Subsurface assigning start and end pressure to wrong tank/gas

[mcpowell]

When using my Teric, typically I have 4 active gases ready to be chosen, but this is just for gas selection convenience:
37%
33%
32%
21%
These are my most commonly used gases, but I'm only diving a single tank (not changing during dives). This allows me to quickly select my gas before the dive, without having to make changes to the active gases. However, I think this is throwing Subsurface a curveball, as Subsurface chooses the 37% gas to apply the start pressure and End pressure. On the dive below, I had my Teric set to 21%, but you can see how Subsurface is assigning the gas pressure to the gas in the top row of the chart.

I suppose I could turn off all but the active gas, and allow Subsurface only one gas to choose from...

Anyone else have this issue? Am I doing something wrong? Thoughts?

 

[harvalen]

Subsurface just gets a list of gasses and a list of pressures sensor from the dive computer, so it just pairs the first gas with the first sensor, and so on. It is probably possible to add some better heuristics by analyzing the full dive, but you'll still end up with corner cases like side mount divers using two sensor for their main gas and then a deco gas with no sensor. So far no one has bothered to try to come up with better heuristics, since it works pretty well for most people that have one gas and one sensor. For more complicated cases there is the option to fix the dive after you've downloaded it:

https://subsurface-divelog.org/subs...ixing_sensor_being_attached_to_wrong_cylinder

 

[greeniguana]

Only Enable (Turn On) Gases That You Will Actually Use on a Dive

My dive computer said the 20ft stop was supposed to take 4 minutes, but it actually took 10 minutes to clear. What went wrong? The answer is almost always that a more oxygen rich gas was enabled (turned on), but never actually used on the dive.

shearwater.com

 

[inquis]

Subsurface is assigning the gas pressure to the gas in the top row of the chart.

Right click the header row in the gas table and turn on the Sensor field. If it's wrong, use the Sensor drop-down on the correct gas to reassign the pressure info.

 

[mcpowell]

This community continues to impress me with y'all's ability to help!

​

harvalen: Thank you for that explanation.

greeniguana.: In the future, I will turn off all but my active gases for that dive. I didn't realize this was the correct thing to do until I read the article sited by you. Now it makes sense. Thank you.

inquis: I was able to turn on the Sensor field, but I can't figure how that helps when I only had one sensor. I'm likely missing something.

 

[inquis]

I was able to turn on the Sensor field, but I can't figure how that helps when I only had one sensor

If you were actually on 21%, click the (blank) sensor cell in that row and select the sensor ID (probably 0).

 

[inquis]

In the future, I will turn off all but my active gases for that dive. I didn't realize this was the correct thing to do

If you're staying within NDL, leaving the other common gases enabled yields a quicker way to select your gas rather than edit the digits. Yes, it's contrary to the documentation, but the docs are addressing quantities that are relevant when in mandatory deco. There are other threads on this topic if you'd like more details. Your call, of course; doing it "by the book" obviously works, just a bit slower.