Cobra air time calculation

[Aegir]

Does anyone know how the cobra calculates the airtime based on your air consumption rate. How can it do this if you are constantly adding and releasing air from your BC/Dry suit during dives, especially multilevel dives.

 

[Warhammer]

It calculates air time remaining by determining your current consumption rate. It updates itself frequently, I forget just how frequently. But adding air to your BCD, purging your reg through the purge button, free flowing the reg, and etc all have an effect on the air time remaining calculation. So if your purging your reg the air time remaining calculation will be incorrect until you stop purging and the cobra updates its calculations. Just remember that the calculation is always based your current air consumption/conditions and if those conditions change, then so will your air time remaining.

 

[Rick Murchison]

The Cobra air-time algorithm is also biased toward the short side - that is, if you use a lot of air it will quickly recalculate your air time based on the increased consumption rate (a freeflow, for example, will bring the air-time calculation down dramatically and quickly), but it is slow to add time as you decrease your consumption rate. This is a bit of conservatism the designers felt it wise to include... they felt it was much smarter to err on the short rather than the long side.
Rick

 

[Aegir]

Thankyou for your help guys

 

[The Chairman]

Hey Aegir & all,

What they said... ;-) They are on the money, the cobra uses a worse case scenario and has no way of knowing HOW you used your air (breathing it or filling your BC) so it averages the whole dive... on the conservative side. You can also program to what pressure your dive should end, and it will make its predictions to that. IE if you set your end point to 500 psi, you have 0 min remaining when you have 500 psi in your tank.

Pete from Orlando...

 

[Aegir]

netDoc are you sure about that?

I didnt know you could change the 0 airtime ...could you perhaps explain how please since i cant find it in the manual anywhere : / Cheers

 

[The Chairman]

Yes it is true, the only way to change it to use more air (grin) or to change your "Safety profile"... Either way, apparently the lowest figure used will be 500 psi.

Pete from Orlando...