA, the diver ascends at a controlled rate of speed (that's the C in CESA), not much more than would be done normally. In a buoyant ascent, the diver inflates and/or drops weights in order to make a more rapid ascent. Buoyant ascents are recommended for deeper depths. You can turn a CESA into a buoyant ascent at any point in the ascent.

Here is a modern video showing two ascents in a naval training tower. The second uses a specialized suit. The first uses a simple flotation device. Note the amount of air being released through the mouth.

This a more vintage video (1958) from the days when this method of submarine escape was first used by the US Navy. I like this video better because the trainees are using almost no gear, and the video shows every step, starting with the initial HUGE exhalation.

The things to notice are how much air is expelled before the ascent begins, and how much air is still available for exhalation after that.

This contrasts mightily with horizontal CESA training, in which there is little to no air expansion, and the ability of the student to complete the exercise depends upon the ability to start with full lungs and continue with only the teensiest amount of exhalation--much like holding one's breath. This exercise gives students a completely incorrect concept of what a real emergency ascent, whether CESA or buoyant ascent, is really like. Most importantly, it gives them the mistaken notion that they can only do it from the shallowest of depths.

In contrast, the 1958 film says that the British navy had done these ascents from more than 300 feet. I have only met a few people who have done true CESAs from depths greater than 75 feet, and each told me that once they started to exhale, there was no stopping it until they reached the surface.

 

[jborg]

Also, can someone explain the sensation one feels when doing a CESA from 90+fsw? I did an accidental emergency accent once when I was learning to use my dry suit. That was from 20', and I can't recall if I ever inhaled (I had gas), but I know I was trying not to.

I corked from about 25m earlier this spring, for a combo of stupid reasons (instabuddy miscommunication, unfamiliar equipment, unfamiliar conditions, and poor judgement). I was intensely stressed during the ~minute it took to surface and realizing the danger exhaled very forcefully; enough so that I remember that I felt I had to take a breath on the way up, but a very small one followed by more exhalation. That was certainly more of a stress reaction than an effect of actually needing air. Not really a CESA, what with totally lacking the C aspect of it...

(This was also a memorable dive because the corking resulted in me being back on the boat early and being available to help rescue an unconscious RB diver who popped up shortly afterwards... This was not a great day, but at least my mishap is not what the rest of the dive group remembers.)

 

[tursiops]

Modern submarine ascents usually involve specialized suits, but they were previously done without them. They are actually what most dive agencies would call a buoyant ascent rather than a CESA, but the difference is minor. The difference between a CESA and a buoyant ascent is primarily speed. In a CESA, the diver ascends at a controlled rate of speed (that's the C in CESA), not much more than would be done normally. In a buoyant ascent, the diver inflates and/or drops weights in order to make a more rapid ascent. Buoyant ascents are recommended for deeper depths. You can turn a CESA into a buoyant ascent at any point in the ascent.

Here is a modern video showing two ascents in a naval training tower. The second uses a specialized suit. The first uses a simple flotation device. Note the amount of air being released through the mouth.

This a more vintage video (1958) from the days when this method of submarine escape was first used by the US Navy. I like this video better because the trainees are using almost no gear, and the video shows every step, starting with the initial HUGE exhalation.

The things to notice are how much air is expelled before the ascent begins, and how much air is still available for exhalation after that.

This contrasts mightily with horizontal CESA training, in which there is little to no air expansion, and the ability of the student to complete the exercise depends upon the ability to start with full lungs and continue with only the teensiest amount of exhalation--much like holding one's breath. This exercise gives students a completely incorrect concept of what a real emergency ascent, whether CESA or buoyant ascent, is really like. Most importantly, it gives them the mistaken notion that they can only do it from the shallowest of depths.

In contrast, the 1958 film says that the British navy had done these ascents from more than 300 feet. I have only met a few people who have done true CESAs from depths greater than 75 feet, and each told me that once they started to exhale, there was no stopping it until they reached the surface.

Reemphasizing that the C in CESA stands for Controlled...meaning no more than 60 ft/min ascent speed. If one is buoyant, and getting more buoyant as you go up, the speed can easily exceed that, by a LOT, so dropping weights in order to ascend is a last resort.
In fact, historically, PADI OW training gave five ways to ascend: Normally, with an Alternate Air source, CESA, Buddy-breathing (one regulator, shared), and Buoyant. In 1994 PADI stopped teaching buddy-breathing except as an optional skill, and in 2009 dropped it from the curriculum. So now there are just four way to get to the surface, and Buoyant is last choice exactly because it is NOT Controlled. Both the NOAA and US Navy Dive Manuals contain warnings about buoyant emergency ascents, suggesting they are a "last resort."

 

[grf88]

Reemphasizing that the C in CESA stands for Controlled...meaning no more than 60 ft/min ascent speed. If one is buoyant, and getting more buoyant as you go up, the speed can easily exceed that, by a LOT, so dropping weights in order to ascend is a last resort.
In fact, historically, PADI OW training gave five ways to ascend: Normally, with an Alternate Air source, CESA, Buddy-breathing (one regulator, shared), and Buoyant. In 1994 PADI stopped teaching buddy-breathing except as an optional skill, and in 2009 dropped it from the curriculum. So now there are just four way to get to the surface, and Buoyant is last choice exactly because it is NOT Controlled. Both the NOAA and US Navy Dive Manuals contain warnings about buoyant emergency ascents, suggesting they are a "last resort."

With heavy exposure protection a controlled ascent can quickly become an uncontrolled ascent. A CESA should be the last resort.

 

[boulderjohn]

Reemphasizing that the C in CESA stands for Controlled...meaning no more than 60 ft/min ascent speed.

When I took my Instructor Exam, we were told emphatically that although the language for the CESA used the word "normal" to describe the ascent speed (PADI was then still using 60 FPM), the actual standard was for distance, not time. We we were told to allow and even expect students to go faster than 60 FPM.

 

[tursiops]

With heavy exposure protection a controlled ascent can quickly become an uncontrolled ascent. A CESA should be the last resort.

No, it is the next-to-last resort. If it becomes uncontrolled (i.e., buoyant) then it is no longer controlled.

 

[tursiops]

When I took my Instructor Exam, we were told emphatically that although the language for the CESA used the word "normal" to describe the ascent speed (PADI was then still using 60 FPM), the actual standard was for distance, not time. We we were told to allow and even expect students to go faster than 60 FPM.

The IM says:
"Observe and maintain control during the ascent, not exceeding 18 metres/60 feet per minute."