Blackwood:
That didn't really answer my question about how you deal with changing paradigms.
Say you are on a somewhat deep rec dive. Your primary computer's algorithm credits you for deep stops. This computer fails mid ascent and you bail to your backup, a buhlmann model which wants to push the gradient and thus dings you for your deep stops and jumps into obligation mode. Do you listen to it and hang shallow until your drain your tank? Or do you use your "clue" and continue the dive with a reasonable profile?
If you listen to the backup, why isn't it your primary? If you continue ascending in the manner suggested by the failed primary (which I hope is an algorithm you have faith in), what's the backup for?
If don't see any redundancy if you can't simply switch seamlessly from one to the other.
Note: my question involves algorithms, and thus computers set to gauge mode aren't considered "backup computers" in my questioning.
Well, my primary is either cut tables or a VR3 depending on the profile. We'll go the VR3 for a simply rec dive. My backup is Bulmann tables and a BT.
Now, lets say the profile was this: 120' for 25 min, I was doing a deep stop at 70' and the VR3 dies. Good enough scenario? (I know its slightly outside of rec but it would cause deep stops on the VR3)
My procedure. Whip out my handy dandy buelhmann tables and see where I am at. Assuming I am on schedule, I'd do my next 'deep' stop around 40' and finish the schedule called for by the tables for a 25 minute run time. I'd also extend the 20ft stop by 3-5 minutes, especially if I had O2. As for how I knew the schedule, I watch that during the dive and even if it failed, I can estimate where deep stops should go and for how long.
As for gas, I plan all my dive with 1/3rds or rockbottom. I have the gas to do the dive. I also have a fully equipped team mate to assist.
Now, did I follow the tables to the T - Nope. I don't always follow the VR3 to the T either (some deep stops it wanted have been at an inconvienent depth). Its a tool and I have to agree to the profile and information it gives. No blind faith.
If I backed it up with a computer, I'd follow it as well but still do the deep stops. The computer may not require them but my dive plan does. Again its a tool to give me information. I decide whether the profile it spits out is good or garbage.
In reality, my backup is there to give redundant time, max depth and current depth information. Assuming a pure rec dive, you ascend and surface at any time right. What would a different computer matter. Do a 3 minute safety stop and go from there.
If you are pushing it a bit, like the profile I described above, you should have the training to do it and plan bailouts. Even at the Adv. Nitrox level, if you dive within your training level, you should have 15 minutes or less deco right - do your 15 minutes at 15-20' and surface. Between you and your buddy, if you planned your dive, you have the gas to do it. Beyond Adv Nitrox, you ought to know enough to get yourself home from your dive plan.
