Why do you use nitrox ?

[muddiver]

I'm just curious if you're saying you get less narced because someone told you that EAN is less narcotic (placebo effect) or whether you really feel a difference.

It's highly debatable whether O2 is less narcotic than N2.
You'll find various threads here on SB.

There aren't really any exact values or numbers to determine the ratio of oxygen's narcotic effects, but several sources claim it to be about as narcotic as nitrogen, ie.: The Physiology and Medicine of Diving" by Peter Bennett and David Elliott, 4th edition, 1993, W.B.Saunders Company Ltd, London.

Richard Pyle says that the relation of the narcocity value of oxygen vs. nitrogen depends on their fraction in current gas mix.

I am going to disagree with you because the narcotic affect of oxygen does not factor in shallower than about 300 feet sea water. Otherwise all the trimix trained divers would have wasted all that money on learning to and using helium to reduce/remove the narcotic effects from breathing nitrogen at depth. Anyway, who dives deep enough, regularly to get narced on oxygen?

 

[MXGratefulDiver]

Cool stickers.

 

[TSandM]

Like Bob, I dive 32% all the time, because I pay a flat fee for a year's Nitrox. It allows me to do profiles like the one he put up (which is pretty typical around here). And I have memorized the tables for 32%, which makes tracking my deco status easy. For the amount of diving I do, there's really no downside . . . I don't push the MOD because my personal hard deck is 100 fsw without helium, and cumulative O2 toxicity on recreational dives requires more diving than I'm willing to do in a day

I also use Nitrox to accelerate deco.

 

[Rick Murchison]

I am going to disagree with you because the narcotic affect of oxygen does not factor in shallower than about 300 feet sea water. Otherwise all the trimix trained divers would have wasted all that money on learning to and using helium to reduce/remove the narcotic effects from breathing nitrogen at depth. Anyway, who dives deep enough, regularly to get narced on oxygen?

No, most trimix divers (at least the ones I dive with) figure their END based on N₂+O₂ (well, actually, for simplicity, most just do 100% - He%). That is, they give full narcotic weight to the oxygen content of the mix, rather than just N₂/.79.
For example... let's compare three mixes, at a depth acceptable for them all, 30 msw...
1. Air
2. NOAA Nitrox 1 (EAN32)
3. Trimix 16/50

Now, using the Nitrogen only method of calculation...
for Air, we have .79*4 ATA/.79 = 4 ATA, or 30m END
for EAN32, we have .68*4 ATA/.79 = 3.4 ATA, or 24m END
for Trimix 16/50, we have .34*4/.79 = 1.7 ATA or 7m END

Using the N₂+O₂ method, we have
for Air, (.79+.21)*4 ATA = 4 ATA, or 30m END
for EAN32, (.68+.32)*4 ATA = 4 ATA, or 30m END
for Trimix 16/50, we have (.34+.16)*4 ATA = 2 ATA, or 10m END

It is my experience that I feel precisely zero difference in narcosis when switching from air to Nitrox, and so I find the N₂+O₂ method more practical and accurate for me when making decisions on the END portion of gas planning. (also makes mix planning easier... if I establish a desired END of 4 ATA (100 FSW or 30 msw), for example, then I take the planned depth in ATA, say 7 ATA (200 FSW or 60 msw), and just put 3 parts He (corrected for real gas laws, of course) and 4 parts EAN32 in the bottles & I automatically have a 100' END and 1.28 PO₂ on the bottom.... and the math was pretty easy, eh?)
--
The bottom line? I am in full agreement with SSI's advice on planning Nitrox dives w/r/t narcosis, "It is best not to assume any reduced narcosis from the use of Nitrox."
--
Now, back to the original question...
I use Nitrox because I can get a lot more time looking at the wonderful world underwater when compared to air. Indeed, if I divide the total cost of a trip by the minutes underwater I can readily see that the overall dollars-per-minute underwater is far less when I use Nitrox to its full extent over air on nearly any "normal" recreational dive trip.
Rick

 

[deepstops]

I am going to disagree with you because the narcotic affect of oxygen does not factor in shallower than about 300 feet sea water. Otherwise all the trimix trained divers would have wasted all that money on learning to and using helium to reduce/remove the narcotic effects from breathing nitrogen at depth. Anyway, who dives deep enough, regularly to get narced on oxygen?

Do you have references that provide a basis for these statements??

 

[bamamedic]

I use Nitrox to reduce the amount of deco obligation I wind up with...air is cheap, but even a lean Nitrox mix appropriate for the MOD and depth really does a lot to reduce the time I've got to spend on deco. 130 feet for 30 min on air gives me a 20 foot stop of 33 min, but it's only 20 min on EAN28.

And of course, for accelerated deco, I use an assortment of EAN50, EAN80, and 100%...whatever's appropriate for the mission at hand (and whatever I happen to have handy at the time!)

 

[Rick Murchison]

Don't forget this one

Rick

 

[Ber Rabbit]

I use nitrox on dives I want to remember in detail especially anything deeper than 60 feet. Dove the Arabia at Tobermory on air (104 to the bottom but most time spent in 80 foot range) and couldn't recall the third anchor even though my husband said he pointed it out and I acknowledged. Was at 50 feet on the ascent line trying to rewind my finger spool and could not accomplish the task, husband took it away from me and wound it up fearing I would run myself out of air messing with it. Did the same dive on nitrox a year later and every aspect of the dive was crystal clear and I'm still able to recall it.

Learned not to dive nitrox in the local quarry. I have a great time on air in the 30-50 foot range, I've always enjoyed quarry diving and never understood why people said it was boring. That was until I did the dive on 36%, wow what a difference for me! I suddenly realized that yes, this really IS boring. I don't do nitrox in the shallows any more. I'm attentive to my air supply, my buddy and our plan on either gas it's just the scenery that numbs out on air.
Ber :lilbunny:

 

[Blackwood]

I am going to disagree with you because the narcotic affect of oxygen does not factor in shallower than about 300 feet sea water. Otherwise all the trimix trained divers would have wasted all that money on learning to and using helium to reduce/remove the narcotic effects from breathing nitrogen at depth.

Say what?

A gas isn't either narcotic or non-narcotic. The less narcotic gas in the mix, the less narcotic that mix (all else being equal).

The body requires oxygen at a certain pressure to function. You can only get rid of some of it. The body doesn't require nitrogen at any pressure to function. You can (if you want) get rid of all of it.

 

[Dr Wu]

I use nitrox on dives I want to remember in detail especially anything deeper than 60 feet. Dove the Arabia at Tobermory on air (104 to the bottom but most time spent in 80 foot range) and couldn't recall the third anchor even though my husband said he pointed it out and I acknowledged. Was at 50 feet on the ascent line trying to rewind my finger spool and could not accomplish the task, husband took it away from me and wound it up fearing I would run myself out of air messing with it. Did the same dive on nitrox a year later and every aspect of the dive was crystal clear and I'm still able to recall it.

Learned not to dive nitrox in the local quarry. I have a great time on air in the 30-50 foot range, I've always enjoyed quarry diving and never understood why people said it was boring. That was until I did the dive on 36%, wow what a difference for me! I suddenly realized that yes, this really IS boring. I don't do nitrox in the shallows any more. I'm attentive to my air supply, my buddy and our plan on either gas it's just the scenery that numbs out on air.
Ber :lilbunny:

You feel Nitrox reduces narcosis?

Or at least lessens memory loss and coordination problems?

Why do you feel this way? What do you base this on?