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NDL different from SSI tables ??????

Discussion in 'Genesis' started by scubabeachboy, Feb 26, 2016.

  1. scubabeachboy

    scubabeachboy Nassau Grouper

    # of Dives: 50 - 99
    Location: Virginia.
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    Anyone on Scuba Board,.....
    Please try to answer this question:
    I was comparing my dive computer (Genesis Reat-Pro) to traditional dive tables.
    In the dive plan mode the NDL (No Decompression Limits) on the computrer are significantly longer than a traditional dive table limits.
    The computer values come closer to table limits as the depth increases, however, even at 90 feet they are still longer bottom times....
    I think that the traditional dive tables (SSI) are more conservative ?????
    I tried this with air, EAN32 and EAN36.
    All had the same problem ????

    I have made no dives in several days.
    The SSI table is one year old.

    Anyone have an idea?????
     
  2. Oldbear

    Oldbear Teaching Neutral Diving

    # of Dives: 1,000 - 2,499
    Location: Marshall Islands and Westminster, Co
    2,668
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    113
    The dive tables are much more conservative the dive computer. Dive tables are static where as computers are constantly taking samples so they can make adjustments during the dive.

    Also the two could be based on two different dive algorithms.
     
  3. scubadada

    scubadada Diver Staff Member ScubaBoard Supporter

    # of Dives: 1,000 - 2,499
    Location: Philadelphia and Boynton Beach
    9,971
    5,285
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    The answer is different decompression algorithms.

    The Genesis computer runs the DSAT decompression algorithm. This has been the standard for Pelagic Pressure Systems computers (Oceanic, Aeris, Sherwood, Genesis...) for quite a while. More recently, they have also offered a more conservative algorithm (PZ+, a Buhlmann ZHL-16C variant) as part of their dual algorithm. The DSAT algorithm is one of the most liberal and is also the basis for the PADI RDP, only slightly more conservative than the Navy tables.

    I don't know the exact basis for the SSI dive tables but imagine the algorithm is more conservative than DSAT, explaining the differences in NDLs you have noticed. With some searching, one could probably discover the basis for the SSI algorithm.

    I have over 1000 dives using the DSAT algorithm and Oceanic computers since 2002
     

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