Features request : switching GF underwater

[smcmullan]

a) don't display the second GF pair - personally I could even live without it being configurable if it was set to 90/110 or whatever the "pure" Buhlmann algorithm uses

b) don't have a menu item - link it to the Bailout menu item instead

P.S. gorcio, hansjoerg - I hope my statements didn't offend you and I apologise if they came across like that. Late night internet use when tired is not good. I use the OSTC for everything from 12m air dives on single cyl open circuit to 120m CCR dives on 7/75 trimix. I honestly believe that the OSTC is an excellent compact and economic computer for all these uses and just because we're talking at the moment about a feature that is more aimed at CCR should not threaten the other users of the device. If the menu system is well designed and the features thought through carefully (which has been the case by HW to date) then there should be no impact on existing functionality.

[gorcio]

smcmullan Wrote:

> P.S. gorcio, hansjoerg - I hope my statements
> didn't offend you and I apologise if they came
> across like that. Late night internet use when
> tired is not good.

No worries, it takes much more to offend me. I hope I didn't come rude neither .
Agree, that showing second part of GFs not necessary. Deprivation of sleep made me think that Matthias wanted to display permanently the first ('normal' ?) set of GFs. Need to gulp some strong coffee

[scubatinoo]

DTR.Diver66 Wrote:
-------------------------------------------------------
> the display for the current GF-pair during the
> dive in the lower right menu, as average depth,
> future TTS and others. The ability to change over
> the top menu as gas list and Decoplan.

Ehm, sorry guys but why do you need an option to show the current GF-pair? I really hope that you know the values already before the dive and that you can remember it during the dive... An Option to change the GF's could be added to the menu in divemode (Gaslist, Decoplan ...)

[smcmullan]

I don't think we need it. Whats there is perfect. From memory pressing the right button will show the GFs, setpoint and diluent (and even last stop?). Perfect for checking before the dive.

[heinrichsweikamp]

How do we call the two different GF pairs? GF1 and GF2?

Regards,
Matthias

[DTR.Diver66]

Hello Matthias,

i would like GF and eGF for emergency.



Regards

[DTR.Diver66]

Hello Matthias,

another possibility would be GF and aGF for aggressive.



Regards

[heinrichsweikamp]

I think it's not necessarily more aggressive. Maybe "aGF" for alternative?

regards,
Matthias

[DTR.Diver66]

Hello Matthias,

i would also agree this (tu)


Regards

[swissdiving]

Stephen,

No offence taken!
I am not a CC diver and have no intention of taking it up (too expensive). Non the less I have no problem with adding a GF switching function during the dive mode.

Just the intial arguments, why a GF switch under water would practical or necessary, did not convince me the least bit. And I am still not entirely won over (not that it actually matters).

[DiverM]

Strictly speaking, when you have the GF displayed on screen, you can make a "linear-GF ascend" keeping the GF between 90 and 95 for example. And thus allowing for the of-gassing factor to be at a maximum at all times during ascend.

In an emergency you would then only have to take a few parameters into account: Gas, Rate of Ascend and the GF.

[garylegge]

I think the ability to switch would be a good thing and improve personal choice options. Following an emergency bailout to OC I wish to get up off the bottom quickly and as safe as reasonable. Therefore, when the computer is switched to bailout I would like the bailout computer readings to reflect my preferred ascent profile and not have to think too much about it. It'd be stressful enough as it is. If you're not going to use the computer to help you get up, why bother having it in the first place.

[heinrichsweikamp]

Hi,

switching the GF will be the next new feature we'll add. I think this can be interesting for many situations, not only bailout or emergencies.

Cheers,
Matthias

[smcmullan]

Thank Matthias. Can you give some examples of applications other than bailout or emergencies. I'm not very good with deco theory but certainly practice and observation

I thought the VGM algorithm from the VRx computer to be an interesting idea where you can select different GFs for different phases of the dive (deep, intermediate, shallow) and allow you more control over shaping the ascent curve. However I've never used a VRx. Did users use the algorithm to the best effect? Or did they just go for the default settings and dive? Interesting idea anyway, I'm just not sure how to apply it.

Again I'm weak on the theory but I believe Buhlmann assumes an ascent rate of 10m/min between stops. I've observed with myself that on CCR (where you can with a bit of experience observe your offgassing rate by how much your buoyancy changes as you offgas into the loop) that the *rate* of offgassing seems to vary at different points of the ascent and I changed my ascent rate to at times before heading up to the next stop. However that could be garbage - very hard to determine whether it is merely due to the shallower depth etc.

I asked Simon Mitchell at Eurotek '12 whether there had been any studies done on the effect of varying ascent rates for deep trimix dives on rich helium mixes and he told me that there had not.

