Desat time on Atom 3.1 on Nitrox vs. Atom 2.0 on Air into Deco

I had an interesting experience (twice) while diving in Grand Cayman recently.


I purchased an Atom 3.1 recently and was diving on Nitrox with it as my primary computer and using my old Atom 2.0 as a backup.


I had set FO2 = 32% on the Atom 3.1 and just left the Atom 2.0 in my pocket configured for Air. They were both on the same algorithm as well. The Atom 2.0 went into Deco (expected) but at the end of the dive the Desat time on the Atom 2.0 was shorter than the Atom 3.1.


The desat times were not far off, but the Atom 3.1 which never went into Deco was at 16:12 while the Atom 2.0 was at 16:05. The previous time this happened the difference was closer to about 15-20 minutes.


The max depth on both was 108' with a total dive time of 55 minutes on both.


This seems strange to me since they were both on the same exact profile and the same surface interval since the previous dive but the Atom 3.1 never went into Deco and had longer Desat time.


Why would that happen?

Thanks,

- brett

I would download both computers and send the information to oceanic.Also what software version is on the atom2.

I had this happen again this weekend but haven't had a chance to send the dive data in to Oceanic. However, I think I figured out why it would happen.

I'm assuming that the Atom 3.0 is making calculations based on actual air consumed at each depth since it is getting a pressure feed from the sensor. I disabled the Atom 2.0 from receiving the tank pressure readings so it must be calculating nitrogen absorption based on time/depth only.

Does that seem plausible?

If I get time this weekend I'll download / export the data and send to Oceanic. Do you know which export format is best to use?

That is not it. They both use depth and time for calculating nitrogen absorption. If you were using gas for nitrogen absorption you would also need cylinder size als well.
Send them the DLG file and you can upload your text file here.

NCadiver:

That is not it. They both use depth and time for calculating nitrogen absorption. If you were using gas for nitrogen absorption you would also need cylinder size als well.
Send them the DLG file and you can upload your text file here.

Click to expand...

I've attached the different txt files for both the Atom 2.0 and Atom 3.1. There are 4 different dives across 5/10/12-5/11/12. The resulting delta in DSAT time was that the Atom 2.0 was seven minutes less even though it went into deco. I dove FO2=32% on the Atom 3.1 for the first dive on both days.

There are 4 dives on 6/23/12. The variance was even larger on this set of dives. I dove FO2=32% on the first dive only. The difference in DSAT time for this series of dives was that the Atom 2.0 was at 23:15 when the Atom 3.1 was at 24:10 -- almost an hour difference.

Do you know who/how I should upload the DLG files to Oceanic?

Send them the DLG file as is and oceanic can proceed from that point. But I did notice that the dive time and elapsed time were different and one miss a dive as well. The 3 showed dive one and the 2 showed dive 2 for the same period.
The reason I did not have you post your DLG file here it may contain personal information.