85m air dive

[laurin]

Kern already covered it

It would still be interesting to hear your take on why subjecting yourself to a ppO2 of nearly 2.0 at 85m is reasonable, considering you then cut the bottom time next to nothing because you suddenly are aware of the possibility of CNS tox...

//LN

 

[Cave Diver]

Kern already covered it

So, doesn't that seem like a good argument for using a different gas at depth to lower the O2 percentage?

Adding just 4 minutes to bottom time (say in the event of a problem) increased the deco to almost 1.5 the times. That additional bottom exposure jumps the CNS% up considerably as well.

Dropping the O2 content of the bottom mix substantially cuts the CNS%. If CNS is such a concern that you don't want to spend additional time on 100% near the surface, why not just fix the problem at the source?

I'm still interested in your thoughts on the points I brought up as well.

 

[Blackwood]

It would still be interesting to hear your take on why subjecting yourself to a ppO2 of nearly 2.0 at 85m is reasonable, considering you then cut the bottom time next to nothing because you suddenly are aware of the possibility of CNS tox...

//LN

I agree. It seems like an odd contradiction to avoid high PO2 when it is favorable in exchange for exposing yourself to high PO2 when it isn't.

After having taken a narcosis mgmt course, it seems that maybe hypoxic nitrox would be a better choice than air (exchanging deep PO2 for some additional shallower PO2).

 

[berk]

I agree. It seems like an odd contradiction to avoid high PO2 when it is favorable in exchange for exposing yourself to high PO2 when it isn't.
PO2).

And it's weak sauce. Real air divers deco on air too.

 

[Kern]

Kern already covered it

Wait just a minute here. You can't say things like that. You're gonna ruin my rep as one of the worlds biggest sarcastic cynics. I must be getting too subtle in my decrepitude. :shocked2:

 

[Tortuga68]

It would still be interesting to hear your take on why subjecting yourself to a ppO2 of nearly 2.0 at 85m is reasonable...

I agree... it seems that maybe hypoxic nitrox would be a better choice than air (exchanging deep PO2 for some additional shallower PO2)

I could use a suite of gasses to do so & keep my CNS below 50%

So, doesn't that seem like a good argument for using a different gas at depth to lower the O2 percentage?

If the thread was titled "I'm planning an 85m dive, what gas should I use?" then I'd be very interested in discussing these points. But it was planned as a deep air dive (or rather series of dives)

I'm not saying your points aren't worthy of discussion, or that you shouldn't discuss them, just that I don't see them as relevant in this instance. It's not like I sat down and said hmm, I think I'll choose to use air instead of any other gas for this dive because I think it's the best option

You don't always need "the best", sometimes adequate will suffice

 

[Cave Diver]

If the thread was titled "I'm planning an 85m dive, what gas should I use?" then I'd be very interested in discussing these points. But it was planned as a deep air dive (or rather series of dives)

I'm not saying your points aren't worthy of discussion, or that you shouldn't discuss them, just that I don't see them as relevant in this instance. It's not like I sat down and said hmm, I think I'll choose to use air instead of any other gas for this dive because I think it's the best option

You don't always need "the best", sometimes adequate will suffice

Silly me. I figured since you posted this in the Advanced Scuba Discussions instead of posting it as a trip report in the local sub forum that a discussion would be part of it.

What is your definition of adequate? Or is that another thing that's not up for discussion?

 

[Tortuga68]

Like I said, feel free to discuss anything you like

 

[berk]

Exactly. If you want to simply make an announcement then close the thread or post in the trip report area.

Take out the depth and bottom mix, and the way things appear are just so unusual that we are asking questions. Your tone is also a little odd as to be "troll like" thus some of our remarks.

I believe the foolish aspects of air diving are accepted, widely known and documented, and have been beaten to death. Still.....

Perhaps there is someone who is going to an area without helium for a special dive or task. They might be looking for a place to practice or experience deep air in a more controlled, tropical, and resort type area before they go. Your post could be of some value.

 

[berk]

You don't always need "the best", sometimes adequate will suffice

Certainly, but it seemed that you had access to oxygen and a compressor. From there you can get all kinds of mixes with a whip and a gauge.