Dive import - too long

[alpheios-one]

Version 1.7.5.6211

The dive computer records for a few minutes after surfacing.

When CCR diving with your CMF (Constant Mass Flow) and a pressure sensor on the oxygen cylinder, the following happens.
The cmf allows oxygen to enter the device continuously, a constant small feed.
When the dive is finished, the oxygen tank is closed on the surface.
The residual pressure in the hose is still dissipated via the cmf.
Because the dive computer is still recording, it leads to the air consumption being set incorrectly.

The value should be taken over immediately after it appears.
By this I mean, if I read out the computer with Bluetooth then the gases are automatically selected / tank is added and the last pressure is taken over.
Here he should take the pressure immediately after surfacing it.

[ericgriffin]

Thanks for reporting this. The cause is exactly what you described. The end pressure we import is the one the computer reports, and that value is simply the last pressure sample in the log. There is no check for whether the diver had already surfaced, so on a CCR oxygen cylinder with a constant mass flow orifice it lands deep in the post-dive tail and your oxygen consumption comes out far too high.

Fixed in #1290. Cylinder end pressure is now read at the moment of surfacing, which we take as the last sample deeper than 0.75 m, rather than at the end of the recording. Each cylinder is handled separately, so on your dive the diluent keeps its 136 bar and only the oxygen is corrected, back to 41 bar.

Two things worth knowing about how carefully it applies:

• It only corrects a value when it can show that value came from the post-surfacing tail, and it never lowers an end pressure. A computer that works out its end pressure some other way, or a transmitter that dropped out before you surfaced, is left alone.
• The dive profile itself is untouched. The tail stays on the chart exactly as your computer recorded it, so nothing is hidden from you.

Once this reaches a build you have installed, you will not need to download your dives again. Open an affected dive, use "Reparse raw data" from the overflow menu, and it will re-read the stored raw bytes from your computer and correct the tank pressure in place.

There is also a switch under Settings > Data called "Tank pressure at surfacing" if you ever want the raw last reading back. It is on by default.

This is not in a released build yet, but it should be in beta shortly and in stable v1.7.6.