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padi ow, why is CESA recommended to 9m?

Discussion in 'Basic Scuba' started by ballastbelly, Jun 27, 2014.

  1. diver 85

    diver 85 Solo Diver

    # of Dives: 1,000 - 2,499
    Location: SW Louisiana
    ....................................You should have watched 'the series' back in '85------I remember it well.........
  2. beanojones

    beanojones Solo Diver

    The Mahi I mentioned earlier is a boat in 95' of water. I did the first one from the top deck, and then worked my way down. It was the first thing I had to do for my DM course, be able to do a CESA from the deepest depth I was likely to guide people.

    I don't think a typical diver can do it slowly, exhaling continously, without practice. I could not, the first couple of times from 60 feet. Thus I think everyone should practice it, far more often than the typical skills that get suggested for practice (air sharing, no mask swimming)

    On the other hand, in the old days every one could though, they did not worry about ascent rate, nor do I think someone who is out of air should worry about ascent rate. So finding someone who can do it should be no harder than finding someone certfied in the old days when ditch and dons were part of OW certifications.

    On the other hand, with taking advantage of the drop in ambient and breathing from the 'empty' tank, and not worrying about ascent, I imagine a fair number of people can still do it, since there are a some number of people who run out of air and not that many that die from it, though most don't have to demonstrate it from any significant depth in training.

    ---------- Post added July 7th, 2014 at 10:16 AM ----------

    If fast ascents from 100' killed people, there'd be a ton of tourists dead every year, and all of us who dove before computers would also be dead. Stuck inflators, failure to be able to dump properly, lost weight belts, make lots of tourist divers pop from 70' feet.

    Breath hold ascents are deadly. Fast ascents are not good, but not deadly.
  3. flots am

    flots am Solo Diver

    # of Dives: I just don't log dives
    Location: Wherever you go in life, that's where you are.
    Not saying it's impossible, just that I wouldn't be doing one "just for practice"

    Also, "back in the old days" tanks were a smaller and exposure protection was thinner.

    Now, it's entirely possible that someone could stay down for an hour+, suck down a 120' tank, run out of air, then bolt for the surface like Free Willy with a thick wetsuit.

  4. boulderjohn

    boulderjohn Technical Instructor ScubaBoard Supporter

    # of Dives: 1,000 - 2,499
    Location: Boulder, CO
  5. dumpsterDiver

    dumpsterDiver Banned

    # of Dives: 2,500 - 4,999
    I asked if YOU had ever done a 3 minute CESA... I asked if anyone has a video of a normal scuba diver doing any CESA for 3 minutes.
    Does anyone have that video? The key point here is 3 minutes. That is a loooong time to not exchange gas in your lungs..Yet your prior post made it sound trivial..

    I had to do a CESA from 60 ft when i got certified at 13 yrs old with the regulator out of my mouth in 40 degree water with 6 ft visibility. This was before BC's and it scared the hell out of me, but I did it.
  6. boulderjohn

    boulderjohn Technical Instructor ScubaBoard Supporter

    # of Dives: 1,000 - 2,499
    Location: Boulder, CO
    As taught by PADI (and really everyone when the concept was first invented), the "official" ascent rate for a CESA is 60 FPM. A CESA from 100 feet at that rate would take one minute and 40 seconds.

    When I took my instructor exam and we completed the CESA work, the examiner emphasized that the training standard for both the pool and the open water is for distance only, not time. If a student completed that distance going faster than 60 FPM, that was acceptable. We could not accept a panicked sprint, but faster than 60 FPM was clearly acceptable and up to our judgment. I have never attempted a CESA from 100 feet, but if I did, I suspect I would reach the surface in the neighborhood of 1:15.

    I believe anyone doing a real CESA from that depth while OOA will be going a lot faster than 30 FPM. I know I would.
  7. captain

    captain Captain

  8. dumpsterDiver

    dumpsterDiver Banned

    # of Dives: 2,500 - 4,999

    Yes... 25 years ago (in freshwater springs) I used to do multiple ditch and don practices leaving my scuba tank at the bottom in 60 feet and then swimming slowly up, resting on the surface and then swimming back down to my tank. I am sure I can still do that with little stress.

    My question was very specific about the reference to 3 minute duration CESA's. It is possible to survive a very rapid CESA with only an exhalation, but it surprises me when people talk about swimming for 3 minutes with no gas exchange as if it were a formality.
  9. pdhenry

    pdhenry Contributor

    # of Dives: 25 - 49
    Location: Pennsylvania
    I was assuming they had used a Steinke hood but that wasn't invented until 1961. Possibly they used a Momsen lung.
  10. iztok

    iztok PADI Pro

    # of Dives: 200 - 499
    Location: Charlotte, NC
    Not quite the same. If I remember correctly, submarines are not pressurized to the ambient pressure.

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