Sync with Diving Log

Discussion of the iOS App Dive Log
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Posts: 1
Joined: Mon Nov 20, 2017 3:19 pm

Sync with Diving Log

Post by JBow » Mon Nov 20, 2017 3:31 pm

When I sync from Diving Log 6.0, dives downloaded from my Cobalt 2 do not show an accurate air consumption rate. The rate is also not shown in the same location as dives from a different dive computer. Dives from my Oceanic VTX show the air consumption rate to the left of the tanks showing air pressure in Dive Log. From the cobalt 2 the rate appears above the tanks. The consumption rates appearing on Dive Log are also changed from those on the original entry on Diving Log 6.0. This is a new situation. In older downloads and syncs, the changes did not occur.

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Joined: Wed Mar 31, 2010 4:35 pm

Re: Sync with Diving Log

Post by support » Mon Nov 20, 2017 6:34 pm


I suspect that you are seeing a couple of different things here. First, in both Dive Log on iOS and Diving Log 6.0 the air consumption rate is calculated based in the depth profile (including average depth), the dive time and the tank size, tank start pressure and tank end pressure. There are many things that can affect the calculation, but I'm guessing that the most likely cause of the difference in the calculations done by Diving Log 6.0 and Dive Log is the option to ignore "shallow samples". By default, Diving Log 6.0 ignores samples that are less than 0.5 meters. Dive Log on iOS does not ignore these samples by default. However you can set the "Ignore Shallow Samples" switch to "on" in the Dive Log on iOS Settings tab (typically under the "..." or More tab by default on iPhone or by tapping the settings icon in the lower corner of the sidebar on iPad). I suspect that this will bring your air consumption rates into closer alignment.

The second thing that you are seeing is actually two different air consumption rates that Dive Log on iOS calculates. If you have a single tank specified for a dive then the air consumption rate for that tank is calculated and displayed next to the tank. However, if you have multiple tanks specified for a dive then Dive Log will try to calculate the per tank consumption rate and display that in the same place but it will also calculate the "average consumption rate" for the whole dive (that is the number that you see above the tanks). The catch is that in order to accurately calculate the "per tank" consumption rate we need to know when you switched between the tanks during the dive. This is information that may or may not be provided by your dive computer. If we do not have the tank switch information in your dive profile then we can not say for certain which part of the dive was completed with each tank. In that case, we only display the "average consumption rate" for the whole dive (i.e. we use the total dive time, average depth over the whole dive and the total air consumed by the two or more tanks tanks).

We try to be "smart" about when we can calculate the per tank consumption rate in a multiple tank dive if we don't have the "tank switch" information. For example, lets say you brought a safety bail out tank on the dive but you never used it. You can still specify two tanks for the dive, but since the second tank's consumption was zero we know that the first tank was responsible for 100% of the consumption rate so we show the consumption rate for that tank and the average for the whole dive (and they will be the same obviously). However, of some air was used from the safety tank, then we can't know for sure when you switched to it, so we don't attempt to display the air consumption rate for the first tank (just the overall average). There are more situations that that we look at when calculating the consumption rate in the case of CCR dives but that is a different discussion.

The difference between the VTX and the Cobalt 2 is likely due to one including multiple tanks and the other only including one tank (maybe you are using the VTX with multiple transmitters?). However, you would need to record the tank change during the dive to mark when that occurred (some dive computers allow you to "switch tanks/gases" during the dive). Now there is one final complication in all of this. Some dive computers (and some download software ... since you originally download the dive computers using Diving Log 6.0 I can't say for sure how each model is handled) can't make a distinction between a tank switch between two tanks that have the same gas in them (this is because they don't actually track tanks or transmitters but instead track gases) so no "tank switch" information is entered into the profile data and we don't have the information needed to accurately calculate the "per tank" consumption rate.

I hope that provides some background information to help you understand what you are seeing. If you still have questions about you particular situation, please feel free to contact us on our support email address (support 'at' moremobilesoftware 'dot' com) and I'd be happy to look at the details of your logbook. I will ask you to send me a copy of your Diving Log 6.0 logbook (the .mdb file) and I can start with that and upload it to Dive Log and let you know exactly why you see each value that you do.



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