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is there a way to calc average depth from 2 specific points in a dive?

Discussion in 'Shearwater Research' started by KentB, Mar 31, 2019.

  1. KentB

    KentB Barracuda

    # of Dives: 200 - 499
    Location: Vancouver

    I have 2 perdixs, 1 AI 1 non AI. is there a way to calculate average depth from 2 specific points in a dive graph? ie a very task loaded 10 or 15 min bottom time or just during gas switch for deco stops?
    reason Im asking is im doing my first tech course and i know my average RMV is 0.6- .65. on a normal dive and the Instructor yesterday really hammered me with task loading and my RMV was still above (not a lot but a bit ) over my calcs using 0.8 as an RMV but my deco volume i used was much much lower than I planned for.

    Id like to be able to select say dive min 10-20 and get an accurate depth and min 50-80 of simulating deco stops without taking as many points as I can see and work it out manually.

  2. Shearwater

    Shearwater Dive Equipment Manufacturer

    Hi, @KentB . Currently you can set up one of your Perdix in gauge mode and use the resettable average depth feature of the gauge mode. We may be having this feature available in other modes soon through an upcoming firmware release. We cannot promise a timeline on any future release.

    Keep in mind that while on the surface, the MAX and AVG values display the maximum and average depth of the last dive. The AVG depth displayed on the surface is for the entire dive, regardless of whether the reset average depth option was used. The dive log also records the average depth for the entire dive.
    racanichou likes this.
  3. boulderjohn

    boulderjohn Technical Instructor ScubaBoard Supporter

    # of Dives: 1,000 - 2,499
    Location: Boulder, CO
    The situation you describe is a common part of technical diving training, and I would be very interested in a good solution. I did not know about the ability to reset average depth. I think that is very valuable.

    The current standards for the courses I teach tell me to set aside specific times for students to swim for specified times at specified depths and keep track of gas usage during that time. Aside from being a PITA, that artificial construct is very inaccurate, especially for people not using AI computers. (Look at how much gas you used in your doubles over 10 minutes on an analog gauge and tell me how confident you are in your calculations.) I much prefer to have students do a normal dive and use gas usage and average depth over that longer time, but then you run into the problem of separating deco usage from bottom usage.

    So, I am not so much offering a solution as much as suggesting that tech instructors would really like to see a way of doing this effectively.
    racanichou likes this.
  4. KenGordon

    KenGordon Rebreather Pilot

    Can’t you get the data out as a cvs or xml file and look at it? I am pretty sure I have done this, maybe by exporting from the desktop app. Or maybe that was another brand.
    rhwestfall likes this.
  5. zeno nox

    zeno nox Garibaldi

    # of Dives: 500 - 999
    Location: Belgium
    If you're not a PC user: MacDive has a selection tool...

    Schermafdruk 2019-04-02 12.25.40.jpg
  6. rhwestfall

    rhwestfall Solo Diver

    # of Dives: 200 - 499
    Location: "La Grande Ile"
    export the data to a spreadsheet, and analyze whatever portion of the dive you want....
  7. seeker242

    seeker242 DIR Practitioner

    # of Dives: 200 - 499
    Location: Pompano Beach, FL
    And on PC, Subsurface can do this also. :)
  8. KentB

    KentB Barracuda

    # of Dives: 200 - 499
    Location: Vancouver
    Yes we have been doing that as well but i haven’t done it while I’m been getting hammered hard with drills and skills and testing.
    I’ve calculated the whole dives for the last 50-60 to get my average RMV
    But would be interested in separating bottom time and deco time rmvs

    I will look into the programs listed below and average depth reset.

    Thanks everyone!!

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