Nitrox as air? Anyone do this?

[wildbill9]

I am getting ready for our first (but not last) trip to Bonaire . The most dives I usually do is three a day and we expect to far exceed this on our trip. After reading some of the articles in the latest DAN publication specifically about skin bends we were talking about leaving our computers set to regular air instead of the Nitrox we will be using. We will not exceed 100 ft. but just wanted to be ultra safe.

Is this a good or a bad idea?

Thanks for your help!

Bill

 

[Doppler]

Do it on sport dives all the time... just watch your depth is well above the maximum operational depth of your mix.

 

[MB NZ]

Personally, I don't think it is a bad idea and do it on occasion. It would be prudent to still analyse your fills and keep an MOD in mind.

 

[victorzamora]

I don't do that, and here's why: I like to know where I'm actually at, per the computer's algorithm. I leave it on the nitrox setting I'm actually diving, and just plan on leaving the bottom before the NDLs hit zero, padding my SIs, and adding time to safety stops. Instead of letting the computer be wrong and me not know what my theoretical status is, I let my computer be right (in case I DO want to push my NDLs that dive, or my MOD, or whatever)....and I had conservatism purposefully. Somewhere like Bonaire you can probably (I'm guessing as I've never been there) add tons of conservatism by swimming back towards shore and burning the last 300psi in your tank off at 20ft. It's how all of the safety stops in Roatan are done. They're "safety stops" in that you happen to be at 15 or 20ft....while in reality you're still just having a great reef dive.

So, no...it's not a bad idea. Plenty of people do it, and there's nothing wrong with doing it. I, however, like to keep track of my own conservatism.

 

[BRT]

Why not just dive it as nitrox and not push your NDL's? Just because your computer says you have more bottom time doesn't mean you have to use it. I like my long NDL available with nitrox and a liberal computer but I seldom push those limits.


Victor Zamora just beat me to it.

 

[rhwestfall]

can you set a conservatism factor, diving the computer set to the proper mix?

 

[boat sju]

Or you can do what I do and carry a backup air computer in my bc pocket. It's interesting to see the difference between the two computers. (Especially the ascent rate indicator.)

Three hour-long dives a day and never really had any NDL issues on the air computer that I could tell. We don't usually spend much time very deep though.

 

[tursiops]

It's interesting to see the difference between the two computers. (Especially the ascent rate indicator.)

How is this affected by what gas the computers are set for?


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[dumpsterDiver]

I think it makes more sense to punch in your nitrox mix and then decide you will leave the bottom with 5 or 8 min of no-deco time left. This gives you a better metric of how close you are coming to the No-deco limit than simply diving air to the limit.

However, one reason to put a computer into the air mode, is to actually learn what your computer does when it goes into deco.. This can be a valuable lesson, if/when you screw up some time in the future and accidentally "overstay your welcome" i.e., go a little into deco. Some people tend to freak out if they put a computer into deco and they have a tendency to become very nervous AND try to rush their ascent and begin their deco stops ASAP (which incidentally, is not the best way to handle it).

If you do want to experiment a little, stick with your dive buddy close and have one person using a nitrox computer and the other with the computer on air - they would both be using the same nitrox mix. ,,. let the air computer go into deco for a minute or two (while you know you still have lots of actual no-deco time based on the other nitrox computer) and then both divers practice a simulated deco ascent. Obviously you need enough gas to make the ascent.

If that sounds stupid or dangerous, then just punch in the mix on your computer and leave the bottom X minutes early.

 

[HungoverDiver]

How is this affected by what gas the computers are set for?


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I think that might be their point. It doesn't matter.


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