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Frequency of advanced divers practicing CESAs ? [Poll]

Discussion in 'Advanced Scuba Discussions' started by Roger Hobden, Sep 27, 2018.

Approximately how often have you practiced doing CESAs up till now ?

  1. Never.

    119 vote(s)
    74.8%
  2. A few times.

    22 vote(s)
    13.8%
  3. About once every 5-10 years.

    2 vote(s)
    1.3%
  4. About once every 2-4 years.

    2 vote(s)
    1.3%
  5. About once a year.

    4 vote(s)
    2.5%
  6. About once every 5-6 months

    1 vote(s)
    0.6%
  7. About once every 3-4 months.

    1 vote(s)
    0.6%
  8. About once every 1-2 months.

    5 vote(s)
    3.1%
  9. More often then once a month.

    3 vote(s)
    1.9%
  1. Trace Malinowski

    Trace Malinowski Cave Instructor

    # of Dives: 5,000 - ∞
    Location: Alexandria Bay, NY
    2,325
    2,500
    113
    I currently teach reg in the mouth. I was addressing the OP that I, too, learned to jettison the reg in initial training 37 years ago and the thought process for it at the time.
     
  2. The Chairman

    The Chairman Chairman of the Board

    # of Dives: I just don't log dives
    Location: Cave Country!
    55,618
    22,826
    113
    It's all about limits. Before you dive, you should agree on both turn and thumb pressures. Turn pressure is half your gas less the thumb pressure. Thumb pressure is your depth x10 (imperial), with 600psi as an absolute limit. This is in addition to figuring out if you have enough gas to do the dive you want to do. Say my SAC is 0.8 and I want to dive to 100 ft.

    Thumb pressure: 100x10=1000psi
    Turn pressure (3000-1000)/2=1000psi

    These are my limits! I dive in such a way as to respect these limits.

    To get DAC is a bit more complicated, but it can tell you how long you can stay down. Say it's an 80 cf tank.

    [(99/3)+1] 0.8=3.2 Since, I'm can only use 2/3s of this tank, so I have 52 cf. 52/3.2=16.5 minutes. Rule of 120 tells me that I have @20 minutes at depth, so if I want to use all of my NDL, I need a bigger tank. This is for planning only. Use your PDC for your NDL and your SPG for your pressure limits (turn and thumb).
     
  3. KenGordon

    KenGordon Rebreather Pilot

    2,457
    1,199
    113
    My point is that the instructor givens them an ‘easy out’. If you believe a CESA is an option then you still have an option so can afford to be less diligent about the rest of it. If on the other hand the instructor tells you that if you run out of gas without an alternatively or a buddy you will very likely die then maybe the instructor is properly emphasising the need for awareness and so forth.

    Prevention, not cure. Especially if the cure is not very effective.
     
  4. The Chairman

    The Chairman Chairman of the Board

    # of Dives: I just don't log dives
    Location: Cave Country!
    55,618
    22,826
    113
    I understood your point and it has some merit. It's my opinion that an out of control diver is so preoccupied by trying to establish control that they neglect things like gas pressures and buddy whereabouts. Teach your diver proper trim and neutral buoyancy and they can easily track these two things. A diver who's plummeting, followed by an uncontrolled ascent, followed by another plunge is already so dangerously close to panicking that they don't have the mental resources to read their SPG much less keep track of their buddy. Imagine when this near hysterical diver actually runs out of air? His training has already failed him, so we can't expect him to resort to it now. Their near hysteria will instantly devolve into sheer panic and the diver is well on their way to injuring or killing themselves. The one or two CESAs they did in their OW class are the furthest thing from their mind. If you want to give a diver confidence: teach them trim and buoyancy. The best CESA is the one you avoid having to make. An ounce of this prevention is worth a ton of CESA cure.
     
    Kharon likes this.
  5. Bierstadt

    Bierstadt Barracuda

    # of Dives: 50 - 99
    Location: Erie, PA
    309
    206
    43
    My thinking is more that one will become more comfortable with the situation of having to rely on only the gas that is in one's lungs to reach the surface. Obviously if someone is unable to both learn freediving and remember to exhale while ascending after breathing SCUBA they ought not learn both. Or either, I imagine.
     
    Steelyeyes likes this.
  6. boulderjohn

    boulderjohn Technical Instructor ScubaBoard Supporter

    # of Dives: 1,000 - 2,499
    Location: Boulder, CO
    25,635
    17,069
    113
    If I aa relative of mine died after a panicked OOG ascent, and I found out you told them they had no safe option without an alternate air source and were going to die under those circumstances, you can you would lose that lawsuit big time.
     
