question about the semantics of adding a gas change

Henrik Brautaset Aronsen subsurface at
Mon May 11 23:12:08 PDT 2015

On Tue, May 12, 2015 at 1:39 AM, Dirk Hohndel <dirk at> wrote:

> It feels like we talked about this before. But after playing around with
> both the planner and the dive editor for a while I'm not sure I like what
> we do (or, frankly, fully understand what we do).
> So let's enter "add dive" mode. A very basic profile shows up.
> Now add a second tank with pure oxygen.
> Click on the handle at the beginning of the safety stop and try to switch
> to pure oxygen
> (right click, context menu offers AIR and OXYGEN, select OXYGEN)
> No error, no nothing, doesn't work.

Same here.  That's completely bonkers.

> OK, maybe there's some magic to keep my PO2 in a safe range, but no
> message?
> Next attempt, change the tank to EAN80
> Again, right click on the handle at the beginning of the safety stop (at
> 5m). Pick EAN80
> Now the ascent from depth to 5m is using EAN80 and there (at the node I
> clicked on) we switch back to air. Not exactly intuitive. And of course
> this means that I cannot actually end the dive on a different gas than I
> started with.
> But quite frankly, why DOES it change the previous segment.

Bonkers again!

> If I click at a spot in the profile in normal view mode and add a tank
> change then the gas from that point on changes. That seems to be the
> logical thing to do. Yet here we change the gas used during the segment up
> the point we are on.
> Can someone explain why this makes sense?

It doesn't!

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