1. Scarecrow28
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    Scarecrow28 Contributing Member

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    Diving and Decompression

    Discussion in 'Research' started by Scarecrow28, Oct 17, 2008.

    When your diving, how deep do you have to dive in order to require taking decompression stops? Thanks in advance!
     
  2. Scarlett_156
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    Scarlett_156 Active Member

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    It depends on what type of equipment you are using. Look it up! yours in Chaos, Scarlett
     
  3. lordofhats
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    lordofhats Contributing Member

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    There are two things to loom out for here. Decompression Sickness, and Nitrogen Necrosis.

    Decompression Sickness is simply related to pressure (measured in bars for diving). About every 10 meter, a little over 33 feet, pressure increases by one bar the farther down you go. Now, going down isn't the problem, it's coming back up after being very deep or down for a long time. If you ascend to quickly in either case without stops, you risk not giving enough time for your body to adjust to the change in pressure, and this can present a wide range of problems from joint and muscle pain, to neurological problems!

    When I was in diving school I was told that for depth, the marker is generally 100 meters where decompression stops are absolutely necessary (they are recommended for depths over forty but a paced ascent speed is often enough to compensate), and for time the marker was 30 minutes past 10 meters. I was never told how long the stops were because the place that did the training didn't offer dives past 20 meters, and at that depth a normal steady ascent speed is enough to protect one's self form harm.

    Past 20 meters you hit the risk of Nitrogen Necrosis (Mostly harmless prior to 30 meters but I was told that you can feel a slight tenseness ascending from depths over 20 meters). This is caused by nitrogen dissolving into nerves and interrupting transmissions. This can effect one's mind and results in erratic and illogical behavior (it can be quite deadly for divers). I've been told that Nitrogen Necrosis is like being really, really, drunk in that it has the same effects on decision making and impulse control.

    These reason among others are why no experienced diver dives alone.
     
  4. Wreybies
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    Wreybies The Ops Pops Operations Manager Staff Contest Administrator Supporter Contributor

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    Dives as shallow as 30 meters can require stops. It depends much less on equipment used than on time spent at a given depth. When you get certified, you have to learn how to calculate that tables for decompression. How far down / how long spent down at that depth / how long you have to wait until you can make the next dive.
     
  5. MajorInkSpill
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    MajorInkSpill Member

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    I was trained to release the pressure every meter or so, to be safe. While descending, keep your eyes on your marker (it can be incredibly disorienting to descend...), and every meter or so, or maybe every foot, I plug my nose through my mask and breathe into it hard enough to make my ears pop. Don't do it too much, or you may damage your ears. Don't skimp out on it, or you may end up with one of the problems lordofhats described.

    Oh, and never never NEVER hold your breath while diving, unless you enjoy the ideas of your lungs exploding upon ascent.
     
  6. Scarlett_156
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    Scarlett_156 Active Member

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    If you are just diving with a snorkel mask, then you're limited by physiology--to a degree. Pearl divers can dive to incredible depths. It's a matter of training, pretty much like yoga. If you dive with equipment, you're limited by the equipment.
    Good advice there. xoxo
     
  7. Wreybies
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    Wreybies The Ops Pops Operations Manager Staff Contest Administrator Supporter Contributor

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    Here's a wiki-link with more links of commonly used decompression tables.

    Dive Tables
     
  8. Cogito
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    Cogito Former Mod, Retired Supporter Contributor

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    It's nitrogen narcosis, not necrosis - also called rapture of the deep. It's closely related to inhalation anaethesia used in medicine. You lose coordination, fine and gross motor control, judgement and the ability to concentrate. Divers have reported trying to hand off their air hose to passing fish.

    Depth, breathing misture, and the time you are at that depth all affect the decompression stops required. There are decompression tables you can look up, and I believe that you can also get dive compuers you bring down with you that will help you keep track of it.

    I don't scuba dive, although I've always been interested in it. I do snorkel dive, but decompression is not an issue snorkelling. You can't overpressurize your lungs snorkelling, because you only fill your lungs at surface pressure.

    But with scuba, you equalize pressure with the surrounding water whenever you inhale from the tank. Every 32 feet of depth is another atmosphere of pressure, and as you ascend, you have to release that extra pressure.
     
  9. Wreybies
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    Wreybies The Ops Pops Operations Manager Staff Contest Administrator Supporter Contributor

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    Here's another link that might be useful. I got certified with PADI. There are a few other organizations, but PADI is the largest in the U.S.

    PADI
     
  10. Scarecrow28
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    Scarecrow28 Contributing Member

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    Thanks everybody. I was writing a little story involving diving when I began to think about the books I'd read involving diving and noticed I'd neglected to take decompression into consideration. All the info everyones provided will help a lot.
     

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