Subsurface minimum gas calculation - First version for review

Stefan Fuchs sfuchs at
Tue Feb 14 11:50:21 PST 2017

Hi All,

Joachim (R.) and I finished our first basic version of the minimum gas
calculation for the planner.
We are now looking for testing and feedback :-)
More details below...

Link to initial idea and discussion:

Link to feature branch on Github:

My feedback to comments from Robert and Joachim (B.):
- Increased deco for longer bottom time due to problem solving time: No,
honestly this would have been much too complex for me at the moment.
Also this would not be according to how I would even handle it during a
real dive. But this may be a longer discussion... ;-)
- Real gases: Yes, hopefully implemented correctly.
- No hard coded SAC*2: Yes, good idea, we didn't do this but for the
moment I limited SAC factor to min 2.0/max 10.0. 2.0 would be two divers
with unchanged SAC. SAC factor of e.g. 4.0 would be two divers with
doubled SAC. BTW: Setting problem solving time to 0min comes close to
"disabling" the feature.
- Support rec dives: Yes, clearly, calculation is active for all OC
dives. I put some limitations for min depth (>18m) and min tank size
(12l). Calculating minimum gas for smaller cylinders is from my point of
view almost useless.
- Calculating problem solving time as result: No, this would not fit
with my idea of doing and using it.

Open questions:
- Most important: Any huge mistakes? Do we screw up ;-)
- What is missing? What else will we need to do? E.g.:
    o Everything ready for translations?
    o Which documentation would be mandatory?
- Any dive setups where this should work but doesn't based on this
implementation? Remark: It is clear for me that this implementation is
currently only useful for limited types of dive scenarios.

Possible enhancements I still have in my mind:
- Print such a tiny little yellow warning flag in the profile when
minimum gas is exceeded before end of bottom time. Anyone could guide me
how to do this?
- Tooltips for the new preferences. I can easily do this. One question:
What about line breaks in tooltips? Good/not good? How do they work?

Best regards


Stefan Fuchs
E-Mail: sfuchs at <mailto:sfuchs at>

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