Diving 32% Nitrox with "Air" Algorithms

[MaxBottomtime]

After reading the entire thread I have come to the conclusion that most divers want complicated solutions to a simple problem. If I had been bent or suspected I was susceptible to DCS, I would simply not push my NDL. I wouldn't change the settings in my computer to give a perceived cushion.

 

[tursiops]

After reading the entire thread I have come to the conclusion that most divers want complicated solutions to a simple problem. If I had been bent or suspected I was susceptible to DCS, I would simply not push my NDL. I wouldn't change the settings in my computer to give a perceived cushion.

Good approach, but it requires attention to your computer and some self-discipline. Might not be very useful to everyone. The worst is, "I'm not going to let some silly computer that has never been fully verified and is just a guess anyway to tell ME what to do!"

 

[MaxBottomtime]

One of the best quotes I've heard is there are two things that kill divers, greed, and arrogance. If someone believes they are smarter than their computer, tables, and decades of research, let them dive any way they choose. They have no one to blame but themselves when things go south.

 

[scubadada]

One of the best quotes I've heard is there are two things that kill divers, greed, and arrogance. If someone believes they are smarter than their computer, tables, and decades of research, let them dive any way they choose. They have no one to blame but themselves when things go south.

I would say that there are three things, greed, arrogance and ignorance. I would add a fourth, but one of my fellow moderators would probably delete my post, you could easily guess.

 

[MaxBottomtime]

No matter how ignorant they may be, every certified diver should have knowledge of NDL.

 

[Cheizz]

Apparently yes! Even with the best intentions of begining to surface with at least 10 minutes of NDL, it's real easy to see something really cool and get distracted and ascend with only 5 minutes remaining.

So, if they don't listen to their computer/planning anyway, then why bother using other settings or manipulating the dive computer's output?

Apparently, distractions are more powerful than consciously following even a simple dive plan. A scary thought....

 

[arew+4]

So, if they don't listen to their computer/planning anyway, then why bother using other settings or manipulating the dive computer's output?

Apparently, distractions are more powerful than consciously following even a simple dive plan. A scary thought....

You all act as if every dive is hyper technical multi stage decompression dive that requires detailed plans and ridgid adherence where any deviation will end in certain death.

The extent of most dive plans is, if there is a current swim into it on the way out be back on the boat with 500 psi. Try not to go deeper than X.

Personally, my wife dives EAN, set to the proper percentage, but with her algo and conservatism dialed up so she's a pretty good match to me on air with clean computers. We still dive the shorter NDL. She wants the additional margin of safety I'm fine with what's worked for the last thirty years.

YMMV

Oh, and one time we had too many Nitrox tanks and not enough air tanks. I dove a Nitrox tank on air settings without a Nitrox cert and I didn't even die.

 

[Belzelbub]

So, if they don't listen to their computer/planning anyway, then why bother using other settings or manipulating the dive computer's output?

Apparently, distractions are more powerful than consciously following even a simple dive plan. A scary thought....

Agreed. And if they aren't following their plan (or plan with contingency), I'm not sure how any setting on a computer is going to help them. They apparently don't listen.

You all act as if every dive is hyper technical multi stage decompression dive that requires detailed plans and ridgid adherence where any deviation will end in certain death.

Not at all. A dive plan can be very simple. Most of the dives I do are well away from NDL, so limited primarily by gas supply. Point is a limit is a limit. If Plan A calls for heading up when NDL = 10, then that's the Plan. Perhaps a contingency is to accept NDL = 5. If so, then there are a couple minutes if that whale shark visits.

That's different than just ignoring the NDL and abandoning the plan, regardless of how simple the plan is.

My dives generally fall into two buckets. Either I'm working at the aquarium or I'm hunting. Depths at the aquarium are relatively shallow, so really no chance of exceeding NDL. My plan on those is to surface with at least 500PSI. When hunting, it will depend on the depth and previous dives, but the plan is the plan. Although, I've been tempted, I don't alter the plan because that grouper just showed up as I was at the limit. No fish is worth your life, so have a plan and stick to it. Even if it's as simple as surface with 500 psi and ascend when NDL reaches X.

 

[L13]

The extent of most dive plans is, if there is a current swim into it on the way out be back on the boat with 500 psi. Try not to go deeper than X.

You left of the part about not exceeding NDL.

Personally, my wife dives EAN, set to the proper percentage, but with her algo and conservatism dialed up so she's a pretty good match to me on air with clean computers. We still dive the shorter NDL. She wants the additional margin of safety I'm fine with what's worked for the last thirty years.

She seems wiser than you.

Oh, and one time we had too many Nitrox tanks and not enough air tanks. I dove a Nitrox tank on air settings without a Nitrox cert and I didn't even die.

Of course you didn't die. Presumably you know enough (or at least your wife knows enough) to avoid the main hazards, making the risk on any one dive low enough to get away with it. EAN diving is not hard, even though the risks are real.

But this is the Basic Scuba forum, if everyone followed your example a few people probably would die that otherwise wouldn't have.

 

[arew+4]

You left of the part about not exceeding NDL.


She seems wiser than you.


Of course you didn't die. Presumably you know enough (or at least your wife knows enough) to avoid the main hazards, making the risk on any one dive low enough to get away with it. EAN diving is not hard, even though the risks are real.

But this is the Basic Scuba forum, if everyone followed your example a few people probably would die that otherwise wouldn't have.

The bit about NDL is always implied!

Even if you went to rec limit of 130' on EAN 32, your max ppo2 would be just under 1.6 WHILE THIS IS AN UNACCEPTABLE LEVEL OF RISK, it is not guaranteed to cause O2 toxicity or cns symptoms.

This a recreational scuba site, diving is supposed to be fun. There are risks and you must decide how to mitigate them. Do what works for you, but accept the consequences. Provided you pay attention to the MOD of the Nitrox blend and you are using 32 or less you will have a very hard time raising your O2 sat to anything approaching dangerous. Therefore in my estimation and that of some medical professionals, EAN 32 on air calculations is fine, and substantially reduces your nitrogen loading.