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Diving - Issue with NDL canculation when ascending

2876082
9 months ago

. At 40m I had 3 min NDL when starter ascensing. At 30m 2 min. From 30 to 18 no additional minutes. At the contrary it.indicated a compulsory stop at 4,5m...

My dive buddy (Suunto) had 14m NDL when I want to 0...

Any solution ?

  • 0 9 months ago

    Maybe different algorithms or different settings for decompression conservatism?

  • 0 9 months ago in reply to Adam-1972

    I would like to know the reason and correct. For info, I used the preset settings. 

    Anyone has the same issue .

    Basically after a deepdive I have no other option than speeding up the ascension...

  • 0 9 months ago in reply to 2876082

    Why you don’t check your buddy computer settings?

  • 0 9 months ago in reply to Adam-1972

    He doesn't have a garmin MK3 

    And nothing spécial about my settings...

  • 0 9 months ago

    I'm not sure what sort of "solution" you're looking for here. Garmin dive computers use the Bühlmann ZHL-16c algorithm. Some Suunto dive computers use the same algorithm, so if your buddy has one of those and you both adjust your gradient factors to match then you should get similar results. Other Suunto dive computers use different algorithms such as proprietary modified forms of RGBM. Those are always going to generate different NDLs and deco stop times.

    As to which algorithm is a more accurate model of real diver physiology, that is still a matter of some debate. If you're going to push close to the NDL then you ought to learn decompression theory and don't rely too much on what any particular dive computer tells you.

  • 0 9 months ago in reply to nradov

    well said, problem is not that tthe OP cannot match the suunto NDL, but the lack of knowledge why there is a difference. And why you should not expect same results, after all I doubt tge dive profiles are exact match either.

  • 0 9 months ago in reply to nradov

    Thank you. 

    I understand. I am actually wondering if my computer shows the expected values or needs fixing...

    It just that the diving profile with no deco is challenging. In addition compared to my previous computer and other divers ones, there a huge différence. 

  • 0 9 months ago in reply to 2876082

    Garmin devices correctly implement the documented algorithm and produce results consistent with other devices that implement the same algorithm with the same GF settings. Like if you run Garmin and Shearwater dive computers side-by-side then the outputs will be nearly identical. It is unlikely that your device needs fixing.

    If you want a longer NDL then you can increase the High GF %. Or switch to a different manufacturer's device with a more "liberal" algorithm.

    I'm not trying to be a jerk here but the fact that you're asking such questions indicates that you're unclear on the basics and are running risks you don't even understand. I recommend you take a step back and complete some more advanced training before you hurt yourself.

  • 0 9 months ago in reply to nradov

    You're kinda though. 

    Anyways, I am not trying to have longer NDL. It's just that it seems that the NDL is stuck at 2/3 minutes and.even decreasing eventhough I am ascending...

    I will test with 2 computer usine.the same algorithm (another garmin and a shearwater) and the result will solve the question. 

  • 0 9 months ago in reply to 2876082

    I would suggest instead checking it with other computers which algorithms and settings you don’t know. 
    Check it with official dive time tables. 
    You should have such from scuba dive course you did.