understanding TTS, with/with out deco stages

[petkozaric]

Hi again,

I need your explanation, how hwOS (which is in ostc 3) calculating TTS with or with out deco stages?

For example, When I dive OC with bottom mix 21/35 I always use gasses for accelerators for decompression (N50 and oxygen). I notice that on the bottom TTS is calculated only in manner that I use BT gas 21/35 .

Does it calculate TTS with or with out decompression gasses.
My opinion it does not take in consideration decompression gasses, because I notice that TTS start rapidly descent when I switch on first deco N50 and so on on Oxygen too.

I know that some competitor dive computer use calculation with deco gasses or not depend what we selected in option for deco gasses for proper dive.

Correct me if I am wrong, but I didn't find any explanation in user manual for TTS which is simple and very useful information for any type dive.

BR
Petko

[Ralph]

Hi Petko,

the TTS does take into account the deco gases, but in order to do so the deco gases need to be configured correctly:

1) they need to be set as type = DECO, and

2) they need to have their DEPTH set.

The depth setting determins the depth at which on ascent the gas is considered as usable. If the depth is set to 0, the gas will not be considered even if it is set as deco gas.

BR
Ralph

[petkozaric]

thanks, I understand know how OC setting works.

On the other side, how to setup correctly for pSCR?

We always start to dive with N50, like a first gas. On 21m we switch for first deep gas and so on.

N50 (N52) and Oxygen are use for deco.

[Ralph]

Hi,

your question has been anticipated recently and there is a major update in the handling of the first gas and the travel gases (aka "normal" for diluents / premixes) under way. But first of all, there will soon be a bugfix-version released (actually, its release is a little bit overdue) which is especially important for pSCR users. So please look out for update announcements here in the forum.

In the upcommoing version then, the first gas and the travel gases will also have change depths, i.e. depths set for these gases will not be cleared upon entering dive mode any more. So you will be able to set a limiting depth for your first gas, say 21 meters for your N50 set as type=first, and then have propper signalling at 21+ meters for another travel gas / normal diluent set to a deeper change depth.

While in the working phase of the dive, the OSTC will then always prompt for the best gas/dil among the first gas/dil and all travel gases (but not the OC deco gases!) / normal dils, evaluating change depths and ppO2 min/max limits. When entering the deco phase or when in bailout, the OSTC will search for the best OC gas among all gases, i.e. now including the ones set to 'deco'. For the diluents, working phase versus deco phase makes no difference as there is no type 'deco' for dils. The deco phase will be entered when reaching the first stop or whenever having selected a deco gas as the current gas.
In the upcoming version, the deco planning will also figure in diluent changes when in pSCR mode, so the TTS and the stops table shown in the custom view will then be based on gas switches as it is the case in OC mode since ever. Again, it is the configured change depths that will control the diluent selection then.

So you see, all means will soon be availale to tailor the best-diluent cues, the best-bailout/OC-gas cues, and the gas/dil selections inside the deco calculation exactly to your dive plan.

BR
Ralph

[ClaudeDive]

Very good news, great ... Thank you HW & Ralph

Regards,(tu)X(