Log import of Trimix dive from Shearwater Teric

Attilla de Groot attilla at attilla.nl
Sat Oct 9 12:54:30 PDT 2021



> On 9 Oct 2021, at 14:17, Robert Helling <helling at atdotde.de> wrote:
> 
> Hi Attila,
> 
> just quickly, as, surprise surprise, today I managed to get some diving done after more than a year!

Hope you had a great dive!

>> On 8. Oct 2021, at 20:49, Attilla de Groot via subsurface <subsurface at subsurface-divelog.org> wrote:
>> 
>> - When planning multiple dives, it is common to make variations (e.g 3min longer, 3min deeper) to determine gas usage. When planning them and moving around with dates, I sometimes get: " Subsurface (5.0.2.0) dive plan (overlapping dives detected)” instead of the Runtable. While that might be true, not really useful in planning mode. Adding these types of variations would be a nice feature to have in a single dive-plan btw.
> 
> You should plan these variations with the same start time. Then Subsurface understands they are different versions of the same dive. This is most easily achieved by planing the basic version of the dive and then save it to the dive log. Then you can reopen it via „Edit dive in planner“ from the log menu. There you have a „Save new“ button which does exactly what you want.

That is what I have been doing. Just creating multiple ones for each variation I would like to see.

> Actually, everybody has different opinions what kinds of variations (mainly depth and time) they want to plan. To come up with a user interface to handle all those  preferences would be almost impossible in a way that does not add a million additional options to the already quite baroque user interface for the planner. So we went with a minimalistic but very effective approach „plan variations (you need to check a box to turn those on). It outputs (in the planner notes) information like
> 
> Runtime: 83min, Stop times: + 2:45 /m + 5:57 /min
> 
> This means that if you change your depth (that of the last segment manually entered) you would have to add/subtract 2min 45sec per meter deeper/shallower  to the total deco time (usually proportionally to the already existent stop times). Similarly, you need to add/subtract  5min 57sec per minute that you extend/shorten your time at your last depth before ascending (in addition to the minute you stay longer/shorter).
> 
> This kind of information is usually sufficient to allow for some flexibility in your dive plan.

It is, I think valid for most dive planning. My main point however was the “overlapping dives detected” message I get when having multiple dive plans. I understand that everyone has their own opinions and it would be hard to satisfy all of them _and_ keep a lean interface at the same time. It was just a suggestion for a “nice to have”.

> 
>> - When planning a dive where you have a travel gas, you have to put that to “not-used” otherwise it will get automatically selected as deco gas (e.g when going down with EAN32). This is not desired from an ICD perspective.
> 
> I don’t know what an „ICD perspective is“. But making a gas „not used“ means exactly that the planner will not switch to it. You can still use it in the manually entered part of the dive.

When you dive with a Tri-mix with high helium, you typically don’t want to switch to something that has > 50% difference in nitrogen since that could cause ICD (isobaric counter diffusion). Selecting the travel gas as “not used” and manually using it is what I did now, but preventing something like this to be automatically generated would be of added value (although someone doing such dives should know better).


>> - There is a “Best MIX END” field, but it is unclear to me what it’s purpose is. What I do would like to know is what the END/EAD is for a tri-mix gas that I enter. If something like that could be added to the columns when a Tri-mix gas is used, that would be use-ful.
> 
> END and EAD are depth dependent (do not only depend on the gas). They are shown in the info box when you move the mouse over the profile.

I missed the box for it on the left. That shows exactly what I need. Thanks. :-)

> By entering a * in the column for MOD and MND for a gas makes the planner chose the best mix for the dive planned (with respect to O2 and He fraction). The "Best MIX END“ means that it choses the He component such that the gas is as narcotic at the deepest point as air at the "Best MIX END“ depth. Most people set it to 30m.

That is very useful. Didn’t know about that!

> 
>> - In planning I would like to know what my PPo2 is at a given depth of the dive. Is this possible?
> 
> Activate the O2 icon left of the profile and it is shown in the info box.

Same as above, I didn’t press the button ...

> 
>> - When using a travel gas, the first stop would probably be around 30-40 meters. Then the “drop to first depth” isn’t honored anymore for the next depth. Perhaps this thould be taken into account.
> 
> Again, make this such that it suits everybody will turn into a user interface nightmare. The „drop to first depth“ is a crutch anyway, all following waypoints have to be entered manually. Note that you have many options to do that: Enter values in the table of waypoints, double click in the profile, select a waypoint and use the cursor keys to move it around.

Fair enough. I thought it would be worth investigating an option where you could set a gas to “travel gas” and it would show you the depth for the change based on the END.

> 
>> 
>> In general though, the planning mode is quite good. We compared my result with the tools the instructor used and were almost identical (mostly rounding differences I guess). I hope that a planner can be implemented on the mobile version as well sometime, because it seems that there isn’t a nice one available for Android.
> 
> Currently there is nobody with enough time and understanding of the mobile UI to code it. But contributions are of course always more than welcome.
> 
> Actually, the first big obstacle is to design a user interface that is sufficiently expressive but lives the the confines of the mobile device (no mouse, very limited screen estate in particular compared to the typical finger size). Also here: Contributions welcome!

Unfortunately that is not my specialty. I hope someone comes around that does have the knowledge. Either way, in general I love the planner functionality.


— Attilla




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