Gas cont. and GF in BO in CCR mode

[mobu]

Hi,


I have two question, both of them in CCR mode:

- When I want to simulate a dive, in the menu calculator setup I have three options. I don't understand gas cont. meaning.

- In the same menu I have use aGF. Whether you choose it or not, the calculator uses the GF for both parts of the dive. The CCR part and the part where you switch to BO. However, my AP inpiration computer does not let me continue with the same GF as in CCR when I switch to OC. I can choose another GF but more conservative (the manufacturer gives several reasons but it is not the subject of this post). The question is if in my OSTC+ I could choose two different GF values when doing the simulation. The normal GF for CCR and the aGF for when doing the BO calculation.

BR

Ion

[Ralph]

Hi Ion,

For the deco calculator:

1) "gas cont." = gas contingency. When the OSTC computes the gas needs for the BO ascent, it may happen that more volume of a certain BO gas is needed than available as of the current tank settings. If this option is activated, the OSTC will switch to the next best BO gas (that certainly is less effective) and calculate the remainder of the deco with this alternative gas before a stop depth is reached for which a new untouched-so-far gas becomes available. So the OSTC will mimic what you will do during an emergency BO ascent on marginal gas reserve.

2) During the bottom part of the dive, regardless if OC or CCR, the GFs do not matter yet. They only come into action when calculating the deco stops. So in "real" diving, your Inspi as well as the OSTC run on a certain pair of GFs to continiuously calculate the current deco plan. But in OSTC calculator mode, this does not happen, the calculator just keeps you at the set bottom depth for the set time to build up your deco obligation, and only then starts doing the ascent caclulation. So the GF selection here influences the resulting deco stops calculation only, but not the initial deco obligation.

In simulator mode, you can toggle the GFs via the menu as if you would do a real dive.

BR
Ralph

PS: i would opt for more convervative GFs while in CCR mode as length of the dive => available gas volumes is not the key limiting factor. But in BO, when gas reserves may become marginal, i would rather have my OSTC to calculate a faster ascent. If gas reserves look good, i can always pad the stops as a like, but the other way around i may run out of gas at 6 meters or so...

[mobu]

Hi Ralph,

thank you very much for your quick reply. Well explained and understood.

[quote]PS: i would opt for more convervative GFs while in CCR mode as length of the dive => available gas volumes is not the key limiting factor. But in BO, when gas reserves may become marginal, i would rather have my OSTC to calculate a faster ascent. If gas reserves look good, i can always pad the stops as a like, but the other way around i may run out of gas at 6 meters or so...[/quote]

This is not the reason for my item but what you say is the same as what the manufacturer answered me when I asked why the GFs were not very conservative in case of BO.
In case of problems it is better to leave as soon as possible and not get the risk of running out of gas. If you have enough gas when you reach the last stops, you can always extend those stops and get out more safely.

I'm glad to hear that you think the same way.

BR
Ion

[Ralph]

:-)

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