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Off the chart on the dive tables

Discussion in 'Basic Scuba' started by Alligood, Aug 9, 2017.

  1. Alligood

    Alligood New

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    Those are total dive times. Bottom time was much shorter of course, we may have spent 15 minutes at 90. I do have a dive computer, but it was my first day with it. Darn Manual came on CD only.
     
  2. Alligood

    Alligood New

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    This was a refresher course
     
  3. Marie13

    Marie13 Great Lakes Mermaid ScubaBoard Supporter

    # of Dives: 200 - 499
    Location: Great Lakes
    9,191
    7,860
    Which one do you have?
     
  4. Alligood

    Alligood New

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  5. Basking Ridge Diver

    Basking Ridge Diver Solo Diver

    # of Dives: 200 - 499
    Location: New Jersey
    1,966
    1,010
    Yes poorly worded from my end. I would have stuck with the air tables through out - even though I was diving Nitrox. I was thinking he wanted to know how the Nitrox tables worked as well.

    And to the points above that is the great thing about dive computers...
     
  6. Aviyes

    Aviyes Contributor

    # of Dives: 100 - 199
    Location: Colorado
    441
    365
    I have never compared the 2 tables, may have to tonight. But, I would make the assumption at this time that the pressure group is the same on either table, as it relates to estimated residual nitrogen in your body. You would want it standard for adjusting between 21%, 32% and 36% tables on repititive dives of different profiles.
     
  7. victorzamora

    victorzamora Solo Diver

    3,041
    1,382
    There's two ways of doing it. One is the way described earlier which is the one you're referring to: Maintaining the Pressure Group through the Air, EAN32, and EAN36 tables.

    But what if you're diving EAN28 or EAN 34? Equivalent Air Depth (EAD) is how I'd go about it if not diving something other than a "standard" Nitrox blend that I had a table for.
     
  8. BoltSnap

    BoltSnap Dive Charter

    # of Dives: I'm a Fish!
    Location: Nomad
    6,846
    2,879
    Terrible attitude, terrible lack of knowledge, practice of dive planning and use of dive tables, terrible advice/attitude of instructor/divemaster, terrible everything.

    You need to take a dive course all over that covers decompression theory, dive tables and dive computers and get a good grasp on all of these issues and especially dive planning for deco and in general.

    Dive computers must not and should not be used to replace and in place of proper and adequate training and understanding of deco. theory and dive tables. If you are unable to understand why it is a problem to make such short SIT and these extremely aggressive and inappropriate dive profiles, you won't understand and appreciate what the dive computer is telling you and what it is doing in addition to interpreting what the information is displaying means.
     
    yle and Bob DBF like this.
  9. runsongas

    runsongas Contributor

    # of Dives: 500 - 999
    Location: California - Bay Area
    4,635
    2,231
    you could calculate the last dive using EAD

    but tables are not going to be accurate with multilevel dive profiles

    if you switched your mix correctly on your dive computer for the last dive and you were within NDL, then I would not be worried. the computer would be more accurate than trying to use tables for the calculation.
     
    KeithG likes this.
  10. KeithG

    KeithG Guest

    Additional information will allow you to get more pertinent feedback.

    I am going to make the assumption that you wore your computer and did not excede its NDLs. I am also going to assume that as part of the "nitrox course" your computer was set to reflect the Nitrox mix on your last dive. Please let us know if these assumptions are incorrect as they will guide feedback.

    If my assumptions are correct, your set of dives is a great example of how hard it is to map a set of multi level dives back to tables - and to your perception of what you actually did on each dive. Tables assume a square dive profile. This is reasonable since in the old days the only reliable data post dive is the depth telltale on your mechanical depth gauge and the elasped time on your bottom timer. Limited reliable data means the tables are set up based on worst case scenario of a square profile. Doing multi level dives (which it appears you did) means you are further away from NDL limits than the table says.

    Using a computer is whole different world. By computer your first dive is almost a non dive. Total dive time was 30 minutes, mostly above 30 feet but you did hit 50 feet. Lets assume 5 minutes at 50 feet. That is 5 minutes of 63 minutes allowed by the PADI table. By the table (30 minute square profile) you were almost half way to NDL, but by computer you would be less than 1/12. The rest of the dive was above 30 feet. Same dive, very different interpretation of your loading.

    Can you confirm you used the computer and never went into deco?
     
    Neilwood likes this.

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