Clarification on air consumption profile calculations

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sdridentity
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Joined: Sun Nov 05, 2017 12:24

Clarification on air consumption profile calculations

Post by sdridentity » Tue Nov 07, 2017 23:41

Hi,

Well done, congrats on 20th anniversary :-)

I experience some behaviors I do not understand with the air consumption profiles -- Using 6.0.11 (Update 1).

If I take three dives from my logbook:
Dive 1: Start and End Pressure set, Avg Depth set, DC Profile, NO DC air measures (Vyper) Profile 2 data shows values
Dive 2: Start and End Pressure set, Avg Depth set, DC Profile, NO DC air measures (Vyper) Profile 2 data shows NO value
Dive 3: Start and End Pressure set, Avg Depth set, DC Profile, DC air measures (Vyper Air) Profile 2 data shows values

If I set Profile -> Profile 2 to Tank Pressure 1, profile 2 Graph shows:
Dive 1: a linear trend from start to end pressure
Dive 2: no profile (empty)
Dive 3: the recorded profile values

If I set Profile -> Profile 2 to Tank Pressure (calculated), profile 2 Graph shows the correct calculated SAC for all three dives.

My questions:
Q1: Why is the Profile 2 data of dive 2 empty? Normally, it gets populated when Start, End and Avg Depth are set? I assume this is also why the graph is empty... I have 4 dives like that. In Tank & Gas detail, everything looks ok, even with a SAC calculated value
Q2: Is there a way to set things up so the recorded (DC) air profile data is used, and if absent, revert to SAC?

Thanks!
Simon.

divinglog
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Re: Clarification on air consumption profile calculations

Post by divinglog » Wed Nov 08, 2017 01:33

Hi Simon

Thank you very much!

Tank Pressure 1, 2 & 3 is always recorded data from the tank pressure sensor, never calculated or populated from manual data. Only Tank Pressure (Calculated) is calculated based on start pressure, end pressure, depth and SAC rate. So Dive 1 must have tank pressure values from somewhere. Maybe you've drawn them in the profile editor some time in the past?

Kind regards,
Sven

sdridentity
Posts: 5
Joined: Sun Nov 05, 2017 12:24

Re: Clarification on air consumption profile calculations

Post by sdridentity » Wed Nov 08, 2017 03:36

Thanks.

Most of the data (like Dive 1) was imported from Suunto DM 3.1. This is probably where the interpolated tank pressure data comes from (as I did not enter detailed tank pressure data myself).

Assuming that, is there a way to have, in one logbook, the pressure graph showing the "best available" tank pressure data, i.e. the sensor data when available or the calculated otherwise? Or alternatively, is there a way to "generate" the tank pressure data points from the start/end pressure depth and SAC?

Thanks,
Simon.

divinglog
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Re: Clarification on air consumption profile calculations

Post by divinglog » Wed Nov 08, 2017 20:32

Hi Simon

Yes, maybe Suunto DM has interpolated the data. I don't think an "automatically pick the right profile" cannot be implemented in a non confusing way. Normally users have either an air integrated dive computer or not. Users without AI computer will always pick the calculated profile and users with AI sensor will pick the measured profile. I can't imagine how to implement such an automatic function so user will know what it does.

Sven

sdridentity
Posts: 5
Joined: Sun Nov 05, 2017 12:24

Re: Clarification on air consumption profile calculations

Post by sdridentity » Wed Nov 08, 2017 21:13

Hi,

I understand this may not be a very typical scenario. Although I imagine many who have
dived for some time probably went through more than one computer model and setup.

I did find a workaround, at least to print the log correctly.

I created two report files: one with Pressure 1 Content and one with PressureCalc Content.
Then I can print ranges of dives using the relevant report.

To clarify the function I thought was simplest to use: in the profile editor, there could be a
function to "Write the calculated pressure to Tank x Pressure" field, as a one-time action.

Thanks, and hope this helps.

Simon.

divinglog
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Re: Clarification on air consumption profile calculations

Post by divinglog » Wed Nov 08, 2017 22:12

Hi Simon

Yes, in profile editor such a function could make sense. I think it might be indeed useful to automatically create a tank pressure profile.

Kind regards,
Sven

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