[Subsurface-divelog/subsurface] Recreational dive planner (#262)

[Jan Mulder]

For completeness also here:

(sorry for the bottom post).

--jan


On 19-03-17 11:26, Stefan Fuchs wrote:
>
> Hello Jan,
>
> Am 19.03.2017 um 09:53 schrieb janmulder:
>>
>> Ok, I never use the Subsurface planner IRL so I might be confused how 
>> thing are supposed to work. So when working on a translation of the 
>> user manual (to Dutch), I sometimes find functionality that I just 
>> try on the current master.
>>
>> Intrigued by a sentence in the user manual "/Subsurface/ will 
>> automatically extend the bottom section of the dive to the maximum 
>> duration within the no-decompression limits (NDL)." from the 
>> Recreational dive planner section, I try to plan a recreational dive 
>> following the procedure in the user manual. I expect to end up with a 
>> dive with at least reserve pressure, with a maximum bottom time 
>> without any deco obligation.
>>
>> It is unclear to me how to trigger the "automatically extend the 
>> bottom section". It lets me drag the waypoints, sometimes I see a 
>> minor snap to a different value, but, in general, this does not lead 
>> to a bottom phase on NDL. Tried to drag points, alter the table, but 
>> to no avail.
>>
>> Seems a bug to me.
>>
> I was in a similar situation a few days ago when I had to decide how 
> to implement and document the minimum gas calculation for the planner:
> I also had to learn how the recreational mode really works - I never 
> used it before.
> But my result was that after the idea became clear to me and I double 
> checked a few results by e.g. calculating gas consumption I felt very 
> happy with the results and started to like the implementation. So no 
> bug found on my side.
> One hint: As soon as you use such tiny small cylinders like 10l <g> 
> most probably gas consumption and reserve gas will be the limiting factor.
>
> BTW: I copied this to the mailing list.
>
>
> Best regards
> Stefan
>
> -- 
>
> Stefan Fuchs
> E-Mail: sfuchs at gmx.de <mailto:sfuchs at gmx.de>
>

Ok, ok. Like I said, never user de planner IRL (and certainly not in 
Recreational mode).

As Stefan pointed out on the mailing list ... it takes a little training 
to get familiar with use the planner, and indeed, I know do not see the 
issue I pointed out here any more.

I understand where I was thinking the wrong way. I had set slow ascent 
speeds, and did not really notice the change of scale of the entire 
window when changing data of the profile. What is still counter 
intuitive for me, is that it is called recreational dive mode, but 
taking into account slow ascend speed (3m/min from 50% up, 1m/min from 
6m) you still can achieve TTS values of 20 minutes (for a dive to 30m). 
The counter intuitive part for me is, that I am not aware of any 
recreational dive courses that take into account different ascend speeds 
depending of depth. Obviously, this is something very well known in the 
technical diving scene. And TTS of 20 minutes can hardly be considered 
recreational.


Issue closed.

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