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Deep6 Excursion - Repetitive Dives, Surface Intervals, Residual Nitrogen and Dive Planning

Discussion in 'Computers, Gauges, Watches & Analyzers' started by SpecialTest, Mar 22, 2021.

  1. lowwall

    lowwall Contributor

    # of Dives: 200 - 499
    Location: Chicago
    You don't have a fancy dive computer, you have a basic one. I don't know of any basic computers that have that functionality. Some more advanced computers have a planning mode that will show you NDL times at a user selectable Surface Interval (SI).

    BTW, it's neither helpful or even possible to accurately calculate the length of time it takes to fully offgas. From DAN's The Nitrogen Saturation Myth "Once a diver has returned to the surface, regardless of whether the dive was a short recreational dive or a long saturation dive, all tissue inert gas in excess of normal atmospheric pressure will be eliminated over the following 12 to 18 hours (in other words, his body’s tissue nitrogen levels will be re-equilibrated to the ambient atmospheric pressure)."

    This isn't normally a problem for recreational dives. You just wait out the SI until your computer shows you the NDL you want at the depth you want. If you have a tight schedule to keep, then you should be using dive planning software to plot out the day's dives in advance.
  2. greeniguana

    greeniguana ScubaBoard Supporter ScubaBoard Supporter

    Use V-planner. You could could figure out your repetitive dives on your couch before you get on the boat.
  3. SpecialTest

    SpecialTest Registered

    # of Dives: 0 - 24
    Location: Great Lakes
    It seems like useful information
    So Plan Mode's displayed NDL is affected by any residual gasses? If so, that basically solves what I want, but displays it in a different way... so it'll work fine.
  4. rhwestfall

    rhwestfall Woof! ScubaBoard Sponsor

    # of Dives: 200 - 499
    Location: "La Grande Ile"
    Yes. That is why I said upthread the method of comparing bottom time available (with residual nitrogen loading) vs. dive time desired is what most all do with repetitive dives.
    SpecialTest likes this.
  5. SpecialTest

    SpecialTest Registered

    # of Dives: 0 - 24
    Location: Great Lakes
    That's easy enough.
  6. sea_ledford

    sea_ledford Captain

    I think what the OP is getting at would be a plan function that has not only an option of "if I go to 60 feet right now, my max bottom time at 60 feet is XXX", but also a "If I wait another 30 minutes then go to 60 feet, my max bottom time at 60 feet is YYY"

    While that would be somewhat useful, you should use an app to plan to that detail, as the user interface to make that happen on a dive computer would be so complicated that no one would use it anyway. The plan modes are generally fairly useless anyway since most divers do not do square profiles. It really only provides a table profile based on your current saturation.
    SpecialTest and Tournesol2000 like this.
  7. scubadada

    scubadada Diver Staff Member ScubaBoard Supporter

    # of Dives: 1,000 - 2,499
    Location: Philadelphia and Boynton Beach
    My Teric does exactly that. You can run the plan now, or in 15 min increments in the future. The computer planner is absolutely simple to run.

    I disagree, the NDL planner is very useful to check your NDL for repetitive dives assuming you know the approximate max depth. It is particularly useful when the SIs are on the shorter side. I use my planner frequently. To each their own.
    SpecialTest likes this.
  8. tursiops

    tursiops Marine Scientist and Master Instructor ScubaBoard Supporter

    # of Dives: 2,500 - 4,999
    Location: U.S. East Coast
    I think what the OP was looking for was just the normal Plan function, but he didn't know what it did.
    inquisit likes this.
  9. sea_ledford

    sea_ledford Captain

    Shearwaters are the exception to the difficult user interface rule. Have you used one of the typical 4 button watch style computers? Stupid complicated. Why do I need to do short AND long AND combination presses? There are FOUR buttons! One button computers were easier to adjust! Sorry rant over...

    You are correct on the second point. My recent experience is teaching classes or diving deco, so I'm unused to planning 70-80 foot dives with an hourish SI then a 60 foot dive like on a dive boat. Used it all the time for that.
  10. SpecialTest

    SpecialTest Registered

    # of Dives: 0 - 24
    Location: Great Lakes
    I was actually looking for something closer to @sea_ledford said, and @scubadada described. But you are correct in that I didn't understand what the Plan function did. I had mistakenly thought it was basically static data that wasn't impacted by your current tissue states.

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