Strange deco stop depths

I wanted to checkout the deco view/behavior of my new garmin and went into minimal planed deco. While diving on 28 nitrox, the garmin was set to to air with GF 44/77. After less than 10 minutes on 20 meter and further 8 minutes on around 30 meter the garmin showed me a deco obligation and my first stop should be on around 18 meter for ~30 seconds and the second on ~13 meters for around 1:30 minutes. The next shallower stop was then cleared during further ascent, while I was still below 10 meter.

Given the fact that my GF low is quite "aggressive", I find it strange that my garmin descent mk2i gave me so deep deco stops. Additionally the fact that all shallow stops were 100% cleared although my GF High was set to conservative doesn't give me much confidence.

I tried to replay the dive using MultiDeco and could only get similar deep stops by using a GF low of 20 or lower.(i.e.: 20/75) (still would need 5 minutes of shallow stops). The closest I could replay here with MultiDeco was by setting 20/95, which is clearly not what I want (with still 3 minutes shallow stops).

Also strange: The ceiling shown in my dive connect app doesn't show my deco stop obligation, but instead shows a ceiling on 6 meter and 3 meters, which is something I would have expected.

Can someone explain this behavior? To me this feels a little bit buggy.

0 NotGoodInLycra over 1 year ago

Hi @2898158

i concur, and do not trust the planner, this issue was the same on the MK1 (assuming that these threads are accurate).

the NDL times are very conservative as well when compared to Baltic and my Perdix. The Garmin deco planner does suggest that it is not using the GFs that are set, or that it is not using Buhlman ZHL16C at all. If Garmin want to be taken seriously they should fix this or publish the differences.

I, and I think, the majority of divers who have elected to buy a computer using The Buhlman ZHL16C algorithm have an understanding of what the algorithm is, and because of this, we have the knowledge to find multiple reliable resources to check the results.

I think that Garmin should spend some time and money looking at their audience and competition instead of marketing, this may lead to either improving their customer service and providing a product that warrants the hefty price tag, or changing the pricing model and competing with manufacturers of products at a different price point.

I am not sure that they have spent enough time on the dive planner and this should be taken more seriously as it feeds into gas planning. Disappointed.