So there's plenty of scope for computer modelling of decompression profiles both now and in the future in my opinion.

[wrobell]

maran Wrote:
-------------------------------------------------------
> hello,
> It would be good to have a possibility to switch
> gradient factor underwater. For example in case of
> losing the consciousness of my buddy I would like
> to go up on different settings than normally.

Why not simply set your computer to display low values
of GF (i.e. from 10%) and in case of emergency just follow
the value of displayed GF?

w

[dmainou]

wrobell Wrote:
-------------------------------------------------------
> maran Wrote:
> --------------------------------------------------
> -----
> > hello,
> > It would be good to have a possibility to
> switch
> > gradient factor underwater. For example in case
> of
> > losing the consciousness of my buddy I would
> like
> > to go up on different settings than normally.
>
> Why not simply set your computer to display low
> values
> of GF (i.e. from 10%) and in case of emergency
> just follow
> the value of displayed GF?
>
> w


Because you may have other things to stress about. I think it's better to have a pre established plan, put it in action and not hve to stress about following the GF in the first place.

D

[MeRodent]

Not that I'm against greater ability to customise to personal preference but I'm curious as to the need for adjusted GF for CCR bailout. CCR courses recommend (at least the TDI course does) carrying suffient bailout gas to complete BO from the dive right to point where you would ascend (highest on-gassing). Bailout is calculated from your RMV at stress with an additional 15% reserve unless team diving where the recommendation is for the team to carry 1.5 times worst RMV divers requirements. As such you will either have enough or have misscalculated the gas requirements indicating poor planning - at that stage is a changed GF really going to make enough difference?

[dmainou]

MeRodent Wrote:
-------------------------------------------------------
> Not that I'm against greater ability to customise
> to personal preference but I'm curious as to the
> need for adjusted GF for CCR bailout. CCR courses
> recommend (at least the TDI course does) carrying
> suffient bailout gas to complete BO from the dive
> right to point where you would ascend (highest
> on-gassing). Bailout is calculated from your RMV
> at stress with an additional 15% reserve unless
> team diving where the recommendation is for the
> team to carry 1.5 times worst RMV divers
> requirements. As such you will either have enough
> or have misscalculated the gas requirements
> indicating poor planning - at that stage is a
> changed GF really going to make enough difference?

I'm at work and can't really spend a lot of time on this but it is precisely a scenario like that that would require me to carry an extra bottle of bottom gas if I were to ascend whilst performing a number of deep stops.

In turn, I can get away with a reasonable setup by going shallow relatively quickly and staying longer at that shallow depth. I can even obtain the benefits of accessing the oxygen on my back. BTW this plan does include 5 minutes at the bottom on OC with a very high RMV. If the emergency isn't Co2 related then I most likely have enough gas to go up on the original profile.

I'm talking here changing from something looking 30/85 to something more plain buhlman like 90/90 or so.

BTW, I don't have the privilege of having a regular team. I know most people on the boat most of the time but can't/don't plan to rely on them. Therefore my gas calcs are made on the basis of getting myself out of trouble.

D

[wrobell]

dmainou Wrote:
-------------------------------------------------------
> wrobell Wrote:
> --------------------------------------------------
> -----
> > maran Wrote:
> >
> --------------------------------------------------
>
> > -----
> > > hello,
> > > It would be good to have a possibility to
> > switch
> > > gradient factor underwater. For example in
> case
> > of
> > > losing the consciousness of my buddy I would
> > like
> > > to go up on different settings than normally.
> >
> > Why not simply set your computer to display low
> > values
> > of GF (i.e. from 10%) and in case of emergency
> > just follow
> > the value of displayed GF?
> >
> > w
>
>
> Because you may have other things to stress about.
> I think it's better to have a pre established
> plan, put it in action and not hve to stress about
> following the GF in the first place.

well, after changing mode (if not wasting time, but i admit it is personal
preference) you will follow your computer anyway?

i would prefer bigger GF number on the screen. no need
to switch into some mode. the number is simply there.

the alternative GF feature comes like bumerang, so i suppose
it gets implemented, but i woukd vote for bigger GF number
display if possible.

w

[heinrichsweikamp]

When using a manual fast bailout strategy, displaying the ceiling (in m) would be more useful in my opinion.

As for bigger displays, the ability to read the standard font is essential. Otherwise we need to reduce the shown information.

Switching the GF can be interesting to compare standard Bühlmann with GF, for example. I think we'll upload a fresh beta tomorrow.

regards,
Matthias

[DTR.Diver66]

Hello Matthias,

still waiting for testing it. We are going to dive in the evening. Can we expect it before?


Regards

[Clownfish]

Is in lastest firmware beta