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Hi guys,

Great to be able to have multiple sets of tanks, but there are a couple of glitches that I hope will be fixed for the next release:

1) If setting the "main tank" as "double" it seems to be impossible to have the second tank as a single - un-clicking "double" for the second tank (tank 1) works, but does not get saved. Or maybe it is just the tick in the "double" check box that is displaying incorrectly, as the Environment panel does correctly display a single tank. Confusing!!

2) the calculated SAC rate does not seem to take into account gas usage in the additional tank/s.

Look forward to a fix

And a suggestion- if loading a dive profile that contains temperatures, is it possible to populate the air and water temperatures with values from the surface and deepest parts of the dive?

Best regards
Graham

Hi Graham,

(Assuming your talking about Dive Log Manager/DT here, not Dive Log).

1) If setting the "main tank" as "double" it seems to be impossible to have the second tank as a single ...

You're right - very confusing! Thanks for pointing out this bug. Will get this fixed ASAP for the next release.

2) the calculated SAC rate does not seem to take into account gas usage in the additional tank/s.

Well, we *think* we do. Perhaps this bug is getting in the way somehow, but you should see a per tank SAC rate. The exception is that if we don't have profile information for the pressure values and depth on the 2nd tank, we can't do a calculation. So let's say you have the main tank and Tank 1. When calculating the SAC for the main tank, we exclude all the samples found in the profile from Tank 1 and do the same (exclude main tank) when calculating for Tank 1. If there is no main tank profile data, then you can enter an "average depth" for SAC calculation purposes, but we don't have a way for users to enter "average depth" for additional tanks like Tank 1.

Few dive computers support the concept of "tank switch" and so depending on how the information got into the application means that maybe we don't have enough information. If we can take a look at one of your example dives, that might help. You could create a new logbook and just import the indicating dive and send it off to us and we could take a look.

And a suggestion- if loading a dive profile that contains temperatures, is it possible to populate the air and water temperatures with values from the surface and deepest parts of the dive?

Certainly possible. Although this is a bit of a philosophical question. So far, we have only populated these fields with information from the dive computer itself, or let the user enter it. Since we believe the dive computer is "the truth", we do not like to modify any information it has without the user's knowledge. So we left it empty on purpose if we didn't know how to read it from the dive computer or if the dive computer didn't have it. We could fill it in with our own calculated data if that was the case, but for all the different diving in the world, it's hard to know what to do. For example the surface water temperature is not necessarily indicative of the air temperature and people have different beliefs on what single number to use for water temperature based on thermal clines and personal experience on the dive. We just figure that if the dive computer doesn't have an opinion, then we should punt and let the user decide what it should be

Right now though, for Suunto computers, we don't "read" what the dive computer thinks the water temperature is. So if the dive computer has a temperature profile, we'll calculate the average and put that value in there. We had a lot of feedback from Suunto users that they wanted this so we did it. So things can change too with user feedback like this

Cheers,
Janice

Hi Janice, and thanks.

Yep- I was talking about Manager/DT. Hope that's ok.

I will make a sub-set of my log book and send it to you to see if you can see what is going on.

FYI I use a Shearwater Predator. In these dives both back gas and stage were Air, so I didn't need to do a gas switch. I put the volumes and start/finish pressures for all tanks into the programme. I would have thought in the average depth of the whole dive could be used with the volume weighted pressure drops to work out the overall SAC rate just fine. Actually the same applies whatever the gas, doesn't it? I can see that it would be great to calculate SAC for different gasses separately, but I'd be happy to have an average in the event of no gas switch information.

Cheers
Graham

OK, as we've learned, we have the notion of a tank switch which may or may not imply a gas switch. But the Shearwaters only have a gas switch which means you can't recognize a tank switch unless you change gasses.

But what you're really looking for is a SAC rate over the whole dive, not just on a per tank basis. I think we can do that. We'll look into it.