  7. 2airishuman

    2airishuman Solo Diver

    # of Dives: 100 - 199
    Location: Greater Minnesota
    2,385
    1,593
    113
    John,

    I want to point out that the reg will only give you air if the OOA emergency was due to exhaustion of the air supply.

    If the OOA emergency was caused by a regulator failure or burst hose, or mouthpiece separating from the 2nd stage, or inability to find the 2nd stage with an arm sweep, or breathing from a pony cylinder instead of back gass, or any number of other things, then there will not be more gas upon ascent.

    Since the discussion here is regarding "advanced" divers, they are perhaps more likely to encounter an OOA emergency due to equipment failure, rather than a failure of gas planning.
     
  8. northernone

    northernone Great White Rest in Peace

    # of Dives: 1,000 - 2,499
    Location: Currently: Cozumel, from Canada
    3,793
    3,390
    113
    Gas planning is wonderful, also knowing you can calmly surface by slowly swimming does good things for maintaining calm and avoiding panic.

    When I can't directly surface that's when I want multiple other redundancies for breathing sources. In that case a tank strapped to another autonomous human isn't my first choice.

    Are we saying that a properly done CESA (as required by the training agencies) is too dangerous to be practiced by advanced divers to maintain master of this basic skill?

    (Video representing the calm required, begins a minute in. Though I prefer pants on my wetsuit and the r109 instead of the r108)

     
    aquacat8 likes this.
  9. Gareth J

    Gareth J Manta Ray

    # of Dives: 1,000 - 2,499
    Location: UK
    710
    564
    93
    I have dipped in and out of this thread as it has developed.

    I originally learnt through PADI, so did a CESA during my OW course. That is a long time ago now.
    After qualifying with PADI, I joined a BSAC branch. I have been trained by a number of agencies since. At some point in the in between years, I did complete the PADI DM course - but significant time has passed since I did that.

    Although learning in blue water with PADI, the vast majority of my diving is green water diving. I have always considered it viable to make a swimming ascent from 20m, single cylinder diving - which basically means No Stop Diving . Beyond this, some other independent gas source is wise. To 35m then a 3l (pony) is viable, Once you are into 30m, then you are probably going to incur a mandatory stop. Beyond this then a proper twinset is a minimum requirement.

    I think one of the issues for those of us not in the American environment, is that dives requiring mandatory decompression stops are still basically recreational. As such, a CESA ascent - from beyond 20m is not viewed as a sensible option. Certainly within BSAC, once we move much beyond 20m, the training materials heavily emphasis redundancy. Primarily a fully independent breathing source.
    The basic qualification, much like the basic PADI OW, is a 20m no stop dive qualification.
    The next qualification (Sports Diver), is a qualification allowing compulsory decompression stops, and a maximum depth of 35m.
    This probably colours Ken's view of CESA.
    One of the big drivers for independent breathing source is the environment in which we dive. Buddy diving is heavily emphasised within our training. It is often not practical, or even possible to dive in a group. So the American expectation of a DM supervising the divers is unrealistic. Visibility can be anything between 6 inches and 60 feet, unfortunately you may not know this until you actually descend. In addition, we expect extremely tidal water. So primarily, we expect best case scenario is that we will have assistance from our buddy, in the worst case, we are on our own.

    My MOD1 CCR training strongly recommend a fully independent bailout on any dive beyond 20m. (It was preferred that you carried a fully independent bailout for any dive.)
    It is a very long time since I dived in the UK with a single cylinder. On the rare occasions I have dived using a single cylinder, I have always had either a 3l pony, or a stage cylinder.
    I do dive blue water on a single cylinder, it may well include limited decompression. But single cylinder diving makes me extremely cautious.

    Carrying an independent gas source is so ingrained in me, that when some one asked if I found carrying a stage inconvenient, the statement seemed strange. It is no more inconvenient than the torch or camera I carry.
     
    Preach and northernone like this.
  10. 2airishuman

    2airishuman Solo Diver

    # of Dives: 100 - 199
    Location: Greater Minnesota
    2,385
    1,593
    113
    So, to the OP, no, I don't practice CESAs regularly. I performed one once when my mouthpiece came off at 15', when I did not have a secondary.

    Statistically, it's a numbers game.
    * What are the chances of being injured practicing a CESA?
    * What are the chances of a CESA being required in an actual emergency?
    * What are the chances of being injured in a CESA during an actual emergency, without recent CESA practice?
    * What are the chances of being injured in a CESA during an actual emergency, with recent CESA practice?

    I don't think confident, skilled divers, who are familiar with the concept of a CESA, will have trouble performing them, even without recent practice. Therefore, I think the hazard involved in practicing represents an added, unnecessary risk.
     
    Nirvana and Preach like this.

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