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Performing a CESA After Exhale

Discussion in 'Solo Divers' started by certainmisuse, Mar 24, 2019.

  1. certainmisuse

    certainmisuse Nassau Grouper

    # of Dives: 100 - 199
    Location: Atlanta GA
    Perhaps this will ultimately be a silly thought, but it has crossed my mind enough to ask around. There are certainly scenarios for a solo diver -- or any diver really -- where a CESA is the only answer. I have always wondered however, what if the failure occurs at the very end of an exhale? Are you simply totally screwed with regard to needing to exhale throughout the accent? Am I missing something regarding the physics? Thanks.

  2. CuzzA

    CuzzA Solo Diver

    There will still be useable gas in your lungs which will be expanding as you ascend. The co2 build up will feel like hell on the way up. Don't hold your breath. :wink:
  3. Akimbo

    Akimbo Lift to Freedom Volunteer Staff Member ScubaBoard Supporter

    I did some testing on this decades ago. A normal exhalation is far from a full exhalation. You have plenty of Oxygen in your lungs, and especially in your hyper-Oxygenated tissues to sustain you for several minutes. Monitor your "normal" respiratory cycle and stop at the low end and hold your breath. Then exhale as much gas as you can, measuring it if you can -- exhaling through a hose into a graduated gallon jug inverted into a pool or deep sink for example. I found it is as much or more as my normal inhalation cycle.

    The challenge is to understand the difference between the rapid build-up of CO2 and the lack of Oxygen. You can't miss the symptoms of CO2 buildup but people can't sense hypoxia (short of blacking out). Freedivers that have learned to "push through" CO2 buildup are at considerable advantage in mastering CESA and free ascents. Once you get dialed in, your biggest problem with running OOA after an exhale will be the loss of buoyancy -- until the gas in your lungs expands as you get shallower.

    You might find this thread helpful: Max depth for CESA?, Post #40
  4. wetb4igetinthewater

    wetb4igetinthewater Instructor ScubaBoard Supporter

    # of Dives: 500 - 999
    Location: Seattle
    I think this is what mostly occurs in real life. Yes, you want to try to exhale continuously to ensure that your lungs don't stretch by 10% (that is my understanding of how much the lungs can stretch approximately before bursting). Keep in mind that you may try to take in a breath as you ascend. And you may be able to get in a little bit of gas. But as much as you can, try to exhale as you head to the surface.
  5. TMHeimer

    TMHeimer Divemaster

    # of Dives: 500 - 999
    Location: Dartmouth,NS,Canada(Eastern Passage-Atlantic)
    When I was assisting on OW courses students of course did the CESA starting with full lungs (instructor: "Take a deep breath and start up", etc.). After students were certified I did occasionally mention that it may be a good idea when practicing CESA to begin with half full lungs. If you can start up with full lungs you probably could begin ascending making a normal ascent. I even recall one instructor advising students to take THREE good breaths, which amounts to hyperventilating. I know full lungs means less chance of a student bolting in a panic. There is also the discussion of whether it is wise to practice CESA at all. I am in the camp of yes, especially if diving a lot solo.
    АлександрД likes this.
  6. happy-diver

    happy-diver Skindiver Just feelin it

    # of Dives: 2,500 - 4,999
    Location: same ocean as you
    Yeah with serviced gear with weekly tweaks and a full tank of fresh sweet gas
    I ain't done nor ever going to done no stinkin cesa
    diving is hard enough
  7. drk5036

    drk5036 ScubaBoard Supporter ScubaBoard Supporter

    # of Dives: 100 - 199
    Location: Sapporo, Japan
    I think people are missing his point. He’s not talking about running out of “Air” before reaching the surface, he’s talking about the requirement of exhaling during ascent to prevent an over-expansion injury.

