Predator/Petrel lost gas procedure ?

[sea_ledford]

While doing recreational "non-deco" dives, I'll run my predator up to a few minutes of deco because it goes into deco so fast (running 30/70 GF). I'll keep an eye on my TTS, and once it is up to 5-7 minutes, I'll call that dive done and head up. I'll still be the first to NDL out as compared to divers running Tech 2Gs though.

If I were to leave on deco gasses that I don't have, that plan would be royally screwed, aside from the fact that I have a pretty good idea of how long a dive can be at a given depth without going into deco.

On the Predator you can't turn gases on or off though. If it is programmed in, it's on. So it actually makes it pretty easy to check if you have incorrect gasses on. It also doesn't have the fancy nitrox mode that would probably eliminate the need to do this, but I've yet to use one in that setting, so I don't know.

 

[Dr. Lecter]

On the Predator you can't turn gases on or off though. If it is programmed in, it's on.

That is definitely not universally true. What firmware are you running?

 

[ajduplessis]

I had a (sold) Predator and was able to switch gasses on or off throughout the various firmware versions. I believe my came out with V42 and the last version i loaded was 46 I think.

Someone asked about diving 2 shearwaters and ditching a run/slate. I would do this without givng it a second thought, I just cant justify the expense for 2 Petrels.

 

[Dr. Lecter]

I've run two Petrels on OC before, and ran a Petrel/Predator controller on my rEvo...but for dives where deco obligations are measured in hours and hours of time, bringing only two sources of information and running identical hardware/software at that. I'm still bringing an analog depth gauge, watch, and cut tables as an absolute last ditch backup. Then again, I don't do buddy diving for tech until non-team bailout becomes physically unmanageable, so I'm assuming self reliance in a worst-case scenario.

 

[steady1570]

I don't know anybody that would do a single-tank rec dive with enough depth and enough bottom time to rack up enough deco on enough mixes for it to matter.

Agreed, but even if there is no deco showing on the computer (ie TTS is just 2-3 mins), that’s assuming you are changing gasses, whereas only on air it could well be different. Perhaps not too dangerous, but still...

Nothing replaces proper planning, agreed, but at what point is it "kosher" to run two Petrels instead of cutting tables? The Petrels will do the same work as your deco program on your computer, but in real time.

I trust the computers on my wrists every bit as much as the program on my desktop, but the problem is always in the planning - ultimately how much gas do you need. I think that’s the part that needs to be done on software before you splash. So for a typical ccr dive (some deco but not pushing my personal boundaries) I will plan on a desktop, mainly for bailout purposes, but not actually cut any tables, but instead rely on the predator controller and petrel standalone to run my deco for me in real-time as you say. If I am going to be pushing into new areas of diving (depth, time, location perhaps), then I’d have at least bailout tables in my wetnotes, but that’s not a standard dive.

As I gain in experience I’d hope that I’d start to have a feel for what the “right” deco is naturally. Ratio-Deco for example is a concept that I would like to learn more about, although I do wonder how effective it is on CCR (I really know very little so it may work fine), and more importantly if I find myself in a situation where both computers have failed and I’ve probably bailed out, will I trust my brain to do some reasonably complex maths…. But it’s better than knowing nothing perhaps

-Mark

 

[ajduplessis]

I've run two Petrels on OC before, and ran a Petrel/Predator controller on my rEvo...but for dives where deco obligations are measured in hours and hours of time, bringing only two sources of information and running identical hardware/software at that. I'm still bringing an analog depth gauge, watch, and cut tables as an absolute last ditch backup. Then again, I don't do buddy diving for tech until non-team bailout becomes physically unmanageable, so I'm assuming self reliance in a worst-case scenario.

I would have the same setup if I did the dives you guys do. My limit is around the 2hr deco mark, not 4-8, I only dive OC.