Hypothetical Pony Bottle Ooa Situation

[TMHeimer]

Agree with all on not bothering with changing the computer. Protocol is to ascend at a safe speed (air permitting of course), then do the safety stop, preferably longer than normal, even to last as long as your air lasts. Re-setting the computer during the dive doesn't change any of that.

 

[Tug]

I'd just ascend without changing my computer over and not worry about it. If I had time on my safety stop then I might change it over, but like most of the other people said, it's not going to change much.

 

[Patoux01]

Just end the dive "normally", maybe extend the safety stop a bit, or the surface interval, or both. Wouldn't really matter imo... If you're one of those guys that keeps at 1' NDL, then you deserve what's coming at you imo.

 

[Oldbear]

Why fill the pony bottle with air? Why not fill it with EAN 28? This way you never have to worry about you MOD at any recreational limits and you don't have to even consider switching gases on you pdc. What is the cost difference between air and .28 O2 at you fill station?

 

[Patoux01]

That doesn't solve the problem actually... If he's diving 32 one time, he's gonna have to purge the pony?

 

[Oldbear]

He already said he was using EAN 28. Even if he is using EAN 32, 28 is still closer than 21.

I ask again, if you are diving on Nitrox why use air in your pony?

 

[Patoux01]

I might have misunderstood, but to me the 28 was just an example... Could have been 29, 30,31,32, 23, whatever.

So you're happy switching from 32 to 28, but 28 to 21 is a no-no. Where do you draw the line?

Take air in the pony and you're free of MOD. Take a nitrox and you're not.

 

[g2]

I agree that the best action is not to worry about it, just ascend.

That said, I also dive to 130fsw occasionally and carry EAN 32 in my pony (MOD 132fsw @ 1.6 ppO2). So long as you're diving conservatively, a brief exposure to a 1.6 ppO2 is unlikely to cause a problem, and it can only accelerate off-gassing at the safety stop. No computer fuzting required.

 

[Reku]

Hmm well ... In this situation I would probably switch over to the pony and then while ascending change the gases on my petrels, I wouldn't have anything else interesting to do until like 80ft or so where I launch my dsmb. This is quite a personal question because divers ability to task load is different. If you can do it while narked out of your skull - do it, if you can't - then don't. It is what it is. Practice makes perfect.

Like others have said - having air in your pony makes it so you are not depth limited and have to refill your pony for deeper mixes every dive. It's a safety measure anyway ... put air in it and use it to get to the surface - none of this gas matching between backgas and pony really matters in this context.

 

[Doby45]

I am with @Reku, very simple change on the ole Petrel.