I practiced today starting at just 20'. Took a full breath in, put my comp in front of my eyes and said "ahh" and went up. I was going up a little to fast tho around from like 14-8ft. I was a little buoyant starting with a full lung. Also, I was letting the air out a little to fast as a result. I might start with half a lung next time? What say this counsel?
Lack of oxygen during a free ascent?
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What is NECESSARY is to keep an open airway, so that expanding gas can escape. If you are very familiar with the difference between a closed and open glottis, you can simply maintain the latter state. Since most people aren't used to making that distinction, we teach folks to hum or "ahh", because if they are using air to make a sound, they HAVE to keep the glottis open.
Stating it a little more directly than TSand M, YES, unless you want to kill yourself -- at this point in your skills development anyway -- too dramatic?
You probably have much more than 50% of your maximum lung volume when you estimate 50%. Gas expansion in the last 20' is waaay too close to 2x at 33' to stake your life on!
It is absolutely necessary to avoid any excess pressure buildup in your air filled cavities, especially the lungs. Alveoli are like one cell thick... kind'a delicate. For all practical purposes, lungs don't have nerve endings that will tell you things are getting a little stretched in there. As you practice, you will discover exhaling is the result of keeping your airway open on ascent, not forcefully blow gas out. Until then, consciously exhale.
Besides, that misses one of the most important points of the skill. You want exhaling on ascent to become an automatic reflex regardless of the situation, not just on free ascents.
You might find these comments useful: http://www.scubaboard.com/forums/solo-divers/384706-solo-diving-checklist-musts.html#post5921772
I suggest you use one hand for your second stage and the other to vent your BC. You can get a sense of ascent rate while breathing normally on ascent. IMHO, you should be exceeding 30/Min by at least 2x. That is why you want to make deeper practice runs first during a days diving.
This is my priority, in this order, when circumstances force selecting between bad options:
1: avoid drowning
2: avoid any flavor or barotrauma
3: avoid decompression illness
Obviously, avoiding situations that require dealing with the choice is the objective. I just dont want to waste valuable time debating the choices when it comes to that.
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I think there was 100' of water, but that is off the top of my head. They tore it down in the 1990s. It was almost 65 years old and I am surprised they could control the rust that long.
A lot of diving pioneers were stationed there including Capt. George Bond and Bob Croft. Most of these heavy-gear divers became very competent freedivers. Croft was the first man to freedive deeper than 200' in 1967 the guy had a 9½ Liter lung capacity.
windapp
Contributor
Correct me if I am wrong, but aren't you supposed to keep your regulator in you mouth during a CESA? I was taught that in most cases, there will be one more breath available from your tank as you accend.
Also, my understanding is that the ideal way to do a CESA would be to hold your breath using only your diaphram but we do the ahhh(in my case a falseto eeee) because it is very difficult to keep your airway open under relaxed circumstances and impossible in an emergency.
Also, my understanding is that the ideal way to do a CESA would be to hold your breath using only your diaphram but we do the ahhh(in my case a falseto eeee) because it is very difficult to keep your airway open under relaxed circumstances and impossible in an emergency.
CESAs are a subset of the broad category of free ascents. My understanding from divers who taught at the Navys submarine escape towers, circa 1960s, was that lips were far less of a problem for submarine candidates to open than the all the mussels and tissues at the back of the throat. Keep in mind; these guys were heavily indoctrinated to maintain an open airway so it may not apply equally to casual recreational divers.
Opening my airway has become such a reflex that closing lips while in the position feels really odd or uncomfortable.
Opening my airway has become such a reflex that closing lips while in the position feels really odd or uncomfortable.
Hank49
Contributor
CO2 tells the brain but only to a point....I think. An abundance of oxygen in the blood may actually override that urge.
One day I was bored because the weather sucked and I couldn't go out to the reef, so I was "breathing up" off an 02 bottle we have in the hatchery.
I did about 6 or 8 deep breaths of pure o2 and held my breath while lying on my back resting. After about 6 minutes (I can do 4 minutes on air) my diaphragm began to gently spasm, I guess because of the CO2 buildup. It was involuntary and very regular. I DIDN'T, however, feel the need to breath. At 6 min 45 seconds, I figured I should stop because of the spasming but felt I could have gone on to at least 8 minutes.
Perhaps I would have passed out because of the CO2 also, Not sure. I don't recommend anyone trying this.
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