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Better Gas Change
Posted by: mobu ()
Date: April 14, 2019 10:54PM

Hi,

Today I've made a dive and on the ascent, when I get close to the configured change depth of the gas,my OSTC did not suggests me the appropriate gas.

It's strange because it has always worked, but not this time. I have changed by entering the menu.

What can be caused this?

I do not remember making any changes to the OSTC set up.

My Gas Set up was:

Gas1: *Air (White letters)
Gas2: =Nx50 (White letters)
Other gases disabled (Blue letters)

I also noticed that from v3.01 version, there is a sing = before the deco gas. What does this mean?

Thanks.


Regards.

mobu

OSTC plus #16088

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Re: Better Gas Change
Posted by: Clownfish ()
Date: April 15, 2019 11:49AM

I also had this happen on the only dive I used after 3.01. I double checked all settings were correct.

Michael
Sydney
Australia
OSTC 2 11528

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Re: Better Gas Change
Posted by: Ralph ()
Date: April 15, 2019 06:58PM

Hi,

this topic had already been raised a few days ago, see [here] and also [here - German language only].

Short summery: following recent study results on the effectivity (or not) of deep stops, the "better gas" cue has been aligned with the deco calculation strategy that computes the deco schedule. The strategy is to calculate the shortest (overall time / TTS) and least gas consuming deco schedule that fullfills the Bühlmann model, with GFs applied when selected. So ascending to the first stop has been given priority over switching gas, which would be a "switch on the fly" with no required stop at the depth were the gas becomes available by ppO2. Sure one can do this, i.e. picking the gas via the menu, but the OSTC will not come up with a blinking cue while still in the ascent towards the stop.

Calculating a "switch on the fly" could deliver an improper deco prediction when that switch is not done, e.g. because the ascent is done on reel and SMB keeping both Hands busy. Instead it is assumed to be done when arrived and stabilised at the stop. It's also in line with what Multideco does unless you activate "Extended stops" and "all deco stops".

Ralph


PS: = means it's a deco gas, imagine the lines being stop depths. * remains the mark for the gas set as first. A gas without anything is a travel gas. If the whole gas is printed in inverse, your're on an OSTC TR and that gas has a transmitter paired with it.



Edited 1 time(s). Last edit at 04/15/2019 07:22PM by Ralph.

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Re: Better Gas Change
Posted by: ClaudeDive ()
Date: April 16, 2019 11:59AM

Hi

... And "X" in front of inactive gaz thumbs up

Regards

ClaudeDive ><)))))°> OSTC3 #2430 <°(((((><

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