    I’ll give a shot at the answer. If your lungs are truly empty, they can’t expand upon ascent, and therefore exhaling is unnecessary. In reality, some air will remain and can expand, and therefore upon ascent you should try to exhale as more gas “becomes available”. As someone else stated, the gas in your tank also expands, and you often get a breath there as well to help during ascent. I think this is why “blow and go” isn’t recommended; even if you think your lungs are empty, air can still expand resulting in over-expansion injuries.

    I’ve never done a “real” CESA from more than about 4 meters, so maybe I’m a little off base here and would like some verification of my answers.
    certainmisuse likes this.
  8. stepfen

    stepfen ScubaBoard Supporter ScubaBoard Supporter

    # of Dives: 200 - 499
    Location: Greece
    Any advice/recommendation about how CO2 buildup would feel during the ascent and how to overcome the fear of "lack of air"??

    I use to train/swim a lot back in the days and I could swim submerged horizontally with only goggles 30-40 meters (110ft or so) - but nowadays I guess not more than 10m/30ft. The feeling though about the CO2 built up or "lack of air" was totally different because I knew that at any moment I could just swim up a bit and access unlimited supply of fresh air if needed. When coming from the deep that's not true...

    I have free dived recently to 30ft/10m (with fins+mask only) and my reaction was to swim up as fast as possible towards the end which doesn't sound good idea.

    Any other suggestions???
  9. Sam Miller III

    Sam Miller III Scuba Legend Scuba Legend

    # of Dives: 5,000 - ∞
    Location: CALIFORNIA: Where recreational diving began!

    In the beginning in 1954 there was one certifying organization that was the very demanding LA Co UW Instructors Association who created the world's first certifying program, the Underwater Instructor's Certifying Course commonly referred to as "UICC"

    The course required a D&R at 33 plus feet and a free assent (aka CESA) from 100 feet.. Every one who passed the course performed a CSEA with out any problems.

    "Practice to perfection under controlled conditions what you may need to do under emergency panic conditions" was the theme

    In1967 LA County developed the world's first Advance Diver Program the three months long "ADP. " It require the student to perform a free assent a "CESA" from 33 feet.

    The program also required the students to maintain a LA Co dive log - the first time a dive log was required and it was the second dive log ever created-- The first Dive Log was created by the late Dick Bonin in 1955 while employed at thje Chicago based company Dive Master, and who later founded SCUBA Pro in 1963- Lets give credit were credit is do...

    Dick as an USN officer under Doug Fane { (read his book The Naked Warriors or view the movie - Underwater Warriors. Zale Parry (@Dr bill s close friend ) portrayed Doug's daughter) } In early 1950 Dick under the direction of Doug Fane were testing regulator performance under the artic ice for the USN Dick's regulator froze - he made a free assent under ice from 200 + feet..totally out of air

    Every diver I certified in 28 years of instruction as LA Co, NAUI, PADI CMAS and other certifications all did a 33 CSEA as part of Catalina dive experience. Not one had difficulty.

    While training and diving with my young son, what seems like in retrospect every day and night, I made a rule that he could only dive as deep as he could perform a free assent CESA. I rescinded the requirement at 66 feet -As an adult pre med student Sam IV and Jeff Bozanic were drilling 300 & 400 foot holes in the Pacific -Good training pays !

    Now he is practicing doctor and the director of the ER/Hyperbaric department at a local regional hospital

    I have made innumerable free assents CESAs from 100 and one from, GOK, how many feet ? when my regulator and lift bag became one and I was totally and positivity out of air ! So away I went all tangled and dangled blowing and going to the surface... And I am alive and replying to this thread

    Once perfected with perfect practice and even more practice CESAs should be an automatic reflex , so who knows ?

    I will always recall the LA Co motto "Blow and Go; Flair and you are There !" --

    I am going to the beach to walk my dog Lucky and not to attempt a CESA on the beach

    Sam Miller, 111
    aviator8 likes this.
  10. Norrm

    Norrm Banned

    Grab a lungful of whatever's left in your BCD.

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