To Nitrox or not to nitrox ,Why and how ?

[D_B]

A point that was made earlier that nitrox is safer than air due to lower nitrogen levels forming in your tissues , I would like to clarify ... Nitrox is no safer than air and in fact is no different than air, if both are dived to their NDL's

The idea made to compare repetitive dives in one day done by two divers, one on air, one on nitrox, and see the affects on allowable bottom times between them, will readily show the difference

 

[DazedAndConfuzed]

Isnt placebo great... There have been studies on this and no link what-so-ever found. There is also no scientific reason as to why you would feel less fatigued either.

I wish I felt the placebo effect on my last trip. 5 dives a day, all I felt like was sleeping during the SI. And at the end of the week, I felt denser than a doorknob.

 

[k ellis]

On Nitrox I dont personally feel as tired as I do when I am on air. I guess I could take some placebo with it to chalk it up to the placebo but hey when something works it works.

Also as far as scientific studies they are not always what they are cracked up to be. I recall in the 1980s we were told not to eat eggs because they were nothing but high cholesterol. Then another scientific study came out saying how benieficial they are. Science works in a lot of things but then there are certain things science just cant figure out.

Just an example they did a scientific experiement a couple years ago (Which they do every year) and predicted the worst hurricane season in history yet it turned out to be the quietest in history. In short if you want something to be placebo it can be placebo but if it works for you then hey it works for you!

 

[k ellis]

I wish I felt the placebo effect on my last trip. 5 dives a day, all I felt like was sleeping during the SI. And at the end of the week, I felt denser than a doorknob.

Despite the fact people do all kinds of crazy things to give more endurance and stamina the human body can only endure so much. With 5 dives a day you will be exhausted simply because of the sheer amount of work and effort you putting forth which also includes nitrogen loading.

I do also agree with another poster above that Nitrox will give you an edge on shorter surface intervals but the studies to back this were mostly done while in comparison to air. Of course when you got a 60 minute no deco time with a percentage of nitrox but only dive to the 30 minutes of pure air you wont be as tired. Youve only absorbed half as much nitrogen versus what a diver on air would.

 

[elan]

One thing helped me a lot in eliminating the post dive fatigue was doing long ascends from 20 ft besides doing deep stops. So we would come up from 20 to 10 ft within 5 mins and then come to the surface from 10 ft within 10 mins or so. Thanks to the dive charters they are in many cases OK with that. Sometimes we have to reduce it but we never come up faster than 6-8 mins from 20 ft. When we do deep shore dives we stay at 10 ft for 10 - 15 mins. That literally eliminates the fatigue post dive on both nitrox and air.

 

[D_B]

/\ I've seen this mentioned many times and I would say that if your tired after one or two dives, you may want to slow down your ascents and see if that is why

 

[FlyingPig]

I always look for diveshops with free nitrox (or at least available nitrox with reasonable price).
Less tired = more dives = more enjoyable vacation
Usually you don't get to choose the % o2 in your tank, so as a part of planning, I don't plan to use nitrox if I'm going below 100 feet. And I don't dive walls with nitrox.
Other than that, the more the merrier.

 

[sled600]

I dive Nitox every dive.....unfortunatley, I use the cheap 28% blend.......

 

[daniel1948]

I have several comments in reply to the points raised in this thread:

When I dove air in Cozumel we made a "deep" dive to 85 feet, and then after a surface interval, we made a shallower dive to 50 or 60 feet. I routinely ran out of NDL time before I ran out of gas on the second dive. After I began using nitrox, this does not happen. On a recent trip, nitrox was not available, and again, on the second dive of the day I often ran out of NDL time before I ran out of gas. This makes nitrox very appealing to me and I now use it whenever it's available. Typically there's an added $10 per tank fee where I've dived, and that's small compared to the cost of the trip.

I do not notice a difference in fatigue between air and nitrox. But I've never tried to measure my fatigue quantitatively.

I have been on trips where the DM required everybody to surface when the first diver ran out of gas, and others where each buddy team was allowed to stay down as long as both had sufficient air and NDL time.

I spoke with a DM who said he always uses air because he wants to have to ability to go deeper in case a group member goes too deep and he has to go down after them. Obviously, this only applies for someone who might be called upon to go deeper than planned. I am not a DM, so I do not exceed my planned depth. And diving deeper than 80 or 90 feet does not interest me.

Finally, I'd like to present an argument against diving nitrox using air tables: If you absolutely adhere to the tables (or computer) there's no problem. But it would be easy for the diver in this case to feel he can exceed the NDL because after all, he's breathing nitrox and has the added margin. Once he does this, he is moving into a scenario where he does not know his actual NDL. I'd argue for setting your computer (or choosing your table) according to the actual gas you are breathing, and getting your added margin of safety by staying well within the prescribed limits. You could decide to ascend when your NDL time reaches ten minutes, or whatever, rather than waiting until it's down to one minute. This strategy will give you the same margin of safety you presumably get by diving air tables on nitrox, but with the difference that you know at all times what your actual NDL time is, rather than using air limits and then never knowing how much margin you really have.

 

[doctormike]

Finally, I'd like to present an argument against diving nitrox using air tables: If you absolutely adhere to the tables (or computer) there's no problem. But it would be easy for the diver in this case to feel he can exceed the NDL because after all, he's breathing nitrox and has the added margin. Once he does this, he is moving into a scenario where he does not know his actual NDL. I'd argue for setting your computer (or choosing your table) according to the actual gas you are breathing, and getting your added margin of safety by staying well within the prescribed limits. You could decide to ascend when your NDL time reaches ten minutes, or whatever, rather than waiting until it's down to one minute. This strategy will give you the same margin of safety you presumably get by diving air tables on nitrox, but with the difference that you know at all times what your actual NDL time is, rather than using air limits and then never knowing how much margin you really have.

I suppose, sort of like setting your watch ahead 10 minutes so you won't be late, but then allowing yourself an extra ten minutes to get places because you know that your watch is 10 minutes fast...?

I don't think that's an argument against diving nitrox using air tables - that's an argument against diving nitrox while pretending to use air tables...