CNS computing mistake

[JB2Cool]

Daniel,
What exactly is your plan? It could be that they are just planned
differently. Are you planning to descend and then do 30 minutes on the
bottom leaving the bottom at around 33-35mins runtime or were you planning
of leaving the bottom on 30 minutes meaning that some (3-5 minutes) of that
30 minutes is your descent and a smaller portion (25-27 minutes) is the
actual bottom time?

Once I know exactly what you are trying to plan we can ensure that the same
calculation is taking place everywhere.

Jason

On Tue, 7 Mar 2023 at 16:36, JB2Cool <jb2cool at gmail.com> wrote:

> It's not a comparison with Shearwater or your manual method but Baltic on
> the phone gives me 70% CNS and 104 OTU on a 74 minute runtime so very close
> to the Subsurface figures. iDeco Pro is giving me 64% and 84 OTUs on a 65
> minute runtime (iDeco Pro i can't see the descent, it seems to start at 50m
> so probably what accounts for the shorter runtime and some of the missing
> OTUs.
>
> Can you share your Shearwater planning at all or is it all on the screen
> of the device?
>
> JB
>
> On Tue, 7 Mar 2023 at 16:23, Daniel Miazek via subsurface <
> subsurface at subsurface-divelog.org> wrote:
>
>> Hello Everyone.
>> I think that there is a mistake in computing/calculating CNS.
>>
>> I've noticed this when I tried to plan a diving on 50 meters and
>> 30minutes bottom time (including falling down), with 24litres air, 11litres
>> nitrox 52%, and 6litres oxygen (nitrox 99%).
>> I used Bulhmann algorithm with 20/80 GF, SAC 19l/17l, PO2 1,4bottom, 1,6
>> deco. All ascending speeds 10m/min.
>>
>> Generally speaking Subsurface turned out 72 minutes diving plan
>> indicating that CNS will be 66%, OTU 103.
>>
>> I've compared this with my sharewater petrel 3 planner and manual
>> calculations, and both turned out CNS values close to 49%.
>> Diving time, gas usage and OTU was almost the same.
>>
>> I can share print screens and a file with this particular plan.
>> Maybe I made saome mistakes in other configuration settings, but I'v
>> checked everything several times and everything seems to be ok, except CNS
>> calculations.
>>
>> Would be gratefull for any comments or clues.
>>
>> Daniel
>>
>>
>> _______________________________________________
>> subsurface mailing list
>> subsurface at subsurface-divelog.org
>> http://lists.subsurface-divelog.org/cgi-bin/mailman/listinfo/subsurface
>>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.subsurface-divelog.org/pipermail/subsurface/attachments/20230307/3a4e87b7/attachment.htm>