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What are the risks of many bounces between the surface and 15-20' / 5-7m of water?

Discussion in 'Basic Scuba Discussions' started by @dam, Jan 13, 2012.

  1. BCSGratefulDiver

    BCSGratefulDiver Mental toss flycoon ScubaBoard Supporter

    # of Dives: 2,500 - 4,999
    Location: On the Fun Side of Trump's Wall
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    I think you're more likely to develop ear issues than DCS issues with a lot of pressure changes in that range ... as long as you aren't holding your breath on ascent ...

    ... Bob (Grateful Diver)
     
    shoredivr and mselenaous like this.
  2. j yaeger

    j yaeger PADI Pro

    # of Dives:
    Location: Canton, New York, United States
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    bobs right on with the ears!!!!
    doing big classes for ow's after the morning class of cesa's, it's a challenge for sure in the afternoon!
    other than being exhausted by the students,no probs personally
    have fun
    yaeg
     
  3. fjpatrum

    fjpatrum Loggerhead Turtle

    # of Dives: 50 - 99
    Location: DC area
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    Am I missing something? At that shallow depth, you should be able to suck on a tank for at least a good 60-70 minutes even as a (reasonably comfortable) newbie diver. If you have a decent SAC and some experience, odds are you can get closer to 100 minutes on a single tank.

    What's to be gained by bounce diving it? I have no idea whether or not it would be safe, but I just don't see the point. If the diving is great at that depth, grab a second tank and do a second dive for another hour or two. If the diving's not that great, you'll still see something and you probably won't want to spend more than an hour or so in the water.
     
    Quero and ScubaSparky85 like this.
  4. TMHeimer

    TMHeimer Divemaster

    # of Dives: 500 - 999
    Location: Dartmouth,NS,Canada(Eastern Passage-Atlantic)
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    I do a lot of shallow diving near home. 10-30 feet, but no snorkelling (except surface use, of course). While I don't continually go up & down, I surface now and then to check location if the tidal current is strong. Ascend gradually, as always, never hold breath, and I doubt you'd have any problems. As pointed out, remember when on scuba and not snorkelling. My air lasts long enough, of course, that I either get tired of it or cold, etc. before getting low on air, so why even bother with snorlkelling?
     
  5. dumpsterDiver

    dumpsterDiver Banned

    # of Dives: 2,500 - 4,999
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    some would say.. for depths of 10-30 feet, why even bother with scuba gear?
     
    ScubaSparky85 and j yaeger like this.
  6. Diversauras

    Diversauras NAUI Instructor

    # of Dives:
    Location: Myrtle Beach SC
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    I want to make sure that no one thinks I am speaking from absolute knowledge or experience but I would like some additional information about this subject.

    I agree that computers and tables would never have an issue in this depth range, but are you wearing your computer on these bounce breath hold dives? I bet if you do it beeps it's little heart out because it knows what gas is in your tissues beyond the surface saturation levels and the ascent rates you must use coming up will certainly violate the algorithm, I know that I try to make the last 15 feet take 45 to 60 seconds and even then my computer will occasionally chirp.

    My logic on this all is that once you have been on scuba you have gas levels in your tissues that is greater than pre-dive levels. As you decend these bubbles get smaller and move around searching for a way to off gas. Depending on where they move to you could have an issue, it seems to me. Dr. Jolie Bookspan writes in her Diving Physiology In Plain English that you can get DCS fro breath hold diving on deep repetitive breath hold dives. I understand that is not the case in this discussion the mechanism seems to be there.
     
  7. Dirty-Dog

    Dirty-Dog Frequently Censored ScubaBoard Supporter

    # of Dives: 500 - 999
    Location: Pueblo West, CO, USA
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    What "bounce breath hold dives"??? He made it clear that he's snorkeling at the surface but on SCUBA at the bottom. He's basically just doing a series of very short very shallow dives.
     
    shoredivr likes this.
  8. Diversauras

    Diversauras NAUI Instructor

    # of Dives:
    Location: Myrtle Beach SC
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    my bad, signing off now... going to my reading lesson
     
    Dirty-Dog likes this.
  9. bleeb

    bleeb Photographer

    # of Dives: 100 - 199
    Location: Ottawa, Canada
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    If you've already been scuba diving and have nitrogen in your system, repeated descents and ascents can cause "bubble pumping" which is one of the theories as to why people feel tired after doing a lot of them. Even the most benign dive on compressed air puts some bubbles in your blood stream, but most are filtered out by the lungs as they pass from the venous to the arterial side of your circulatory system, since it's on the arterial side as the vessels get smaller that bubbles can run into a hole too small to fit through and cause a localized stoppage. Descending can compress some bubbles enough that they can pass through the lung filter and when you re-ascend they grow back to their previous size, with the potential to cause tiny micro-strokes or other forms of oxygen starvation.

    As to how harmful this really is, I don't think there's much hard evidence either way. Lots of anecdotes about tiredness though, sometimes labelled "sub-clinical DCS". And the risk of precipitating a more serious problem is also hard to quantify.

    For more information, try the Ask Dr Deco forum. The topic probably comes up and gets reviewed at least once or twice a year.
     
    Hatul likes this.
  10. TMHeimer

    TMHeimer Divemaster

    # of Dives: 500 - 999
    Location: Dartmouth,NS,Canada(Eastern Passage-Atlantic)
    13,498
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    Good point dumpster. My 2 reasons are that as a shell collector you can cover much more ground (even in 5 feet depth) with scuba rather than going up & down. Also, with a 7 mil wetsuit scuba makes sense.
     

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