Gas switching

[JeanDo]

Heiko Wrote:
-------------------------------------------------------
>... what's about the additonal time for gas
> switch, maybe colored ...

What would you dream of, for gas switching ?

Possibilities:
+ use CF55 (or whatever), for the number of minutes to ADD in decoplan, for gas switching, to the current stop. Nothing changes in the divemode or decoplan display (except the duration of stops, and TTS)

+ use CF55 (or whatever), for the number of minutes needed to switch gas: it will generate a stop at the switch depth, of at at least that duration. Nothing changes in divemode (except the duration of stops, and TTS).


+ Always use 1min for gas switch. If enabled (CF55 is a simple ON/OFF), then a line is inserted in the plan, as in:
[pre]
12m XX____ 3'
10m Gas #2
9m XXXX__ 10'
3m XXXXXX 30'
[/pre]
In divemode, nothing changes: juste the actual blinking * when changing gas.

+ Something else ?

[seawanderer]

I think it's good idea, but I'll always plan my diven with pc software

[ujacek]

> + use CF55 (or whatever), for the number of
> minutes needed to switch gas: it will generate a
> stop at the switch depth, of at at least that
> duration. Nothing changes in divemode (except the
> duration of stops, and TTS).

+1

or combination of extra (always added) and minimum time for gas switching (like in V-Planner), it requires one CF for the number of minutes and second CF for define: "add or minimum time".

Jacek

[Thom]

Yepp, gasswitchtime would be great!

Let me give you an excample for what that, what I think Heiko means.

First we dive OC!
So when it comes to gasswitch the OC divers stay a few minutes on the switching depth. (5 minutes or so)
Because we don't dive with constant PPO2 (like the CCR guys ) We have to care about the stop time a little more (Oxygen window, get the body used to the new gas)
For example: You come from the depth to your first gasswitch on 21 meters to Nitrox 50/xx.
If the ostc shows a stop on 21 Meters for 1 minute and you stay a little longer (3 to 5 minutes) the decoplan shown on the computer will change.
So far so good BUT, I would like to tell the computer, that I'm going to stay this extratime on the gasswitching depth BEFORE the dive. So I know BEFORE the dive (via Simulator) how the deco is going to be.
This would be my biggest wish for the future development on the ostc.
It would be a great thing for us OC divers.

Cheers
Thom

[Heiko]

Hello community,

exactly as Thom explained. And in addition, we do not need to handle with the stopwatch during the gasswitch, if everything is going well. This is what OC divers (or myabe just some) are doing on stops with gas switch. Taskload reduced.... more time to watching the cave, or the fishes...

my proposal: additonal gas switch time, more for the time to get the gas into the blood, on top of the stop time calculated.

minimum time from my humble opinion is not right, it would not include the time if the stop for example is 5min to stay (w/o gas switch time), minimum is set to 2min. I would prefer to have the 5+2 min => 7min.

Looking to vplaner, additional stop time is possible just on the stops below 6m,
and even it could be different between 7-30m and 30m+, so no additonal time on the switch to oxygen. If we compare we should do it right .

But always as seawanderer said: Plan your dive, dive your plan, OSTC is just monitoring and makes the dive more exiting.

I like the proposal of Jacek. It keeps the freedom for everyone.

Cheers

Heiko

[Heiko]

Hello Jean-Do,

just to make sure we are on the same idea: it is not only to add additonal time on top of the time the algorithim is calculating at the depth of gas switch and thats it. The calculation of all other stops above or after the gas switch has to be based on the extended time calculated.

Normaly the longer stay for example on 21m with 50/xx should reduce the stop duration of some stops above, espacially the stops on 3m w/o oxygen and the 6m with oxygen.

But maybe that was already your idea.

Thanks a lot for start working on this wish.

Cheers

Heiko

[JeanDo]

@Heiko

Sure ! Actually there is no real choice: Because computing the decoplan is just running some fast ascent simulation, any gas-switching-stop you add will automatically change all the stops later on.

In that sens, the > does not ring anything for me. This is just a sentence that describe exactly what gas diffusion model at the basis of the Buhlmann model indent to calculate...


