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Thread: extended diving in shallow water

  1. #1
    TadPole
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    extended diving in shallow water

    Hi, first time post. I'm wondering about decompression sickness risk when staying in shallow water. If I were to stay at 15' or less, could I stay down all day, could I use 8 tanks of air, or is there still a risk at this depth? I am interested in doing some photography in some shallow water and would like to spend more time down if possible. Thanks in advance for any input and sorry if this isn't the best forum, I posted here because photography if my end goal.

  2. #2
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    At 15' or less you shouldn't have any decompression issues.
    Thanks,
    Joey

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    Megalodon
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    As a rule, you can theoretically stay down forever at less than 20' and not have a huge DCS/DCI risk However, you will still have Nitrogen tissue loading that you will need to track. The most recent Navy Diving Manual (http://www.supsalv.org/pdf/Dive%20Ma...%20Chg%20A.pdf ) Has 20' and less with no limit, 25' has a NDL of 495 minute and a 30' NDL of 391 minutes. For the NAVY DIVE TABLES, your max repetitive group is F for 10', I for 15', L for 20'.

    You still need to consider your tissue loading for things such as going from dive level to higher altitude, flying and changing your mind and performing deeper dives, etc

    And, in my opinion, this is the best forum to post these questions, we're a very friendly group that loves to help fellow divers! We also have few folks here that are phenomenal UW photographers that have been known to chime in on occasion.

    I once saved a man in Wichita just to watch him dive...(inventor)

  4. #4
    Grouper
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    One other thing to consider when diving that shallow - well maybe two.

    First - from there to the surface is the greatest pressure change for every foot. That means you have to be especally careful not to hold your breath. Lung expansion is a real concern (though you can't get to the surface without going through this zone - lol).

    Second - because of the same factor, being very properly weighted so you have very little/no air in your BC and having very good buoyancy control is important to prevent runaway ascents. With too much air in the BC even a foot higher will cause expansion of the BC and an increase in buoyancy.

    All that said, I dive mostly between 15-30 feet unless there is some reason to go deeper. Since I'm not into wrecks there seldom is for me. I've been down to the rec limit (130') and saw the garden eels - OK been there, done that - but didn't find much else there that wasn't in the 30' and shallower range. I prefer longer bottom times so tend to stay shallower than a lot of divers.

  5. #5
    Shark Zeagle Eagle's Avatar
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    Quote Originally Posted by Charon View Post
    One other thing to consider when diving that shallow - well maybe two.

    First - from there to the surface is the greatest pressure change for every foot. That means you have to be especally careful not to hold your breath. Lung expansion is a real concern (though you can't get to the surface without going through this zone - lol).

    Second - because of the same factor, being very properly weighted so you have very little/no air in your BC and having very good buoyancy control is important to prevent runaway ascents. With too much air in the BC even a foot higher will cause expansion of the BC and an increase in buoyancy.

    All that said, I dive mostly between 15-30 feet unless there is some reason to go deeper. Since I'm not into wrecks there seldom is for me. I've been down to the rec limit (130') and saw the garden eels - OK been there, done that - but didn't find much else there that wasn't in the 30' and shallower range. I prefer longer bottom times so tend to stay shallower than a lot of divers.
    I would much rather spend my time in the 15-30 range unless there is something interesting deeper. I still like Palancar Gardens/Caves/ and wall dives are fun. Nothing like launching off the top of cliff and going straight to 90. I know nothing to see; but, it's fun.
    --Zeagle Eagle

  6. #6
    Grouper
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    Quote Originally Posted by Zeagle Eagle View Post
    I would much rather spend my time in the 15-30 range unless there is something interesting deeper. I still like Palancar Gardens/Caves/ and wall dives are fun. Nothing like launching off the top of cliff and going straight to 90. I know nothing to see; but, it's fun.
    Agree. I love dropping over the edge at Cliff (Bonaire) though it's only to about 60'.

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    Shark Zeagle Eagle's Avatar
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    Quote Originally Posted by Charon View Post
    Agree. I love dropping over the edge at Cliff (Bonaire) though it's only to about 60'.
    There's a wall in Grand Cayman, can't remember the name. The top is at 15' and I do a superman off the top, arms out like a cliff diver, straight down to 90' screaming Banzai half the way down. It's a hoot and always takes my breath away. I love the feeling of the increase in speed as I go deeper and my body compresses. I would hit my inflator hose with a good shot of air at 90' to see if I could stop and be neutral with one shot. It's amazing how much air it takes.
    --Zeagle Eagle

  8. #8
    Megalodon
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    I did that at Beaver Lake the last time I was there. Medicdiver made me stop at 109' (to be fair, I was on 32% and my MOD was 111') I love doing the Banzai descent as well. I used to do that at Oronogo: Go down to the 20' hanging platform, blow negative and drop! There's a marker of sorts at 75' and that's where I hit the inflator and am just enough positive to stop about 3' off the bottom and then on tap to the deflator button and I'm neutral.

    I once saved a man in Wichita just to watch him dive...(inventor)

  9. #9
    Barracuda
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    The Banzai descent? Isn't that what we did in the 70's before BCD's calling it "rocket to the bottom".

  10. #10
    Megalodon
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    You know it!!!! Last one to 100' is Shark Bait!!!!

    I once saved a man in Wichita just to watch him dive...(inventor)

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