Cobra anomaly

[John_ZAR]

Hi All,

I use a Vr3 and a Suunto Cobra (in gauge mode) for my diving, the Cobra is really only used as a SPG although I download the Cobra data to Suunto Dive Manager as I can keep track of my SAC rate of the back gas.

At 137bar on my back gas I switch to 53% at 19m for 18 min and then switch to 99% for 5 min. Therefore I am not using my back gas for 24 min yet when I review the graph in SDM of the dive, the consumption of the back gas continues until the end of the dive where I end up with 102 bar. That is a difference of 35 bar that I didn’t use. Other than it being a demon cave dweller hitching a ride to the exit without my knowledge I am puzzled.

The Cobra samples every 10 seconds and logs the data so therefore it would not / should not average out the gas usage over the dive but should show zero gas usage from when I switch.

Any ideas? and no there are no leaks.

 

[SuPrBuGmAn]

 

[John_ZAR]

That's not a demon cave dweller, as far as I can tell it's a transvestite trying to look macho.

 

[Cave Diver]

Therefore I am not using my back gas for 24 min yet when I review the graph in SDM of the dive, the consumption of the back gas continues until the end of the dive where I end up with 102 bar. That is a difference of 35 bar that I didn’t use. Other than it being a demon cave dweller hitching a ride to the exit without my knowledge I am puzzled.

The Cobra samples every 10 seconds and logs the data so therefore it would not / should not average out the gas usage over the dive but should show zero gas usage from when I switch.

Any ideas? and no there are no leaks.

What gas supply are you using for wing/suit inflation?

 

[John_ZAR]

I have an independent 2L for my suit and my wing is inflated off my back gas. That said I am ascending and then remaining at 18m so I would not be inflating my wing, maybe and this is a stretch, I use a little gas to get my trim correct but that wouldn't account for a 35 bar loss. I will, on my next dive, write down my back gas pressure when I switch to deco and then check the pressure of the back gas when I exit the water. I am assuming that this will be within my expected parameters and will highlight that the SDM program is the problem.