stop too long ?(ostc vs vision )

[papamorse]

Hello, I use my ostc in backup of my evolution vision. In general stops are comparable. But by twice the ostc added me more than 15 minutes of stop (on dives for approximately the 1 hour). Anybody already has you he had that?
setting vision ppo2 = 1.3 gf 30/75 ostc : ppO2 = 1.2 gf 30/85 diluent 10/50

[corona_citron]

yes. I had the same problem last week during a cool cave dive in the Lot.
About 60 at +/- 25 m. PPO2 1.2, V1.30, GF 30/85, TX10/50.
At the end of the dive, the ostc shows me 18 min. Ten seconds later, it shows me 42 minutes....

[Steve]

seems there is something wrong in the algoritme
maybe you two should post your firmware version of the OSTC to see if it is the same but I don't think it has something to do with the firmware but with the original algoritme written in C.

@Heinrichs weikamp: do you change the decompression algoritme in different firmwares or does this remains the same?

[heinrichsweikamp]

Hello,

In the 1.35, we have included some changes/fixes in the deco code, as well. I wonder if anybody had this issue with the new version already?

regards,
Matthias

[Olivier]

Hello, first dive yesterday night with 1.35 and everything went fine.

Regards

Olivier

[papamorse]

thanks for your answers. I'll try 1.35 soon (monday?) and wait & see

[ulrich]

Hello,

also discovered this during one of my last dives.
Everything went fine until I reached my 6 Meter stop.
Decosum shows something about 6 Min (1 Min at 6 and 5 Min at 3).
After reaching 6 Meter the decosum switched to 12 Min. Descending to 7 Mtr. and decosum switched back to 6 Min.
Seems there is some error or some rounding failure at the 6 Meter Stop.

Tested this using the simulator I could see the same behaviour with Firmware 1.38.
After installing the new firmware I do a reset all.

Settings are OC GF 30/90 using EAN28. Last stop at 6 Meter.

Ulrich

[Bradipo]

Ulrich, this is just a wild guess: do you, by any chance, have oxygen configured amongst the five gases with the "active gas" flag set?

The behaviour you describe looks similar to what the computer does when it expects a gas switch at 6 metres. I.e., below 6m it shows the time to surface needed if you switch to oxygen. If you do not, the time increases.

[Ulrich]

Hello,

maybe I have missed something
Until now my knowledge is that the OSTC only uses the current gas for decompression calculation. And in my opinion thats the correct way.
Until I have told him to use another gas he has to use the current
gas for his calculations.
If you are right I have to deactivate 4 gases if I want to make a
dive using only one gas. That sounds terrible?

Ulrich

[Antoine]

I understood so.

If you set a depth for your gaz ( 6 m for oxy), the ostc will take it in account for the deco.
You can easilly test if it comes from that by switching gaz after a deco increase.

The wiki page is laking of information or I did not see it.

Antoine

[Steve]

on the wiki you will find that active gasses are used for decompression calculation.

[Ulrich]

Hello Steve,

I have found it Shame on me. How could I miss this

After a first short test everything seems OK.

Thank you

Ulrich