Not sure I made clear my minimum proposal: 5 min switch + 2 min stop = 5 min total
And of course: 5 min switch + 13 min stop = 13 min.

I still don't see why you would like to do: 5min + 2min = 7min....
In particular with deep gas switches, it will add gas loading in medium compartiment... Just as a too high GF-low is not good...
--> Can someone enlighten me ?

[JeanDo]

Heiko Wrote:
-------------------------------------------------------
> [...]
> Looking to vplaner, additional stop time is
> possible just on the stops below 6m,
> and even it could be different between 7-30m and
> 30m+, so no additonal time on the switch to
> oxygen. If we compare we should do it right .

Do you mean you would dream of two (or three) different CF just for gas switching time in the 3/6/9, 12..30, and more than 30 meter ranges...
I would fear too complex settings will lost everybody...

[Heiko]

Hello Jean-Do,

you are right, haveing two CF it would be too complex and I do not see really a benefit. This was not my proposal, just to tell you what the vPlaner is doing, as an example.

But coming back to your minimum proposal.

lets take a dive as the basis for the disussion, an easy one:

45m 19min, TX21/35 + EAN50, GF10/80.

You get a stop on 24m 1min, 18m 1min ...etc.

But in reality we are stopping also on 21m, switching gas and staying for 3min.

so there is always a stop on the depth of the gas switch, in OC.

If you play a little , sooner or later you get also a stop on 21m maybe 1min.

But even in this case I stop 3min.

This is exactly what I would see in the decoplan.

In case I have to stop at 21m 5min by the gas model, I will add the 2min on top, and this what I do so far planning the dive with vplaner for example.

So, I'm looking for additional stop time on gas switch and again I like the proposal with an addtional CF to switch between minimum and additional stop time.

Or maybe we start within the next beta with minimum.... better than nothing.

Community, please help

Cheers

Heiko

[ujacek]

Heiko Wrote:
-------------------------------------------------------
> Hello Jean-Do,
>
> you are right, haveing two CF it would be too
> complex and I do not see really a benefit. This
> was not my proposal, just to tell you what the
> vPlaner is doing, as an example.
>
> But coming back to your minimum proposal.
>
> lets take a dive as the basis for the disussion,
> an easy one:
>
> 45m 19min, TX21/35 + EAN50, GF10/80.
>
> You get a stop on 24m 1min, 18m 1min ...etc.
>
> But in reality we are stopping also on 21m,
> switching gas and staying for 3min.
>
> so there is always a stop on the depth of the gas
> switch, in OC.
>
> If you play a little , sooner or later you get
> also a stop on 21m maybe 1min.
>
> But even in this case I stop 3min.
>
> This is exactly what I would see in the decoplan.
>
> In case I have to stop at 21m 5min by the gas
> model, I will add the 2min on top, and this what I
> do so far planning the dive with vplaner for
> example.
>
> So, I'm looking for additional stop time on gas
> switch and again I like the proposal with an
> addtional CF to switch between minimum and
> additional stop time.
>
> Or maybe we start within the next beta with
> minimum.... better than nothing.

... and better than always added time.
I prefer minimum time for gas switching. This is a sufficient solution for me. My proposal with second CF as option between minimum and extra time is probably more universal and is a way to avoid dispute "minimum time or additional time".
Jacek

[Heiko]

Good Morning,

+1 for the minimum (as an appetizer).

But finaly I have to give you a real good reason for additional time:
Some of our last cave dives came into my mind (my favorite buddy ):
If you do some deeper penetration, you normaly leave the deco stage at the deco depth. We are breathing out of a stage, on the way back we are switching from stage to back gas, move the stage away, picking up the deco stage and switching from back gas to deco gas.

This is additional time at the deco stop on the gas before switching to the deco gas. Around 2min...

But maybe this is then the advanced version, not usefull in openwater dives.

