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Breathing Pattern and Bouyancy Control

Discussion in 'Basic Scuba Discussions' started by chebel, May 11, 2005.

  1. chebel

    chebel Angel Fish

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    I just returned from a trip to Mexico where I was fortunate enough to dive a couple of the Cenotes (underground caverns). What a fabulous experience but a true test of bouyancy control. I had to wear a heavier suit and I'm not used to freshwater diving so getting everything under control was a bit of a challenge. I started to consider carefully my breathing pattern and I asked the DM on the trip about his.

    Generally when I dive, I tend to take quick breaths in then extend the exhale to the point where I'm almost always exhaling. The DM said he exhales quickly, then hesitates as long as possible before taking a long slow inhale. Obviosly his BC was better than mine so I'm wondering if I should change my pattern.

    Can some of you more experienced divers share you typical breathing pattern underwater? I'm also wondering if you vary your pattern significantly during a dive as necessary such as taking a deep breath to clear a high coral formation etc.?
     
  2. Kim

    Kim Here for my friends..... ScubaBoard Supporter

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    Well there are a lot more experienced divers than I, but I'll give it a shot! ;)

    First of all I establish my bouyancy at a half filled lungfull of air. What this means is that if I inhale - I start to go up a little, and if I exhale I'll sink a little. Then I try to establish a sine wave pattern of in and out around that (you know a sine wave - those wavy lines along a central line in the middle?) I try to make both the inhale phase and the exhale phase equal - counting it out helps me there - for me a count of 4 in and 4 out works quite well, but everyone is probably a little different. Now if I see that I need to rise a little - say because I'm following a coral contour - then I'll shift the center slightly upwards, i.e take a slightly deeper breath and breath slightly shallower out. If I need to drop a little then I'll breath completely out and slightly less than a full lung in.
    If I really need to change my depth faster than this (but only talking about a couple of meters up or down) I will add a slight, and I mean slight, pause at the top or bottom of the cycle as required.
    If I followed the pattern that this DM told you I'd probably sink too much myself. I'm not saying he's wrong, but I think which part of the breath cycle is your true neutral point comes into play here. Like I said - I like mine in the middle. It sounds like he likes his more towards his full exhale point. Possibly he uses slightly less weight on his belt because of this.
     
  3. ScubaFreak

    ScubaFreak Instructor, Scuba

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    Hi Chebel,

    I Breath the same all the time, if i wanna sink i stop finning, if I wanna go over a coral formation I swim over it, depending on how high, maybe add a burst of air to the BCD.

    Scubafreak
     
  4. Kim

    Kim Here for my friends..... ScubaBoard Supporter

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    That's interesting. I take a lot of pictures U/W so I am often not finning but just hanging. I'm using both hands on the camera and so I couldn't be messing with my BC to find neutral. Using my lungs for control seems much easier as I manage that hands free! ;)
     
  5. ScubaFreak

    ScubaFreak Instructor, Scuba

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    I hear ya Kim :D No better way to get perfect buoyancy than putting a camera in your hands- most photographers I see underwater have flawless buoyancy!
     
  6. Kim

    Kim Here for my friends..... ScubaBoard Supporter

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    Well I'm not sure about that.:D

    It IS hard to take pictures though if you can't stay reasonably still - that's true!
     
  7. knotical

    knotical perpetual student Staff Member

    # of Dives: 1,000 - 2,499
    Location: Ka'u
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    Well described, Kim. You’re better with words than I, but I’ll attempt to describe a variation that still allows a complete exhalation (which is good because you remove more CO2).

    Spend more time in either the more-inflated (if you want to rise) or less-inflated (if you want to sink) part of the “sine” wave.
    So, instead of shifting the sine wave center upwards or downwards, squeeze the upper or lower portions to make them smaller (shorter time).
    I’ll try an example: To rise, quickly inhale most of a lungful, then dawdle while you complete your inhalation and continue dawdling while you start your exhalation. After your exhalation is well started, complete it quickly and fully, don’t dawdle, and inhale again quickly. To descend, do the opposite.

    I’m sure there’s a better explanation around here somewhere.
    I need a white board to draw this, or a better command of descriptive English.

    In lieu of a white board:

    For those who can't picture a sine wave, they can be seen lots of places, including this URL’s drawing below the TV:
    http://imagers.gsfc.nasa.gov/ems/waves3.html
    This can represent normal breathing, showing: inhale, exhale, inhale, exhale.

    Finding a sine wave distorted to match what I’m trying to describe is harder.
    Here is one that comes moderately close:
    http://www.ifm.uni-hamburg.de/ers-sar/Sdata/oceanic/intwaves/intro/
    Go to Fig. 2 and look at the line labeled pycnocline, then imagine that all three of the downward excursions go down the same distance. Also, get rid of those flat spots at the tops of the curves (never hold your breath). This would represent a method of breathing to ascend. Turn it upside down to descend.

    Hopefully I didn't totally waste everyone's time.
     
  8. Jason B

    Jason B Loggerhead Turtle

    # of Dives: 500 - 999
    Location: NC
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    I'll add in that usually there is a delay. When I inhale, I don't usually start to rise until I start to exhale. The opposite is also true...I don't usually start to sink until the exhalation is complete and the next inhalation has begun. This pretty much keeps you at a steady depth.

    Jason
     
  9. Kriterian

    Kriterian Solo Diver

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    Yeesh, you're almost as hard to drive as an airplane! Thanks for the nicely detailed tips though.
     
  10. JMcD

    JMcD Instructor, Scuba

    # of Dives: 200 - 499
    Location: Ontario, Canada
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    New diver here - I'm Off for my open water dives June 4,5 -

    I have to say thank you Kim for this description! Very helpful in providing a mental picture of what I was trying to accomplish in my pool classes. Now I can't wait to get in the water and work on it.

    Chebel, Thanks for asking the question - I'm looking forward to reading other's responses!
     

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