Janice

Hi Janice

I was adding the start and end pressure data on my Sidemount dives yesterday. I was not adding Gas switches, so at the end was getting an incredible low SAC for the first tank and no SAC for the second tank.
Did you implement the "all gas / complete dive" SAC alrerady?

As I can see, Divinglog is calculating this an writes it on the first tank. Maybe in a future version you both can add a field in the database. Then it would not interfere with the SAC / Tank.

Regards
Andi

Did you implement the "all gas / complete dive" SAC alrerady?

Yes, we did. The "per tank" SAC rate shows up on the Environment panel on the upper right hand side next to all the other tank data. It will only show if DLM/DiveLogDT has all the needed information to calculate it, which is start pressure, end pressure, tank size, (and working pressure if using Imperial units). But it also needs the average depth for the time you were using that tank which we would only have if your dive computer registered a tank change. So for a regular side mount dive, you probably wouldn't have this. Otherwise, we have no way of knowing what portion(s) of the dive you used that tank. One request we've had is to just use the average depth for the whole dive instead which we will probably do in a future release. It won't be that accurate, but it would allow divers to at least see trends or changes between dives.

For the "per dive" SAC, it shows up in the bottom right of the Environment panel where the "per dive" information is, next to "Gas" and "CNS". It add's up all the gas you used in all the entered tanks (as long as you've entered all the same information as mentioned above), and then uses the dives overall average depth to calculate the overall dive SAC rate. So your added sidemount tank would be accounted for here and you would see your overall dive SAC rate. This SAC rate will be the more interesting number for sidemount divers to look at.

So if you're not seeing the "per dive" SAC rate change when you add your sidemount tank information, please let us know.

Janice

Hi Janice
Thanks for your answer.
There was a lot of confusion on my side. I have not seen that this thread was about DLM.

Do you have the "whole dive" feature for the Dive Log (ios app) as well?

Kind regards
Andi

Hi Andi,

Sorry about the confusion. This tread started out on the "wrong" forum and we didn't move it (which in retrospect we should have).

The "whole" dive SAC rate is not in the currently shipping version of Dive Log, but it will be in the next release (which is currently in Beta). We are hoping to submit this new version to Apple for review very soon (within a couple of days) so I'd expect it to be available within a week or so after that (of course we have no control over the App Store review process so we can't guarantee any specific release date).

If this is an immediate need for you and you'd like to get access to the beta release, please let me know (via our support email address: support 'at' moremobilesoftware 'dot' com).

Cheers,

Greg

Hi Greg

Great! Thank you!

It is not very urgent, for most of my dives I havn't recorded the presure data. I'll be fine with the next release.

Regards Andi

I'm seeing SAC rate issues with multiple tanks too. Here's one example: A sidemount dive with 2 bottom gas tanks and two bottles with 50% and 100% for deco. The computer is a Teric. Dive Log Manager picked up three tanks from the gas switches on the Teric.

Main Tank shows 3,394-2,340 = 1054 psi used. It's a 3,442 psi HP Steel 100. I get 1054*100/3442 or 30.62 ft^3 gas used.

Tank 1 is the same size. There was 2,444-2,108 = 1336 psi used, for 38.81 ft^3 gas used.

Tank 2 is a 3000 psi 40 ft^3 tank, which dropped from 3200 to 2100 psi for 1100 psi used. That's 14.67 ft^3.

Tank 3 is the same size, with 3200 starting pressure, 2400 ending pressure, and 800 psi used. That's 10.67 ft^3.

Total gas used is 94.77 ft^3. The dive was in fresh water and the average depth is 62 feet for 50 minutes. The SAC rate, then, should be

( 94.77 * 34/(62+34) ) / 50 = 0.67 ft^3/min

Dive Log Manager 2.8.3 (2.215) shows 1 ft^3/min. The iOS Dive Log shows 0.55 ft^3/min. These are the overall SAC rates, not the ones for the individual tanks.

I guess I get close if I average the two programs, though.