Cheers

Heiko

[Thom]

Moin Moin ,
to make a Long story short.
In todays decodiving(OC!) it is essential to give the body some time after a gasswitch to get used to the New gas and to have the maximum profit of the gasswitch. Typical we have around 3 to 5 minutes. The switchingdepth for the most dives is 21 meters. we switch from bottomgas to nitrox 50/xx.
The most OC diver dive this today.
So it would be very helpfull to tell the computer bevore the dive that we are going to stay at 21 meters for lets say 5 minutes.
So you could see when you plan your dive what the deco is going to be BEFORE the dive.
Yes, we plan our dives on computers or smartphones. And I like to see the same profile on my ostc.
So is it possible ( via CF) to set a stoptime just for the gasswitchstop on 21 meters??
Then I could plan my dive, check it with the simulator and execute the dive like planed.
Don't get me wrong. I love my ostc. Even hardcore bottomtimerusers asked me to check it. With the gasswitch/stoptime it would be perfect for me.
Looking forward to an exciting caveweek with my favourite buddy

cheers
Thom

[Zyrus]

+1

[Uwe S.]

Hello JeanDo,

i like: + use CF55 (or whatever), for the number of minutes to ADD in decoplan, for gas switching, to the current stop. Nothing changes in the divemode or decoplan display (except the duration of stops, and TTS)

I want to add the minutes myself. Minimum 1 min up to 5 min max and no changes in decoplan. I spoke to a lot of people at the boot show and they all think the same. I hope you do it so.

Best regards Uwe

[Tom]

I dont really get these remarks. In the dive you know you are going to stop 3 minutes or so at the switching depth. So you add 3 to your runtime and thats it.
To do your planning you know it also. So i dont realy see the problem.
What i see on this forum and what i personally dont like is that ppl are requesting features that are of little bennefit (in my opinion) to the REAL picture, but that are making it more difficult to extract a minimum decompression obligation from the machine. So they are actually making the machine less usefull, not more usefull.

[Thom]

Hello Tom,

let me just remark a few things.
1. What a diver needs / wants is differing. I don't think our suggestion is only for a few divers. Almost every diver (OC!!) is lengthening the stop after a gasswitch. I don't want to explain the reasons here.
2. It is not just adding a few minutes to the stop. It affects the time of the shallower stops! It's about decoquality not only duration. I like to know how my deco is going to be. I like surpises, but NOT with deco!
3. What makes the machine usefull or useless is very individual. Therefore we suggested to add a CF which you can use or not. (Believe me I know a lot of guys who would set the 21 meter stop to a longer period)
I personaly don't need coloured gas symbols (I know which gas I'm diving), END/EAD
(I know which gas for which depth to use), I don't need a leadtissue (I don't care)
and I don't need an altimeter. CF Espressomachine would be fine.
But everyone who likes it can switch it on.
That's why this computer is so great (and the display of course, I'm getting older)
So that's what opensource is about.

Thank you HW Team for doing such a great job!

just my2cents
Cheers Thom

[Heiko]

+1 and an additional +1 for Thom.

[JeanDo]

Summing up:

I'll add a CF55 "Add Switching Time"

- Defaults : 0 minutes --> no change.
- Max 5 minutes (btw, it only goes red if > 5 min, nothing else).
- During ascent simulation (ie. both decoplan and divemode), will be added[sup]1[/sup] to every deco stop[sup]2[/sup] where the OSTC proposes a gas switch.
- The TTS and decoplan will show the stop with that extra-time added.
- The extra time will be simulated too: so it will change[sup]3[/sup] shallower stops.

Correct ?

Notes:
*1 : Actually adding is easy, mininum is more tricky to implement, so let start with just add.
*2 : Easier too to check just at stop depth...
*3 : Note that adding 5min at 21m for short/shallow dive might AUGMENT shallower stops (probably uncommon btw).

[Heiko]

Hello Jean-Do,

correct.

Note 3: I call it dive planning. If needed, add additional time, if not 0 min. Short or shallow dives do need a deco gas, maybe.

Looking forward to 1.81.

Cheers

Heiko

[JeanDo]

@ Heiko, Thom, ujacek:

I have some prototype running. Email me if you want to have a look at the traces.

Cheers,

[heinrichsweikamp]

Hi JeanDo,

Just a small test with comparisons to the 1.7 and 1.8 stable and I'll upload the beta today... In French and English

Cheers,
Matthias