dive planner update

Dirk Hohndel dirk at hohndel.org
Thu Jun 27 06:07:24 PDT 2013

On Thu, 2013-06-27 at 15:00 +0200, Robert Helling wrote:
> On 27.06.2013, at 14:51, Dirk Hohndel <dirk at hohndel.org> wrote:
> Dirk,
> > I think for the part of the dive profile that the user enters we should
> > not enforce standard vertical speed. Your code does something that I
> > find quite unintuitive. If I enter a point at 4 min / 10m then I believe
> > Subsurface should show a slow descend to 10m over 4 minutes. Not an
> > extremely rapid drop down to 10m and then 3:40 at 10m. If that was what
> > I wanted, I would have entered a first data point at 0:20 / 10m.
> I think that's a matter of taste. And of course, you are the boss.

No - I'm the maintainer. Linus is the boss :-)

More seriously - on many many issues I am more than willing to listen to
strong preferences from other developers. So if people think that your
solution is better, by all means, please speak up.

> But in my experience, in the large majority of the cases people would
> use a planner, the plan would be something like "Let's plan a 30minute
> dive at 35m". And I think this should be easy to enter (i.e. require
> only one click). That's at least how I usually think of my dives, even
> for shore dives: Go to some depth and stay around there for some amount
> of time (e.g. until my computer shows x minutes of deco). Then ascend,
> possibly not at the maximally possible speed but usually I start by
> going to max depth first (and reasonably fast) and then work up from
> there. 

Interesting. What do others think... is that the preferred way to use
the planner?

For the tec dives I do we have a rather slow slope so going down to 60m
even along the fastest path will take you about 7min (unless you have a
scooter). So for me your algorithm not only wouldn't make things easier,
it would even make it impossible to plan my dives correctly (as you
would have me at 60m after only 2 min which will create significantly
more deco - and no way to change this).

> Needless to say, that does not fit all cases and having a more general
> descent should be possible but I would opt for the other as default.

How would the user switch? In an easy to understand, user friendly
fashion? While your way is more convenient for some I think mine is more
consistent for all. But if we can come up with an easy way to start with
yours and then being able to intuitively change to mine...

How about this... adding a node at say 60m / 7min inserts TWO nodes. One
at 60m / 2min (Robert "drop like a stone" Helling point) and the one
that they user actually entered. And then the first one can be manually
moved around and once an automatically added node like this has been
moved the vertical speed is no longer enforced.

Of course this creates its own set of potentially inconsistent


More information about the subsurface mailing list