Hi Michael,
Couple of things that can cause the difference.
First, the Atomic Cobalt is the only computer that we support that gives you the average depth of the dive when you download a dive. When we draw the "average depth line" on the profile display, we just do the basic calculation over all the samples we have. The sample interval the Cobalt uses is pretty "coarse" at 30 second intervals, so if you think about your depth profile over time, a 30 second interval doesn't give you a very accurate average depth. But the Cobalt itself knows your depth while you're diving of course and so the average depth it delivers with the profile information on download is much more accurate than our own calculation from the samples. So we use *that* average depth when calculating the SAC, *not* the average depth shown on the DLM profile display. Right now, there is no good way for you to see the former since the Cobalt is the only one that does this. If you are motivated, I can tell you where the file is that it is stored when you download.
Second, when we're calculating the SAC rate, we don't use the Dive Time as entered in the Dive Details. We use the time as calculated from the profile as the actual dive time. Since the Dive Details time is shown only in minutes, it does not take fractional minutes into account. So if you look at the profile for your example dive, see how long the profile is. With the Cobalt, we see generally two or three more samples after the listed dive time. So if your dive is shown as 38 minutes, you probably have 39 minutes of profile. And you'll probably see that your depth does not become "zero" until the last sample. So "generally" (but not necessary always), the profile is a more accurate representation of your dive time.
The Cobalt probably uses the more accurate average depth in it's calculations, but I thought it was important to mention if you are doing the math yourself that you'll see a difference. The likely cause for the difference is the dive time. It can be a minimum of 1 minute and as much as 1.5 minutes longer using the profile and waiting for a zero depth. The Cobalt may use the time based on when you reach less than 5 meters or 15 feet - I'm not sure what they use. But since it is reporting your Dive Time as 38 minutes, I'm betting that they use that number.
What about a german translation of your software? I'd like to have both (Mac/iOS) in my native language.
Ooooooooo, I'm so sorry about that. We have been saying "soon" for a while now and we still haven't done it :( For German or any other language. Once one is done, the rest become easier. Unfortunately there are always so many features that we want to add and "internationalization" just keeps getting pushed down the priority list. We have many German users who have made the same offer, we just haven't done it. The good thing is that MacOS 10.9 added some great new features to make it less work for us! So we were kind of waiting for that for awhile. Maybe now if we wait long enough, Apple will figure out how to just make it happen magically with no work on our part? :lol: Just kidding. It's still on the list.
Thanks for your understanding,
Janice