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OOA after only a few minutes with a full tank at 17m

Discussion in 'Basic Scuba Discussions' started by Roy_W, Aug 12, 2019.

  1. Firebar

    Firebar Angel Fish

    # of Dives: 25 - 49
    Location: UK
    Why to which part?

    We should be opening valves with a gentle finger hold to avoid mashing them into the stops and damaging things, see the photos of damaged o-rings that were posted by Miyaru.

    As to why I crack back a tiny bit, no real reason apart from it feels the right thing to do to me, rather than leaving it hard on the stop.
    The Chairman likes this.
  2. chillyinCanada

    chillyinCanada Solo Diver Staff Member

    When we vacation dive or dive off of a boat, where we may be helped a little or a lot by the crew, it behooves us to be pleasant.

    In that regard, it is easy enough to to be nice and still make your preferences known.

    I let the crew set up my tanks. Then I check my gear over from top to bottom to ensure everything to be clipped is clipped, buckles buckled, couplings coupled, weights where they should be etc. Often the tank band is not where I like it, so that gets moved. Then I check to make sure that my air/gas is on. I turn it all the way on. If crew is trying to get me to do the quarter turn back, I have a smiling chat with them, wherein I'll try to help them understand that was the old way, and that I prefer it turned fully on as in the new way. English is not always their first nor even their second language. Perhaps they just find me peculiar and that is alright with me.

    Then I fully check my regs and ensure they're properly connected everywhere. I inflate my bcd, I deflate it, then I check my purges/inflator and then I breath off of my regs and then I do the fast deep 3-4 breaths watching my spg. From that point forward, I do my best to make sure no one goes near my gear. If I'm sitting in front of it, I watch to ensure no one reaches across behind me. If they do and I can't see what they may have done, I check my air again.

    Assuming I'm doing a back roll, just before I roll, I do the 3 hard deep breaths again watching my spg.

    I do the same too if doing a giant stride.

    Eventually, the crew gets used to my "weird" ways.

    But now, I shall do another test. I'm going to try watching my spg as I breath off of it at different valve turn positions. I may even go in knowing that it's only partially open and see what happens as I descend. Not evey dive mind you, just as a test for verification of certain things that I've read in this thread.
    Saniflush, Doc, The Chairman and 2 others like this.
  3. Roy_W

    Roy_W Solo Diver

    # of Dives: 50 - 99
    Location: France / Switzerland
    This was exactly what we did after we understood my problem and it is very easy to do on the surface, open the valve until the needle no longers moves when breathing. It is extremely surprising to learn how little that valve needs to be open to achieve this situation.

    So after reading the very interesting discussions and answers on this thread I am now going to adhere to the "Fully Open" or "Fully Closed" method, no more 1/4 turns for me.
    I will speak to my instructors this evening and ask why they still teach the 1/4 turn as I have just now read on the CMAS site that they have not taught that technique for almost 10 years....

    The Take-Home-Message Always fully open the cylinder valve before you dive, and never turn it back until you are on the surface and out of the water at the end of the dive. Check before going in the water that your pressure gauge is not adversely affected by your breathing.
  4. stepfen

    stepfen Barracuda

    # of Dives: 200 - 499
    Location: Greece
    Yes it has happened to me once some time ago - crack open the valve when putting rig together to check for leaks etc. Breathing from regs felt normal.
    Then I "forgot" to open the valve all the way when I should have (just before donning) and "forgot" to check SPG while breathing pre-dive. Few minutes later at 5 or so meters deep I was not getting enough air out of my regulator - I could breath but with lot's of effort and obviously something was wrong. I look at my SPG and I noticed needle was going all the way down when I was breathing.

    Warning: Get your pop corns ready!
    First thing I did was to reach for my valve and turn it - half turn was enough to restore normal breathing - then signaled to buddy to turn it all the way - back then I couldn't do this comfortably. We finished the dive as normal and I explained to my buddy the whole story afterwards.
    I think it was the first time I did this for real (haven't drilled turning the valve before - just few times I tried to see if I could reach them).
    I wonder how come nobody has mentioned reaching/turning the valve yourself yet :) :popcorn:

    Now my predive procedures have changed A LOT. Valves are always either OPEN or CLOSED - nothing in between although I admit I turn the knob back but just a tiny bit so it won't feel "stuck". When on a boat, I check/open the valve myself just before donning my wing and if anybody from the crew tries to touch it afterwards I tell them it is open. I can tell by the amount of time they are touching it if they could switch it off accidentally (it takes few seconds of turning a fully open valve to close it). After this anyway I breath regs and inflate wing while watching SPG, I also check SPG early during decent.
    chillyinCanada likes this.
  5. chillyinCanada

    chillyinCanada Solo Diver Staff Member

    Yes as you say! I forgot to add that I do check the spg very early on, as well.
    Blueringocto_73 likes this.
  6. Roy_W

    Roy_W Solo Diver

    # of Dives: 50 - 99
    Location: France / Switzerland
    For the moment I only dive singles and the subject of reaching/turning valves had not yet cropped up in my training, I've only got 33 dives under my belt, CMAS 2 Star. So my first reaction was to simply signal OOA and then start a controlled ascent. I imagine that it will arrive when I start the CMAS 3 Star.
    chillyinCanada likes this.
  7. TeamBubbles

    TeamBubbles Angel Fish


    This. This right here is the whole reason Scubaboard should exist - to allow people who would otherwise not meet to share experiences, to work toward the development of best practices, and to implement them into their everyday diving and teaching. Well done, sir.
    Bagoose, rsingler and Roy_W like this.
  8. seeker242

    seeker242 DIR Practitioner

    # of Dives: 200 - 499
    Location: Pompano Beach, FL
    And the solution, to alleviate unnecessary confusion, is to get rid of the backing off altogether.
    Hoyden likes this.
  9. tursiops

    tursiops Marine Scientist and Master Instructor ScubaBoard Supporter

    # of Dives: 2,500 - 4,999
    Location: U.S. East Coast
    Nice article....it says at one point:
    I just looked at a PADI OW manual from 2008 (not the latest). It says: "When setting up your equipment, open the valve slowly all the way, until it stops turning. (Note: It used to be common to open the valve all the way, then close it a quarter to half a turn. This isn't necessary with modern valves, though it doesn't hurt anything if someone does it.)"
    RogueClimber, Dan and BlueTrin like this.
  10. Storker

    Storker Divemaster

    # of Dives: 100 - 199
    Location: close to a Hell which occasionally freezes over
    ...unless you're winter diving and your 2nd freezes and freeflows on the surface.

    Been there, done that. Several times. Never got a T-shirt, though. And the only way to stop that freeflow is to turn off the gas and wait until the reg has thawed. Drop the reg into the water to make it thaw faster.
    rsingler and The Chairman like this.

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