Tec dive - crazy CNS

Did a dive the other day with 2 stages (50 & 100) - My Decent was alerting me through deco that my CNS was waay high (+100%) - but my plan was not anywhere near that, 50m for 25 mins (21/25). With air (tmx) breaks on 100 every 5 mins for 2 mins.

My end CNS on Garmin came up with 163%, Multideco plan gives 34%.

My backup Shearwater didn't give me an indication of anything wrong.

Is there anywhere in the Garmin settings that this can be reviewed? - I've given it a solid look through, and I think the answer is no - Where would be the best place to report this potential "bug"?

thanks!

0 atj777 over 4 years ago

I have not noticed any issues with CNS with my Mk1 while diving. I just checked the CNS from previous dives and they are all in line with the values from my Perdix AI for the same dives. There may be a small delay (5-30 seconds) in when they move up to the next % but they were never more than 1% out.

Given that it appears you were switching between 50 and 100% O2 on your deco stop (if I'm reading that correctly), is it possible you forgot to tell the Mk1 about the gas switch? i.e. you went from 100% to 50% and told the Shearwater but the Mk1 still thought you were on 100%?

0 crazylolo over 3 years ago

hello i had the exact same things dive at 35m with sidemount and deco stage 1 at 36 the other on O2 the garmin keep anoying me during the deco at 6 i finish with 40% CNS on the sherwater and 130% on the MK1 even there is 2 change compare to the sherwater the MK1 was set on fresh water (1m difference at 34m) by accident and it has change gaz alone for 5 min at 32m with the 36% instead of the 30% ... an increase of 10% on the mk1 can be ok but 70% no way !

2 years after more than 30 tech dive and i confirm that the garmin is NOT good for tech dive CNS computation issue (no Pb of water density altitude ect all check before going UW) PO2 is wrong with hight O2 at shallow depth (but good at depth) alarm masking the depth is BIG NO