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Can varying your SAC rate reduce/increase the likelihood of DCS?

Discussion in 'Ask Dr. Decompression' started by SammyW, Feb 15, 2019.

  1. boulderjohn

    boulderjohn Technical Instructor ScubaBoard Supporter

    # of Dives: 1,000 - 2,499
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    Neal Pollock recommended mild exercise during decompression in this presentation. It is near the end.
     
    Schwob likes this.
  2. jvogt

    jvogt Solo Diver

    # of Dives: 200 - 499
    Location: Lakewood, CO USA
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    I thought it was the other way around. You can have higher PPO2 because your not working as much. I'm not talking about running marathons, just a easy swim around. Beside, most of the time your not going to be at 1.6 anyway.
     
  3. KWS

    KWS ScubaBoard Supporter ScubaBoard Supporter

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    I agree you can have the higher PPO2's for the reason you said. You cant have it both ways higher PPO2's and higher activity to increase the matabolism. The accepted practice calls for them to be mutually exclusive. The lower activity level should keep the off gassing down also to a controlled rate. Other wise I would guess that even if you have a delta pressure of 1.5 the activity would risk raising the effect to 2.0 or more. You could probably do that after a calm first minute or so when most of the high rate off gassing would be completed. Im no expert so I may be talking out my back side but this is what I get out of the pages of talk, reading, and then self reasoning. So in my view you maximize the PPO2 in exchange for the protection of minimum activity. If you want to be active you lower your max PPO2 which raises you N2 % and slows the off gassing. Kind of counter productive depending how you look at it.
     
  4. CodeS

    CodeS Angel Fish

    # of Dives: 100 - 199
    Location: Sydney, Australia
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    Teach yourself how to solo dive and just complete the dive yourself, your buddy should be able to get back on the boat or to shore themselves.

    I always find the bigger issue is when dive operations limit dive time. Now that is endlessly frustrating (especially if there is no good reason). This is why I much prefer shore diving.

    Now I don't find my air consumption goes down on the deco line. I think it is due to not having perfected my buoyancy control yet so to maintain depth I'm just breathing more than I should. Albeit not often over 10L/min so I can't really complain.
     
  5. Diver0001

    Diver0001 Instructor, Scuba

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    Actually, the way I understand it, working hard(er) on the bottom is more of a concern that being relaxed at deco. You don't need to be concerned so much about a marginal difference in off gassing as much as the increase in "on gassing" during the working phase of the dive.

    If it's concerning you, you'll probably be better off leaving the bottom a couple of minutes earlier than extending deco.

    R..
     

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