Whither Nitrox?

[RickSp]

I just got back from a wonderful trip to Bonaire. The dive shop that we were using, Bonaire Dive and Adventure, offered Nitrox (certification as well as tanks). Being relative novices we happily used compressed air.

I am trying to understand the practical benefits of Nitrox. I understand that it gives you longer potential bottom time, or inversely a greater margin of safety. That's great. What doesn't necessarily make sense to me is what this means in practice. One source I read quotes a no-decompression time with compressed air of 80 minutes at 50' and 200 minutes with Nitrox at the same depth. Of course, with a standard 80 cu ft aluminum tank I will probably use my available air in about 50-60 minutes depending on water temperature, so while I would be absorbing a lot less nitrogen with Nitrox, my bottom time would be limited not by no decompression time limits but by my tank size.

I have heard and read that Nitrox is less fatiguing than diving with compressed air and that it can also keep you warmer. This may be the case but speaking with one diver we met on the trip, ( a highly unscientific survey) he commented that he didn't notice a difference when breathing Nitrox as compaired to compressed air. I also noted a fellow diver breathing Nitrox who always seemed to come up shivering, though she was wearing a full wet suit while I was wearing a shortie. (Significant only because I have a reputation as a real cold water wimp.)

I will admit to feeling exhausted at the end of each day after two dives, but them I also felt exahusted after a day's snorkeling with my eight year old.

So, is Nitrox the air of the future or a passing fad? Any opinions?

Rick

 

[pennypue]

Rick, I love it personally.
For you, if you're not hitting the NDL then you are missing the benefit of extended bottom times. But I wouldn't say it would be worthless for you. Less nitrogen loading during your 50-60 minute dive will mean a shorter surface interval required since you'll end your dive in a lower pressure group and not need as much time to off gas. (I've been studying myself )

But you said you feel whupped? Take it, try it. I don't feel as whupped after two dives. Did four in one day March 19th and I was one tired puppy. Wished I had nitrox then. I do find that I'm much less tired diving nitrox. I'm ending my day in a lower pressure group, so there's less nitrogen loaded up in my tissues.

I try to keep my tissues happy.

If you're still not sure, get the book and read it. Then decide if you want the course. But I think you will.

 

[OE2X]

I can't say that I notice any difference in warmth with nitrox vs. air. You start getting into the warmth factor when you go to breathing trimix. Then you use argon for your drysuit.

Extended bottom times particularly in the 100' area are really nice. If you dive with larger high pressure tanks it is very easy to go into deco. Having an extra 30% of bottom time is nice advantage (air = 20 min vs. 32% nitrox = 30 min @ 100')

Penny is correct as far as the nitrogen loading is concerned. It shortens your SI time if you choose to. I find that my fatigue is lessened while diving nitrox. Another way to help you lessen your nitrogen loading with both air and nitrox is to spend more time at 30' or shallower than you did at your deepest point.

Now to my rant. I have dove air for many years. A few years ago I switched to about a third of my dives being nitrox and the rest air. This year with 70 dives and counting I have dove exclusively 32%. I can easily do three dives in a day and feel a normal fatigue level. I can stay in NDL with no worries. I am convinced that for the kind of diving that I do that the safety window has been increased. In effect I have lessened the risk of getting bent.
I have a friend that is about to get his OW cert. He called and asked if for an additional $75. he should get nitrox certified. I told him absolutely. The ability of having longer NDL's and lower nitrogen loading is worth every penny.

 

[Damselfish]

I just got back from a wonderful trip to Bonaire. The dive shop that we were using, Bonaire Dive and Adventure offered Nitrox (certification as well as tanks). Being relative novices we happily used compressed air.

I am trying to understand the practical benefits of Nitrox. I understand that it gives you longer potential bottom time, or inversely a greater margin of safety. That's great. What doesn't necessarily make sense to me is what this means in practice. One source I read quotes a no-decompression time with compressed air of 80 minutes at 50' and 200 minutes with Nitrox at the same depth. Of course, with a standard 80 cu ft aluminum tank I will probably use my available air in about 50-60 minutes depending on water temperature, so while I would be absorbing a lot less nitrogen with Nitrox, my bottom time would be limited not by no decompression time limits but by my tank size.

You can get more bottom time, less nitrogen, or a combination of both. All are good things. Whether bottom time is limited by tank size rather than NDL depends on the person and the profiles. Air is fine, but it is worth getting Nitrox certified sometime as you may find it would really benefit you as you dive more.

I have heard and read that Nitrox is less fatiguing than diving with compressed air and that it can also keep you warmer. This may be the case but speaking with one diver we met on the trip, ( a highly unscientific survey) he commented that he didn't notice a difference when breathing Nitrox. I also noted a fellow diver breathing Nitrox who always seemed to come up shivering, though she was wearing a full wet suit while I was wearing a shortie. (Significant only because I have a reputation as a real cold water wimp.)

Many people feel they're less tired, some don't. I don't think I've heard that it keeps you warmer. In any event, there are many factors that affect both of these things. For example, someone who moves around in the water a lot will tend to keep warmer than someone who isn't. I think people from cold climates will be warmer than people from warm climates. And some people are just better insulated.

I will admit to feeling exhausted at the end of each day after two dives, but them I also felt exhausted after a day's snorkeling with my eight year old. Being tired after an active day of vacation is not necessarily a bad thing.

No, but it's nice to stay awake for dinner or a night dive.

So, is Nitrox the air of the future or a passing fad? Any opinions?

I wouldn't call it the air of the future, it's been around awhile, pretty common now and getting more common, not a passing fad. PADI started doing certs in 95 but it was around well before that. If you go on a liveaboard that has it, in my experience nearly everyone will be using it. People are often doing many dives say 4-5/day where it's going to make a much bigger difference than for 2/day.

 

[RickSp]

Sorry for apparently posting this twice. Not sure how I managed that.

I have no doubt that Nitrox makes a huge difference for commercial divers but remain a bit sceptical of its utility for recreational use. I'm sure I'll get Nitrox certified the next time I am near warm clear water and give it a try. With an 80 cu ft 3000 psi tank I'm not use it will make much difference, but who knows.

The level of fatigue I feel after two dives even with compressed air doesn't seem excessive. I almost associate fatigue with outdoor and active vacations. If I'm not at least a bit worn out by dinner time, I obviously didn't do enough in the daylight.

Rick

 

[Doc Intrepid]

As noted, if you're basically breathing your tank down before reaching your NDLs anyway, and only doing two dives a day, the benefits of EAN may be negligible.

OTOH, if you're doing more aggressive repetitive diving, say 3-5 dives per day to depths between 60' and say 90'-100' or so, this is where having less nitrogen in your gas may be beneficial (for both extended bottom times as well as safety).

Residual nitrogen impacts your NDLs, and in aggressive diving, multi-day liveaboard circumstances (for example), EAN may be a safer option. As always, YMMV.

 

[JaxvilleDiver]

I have no doubt that Nitrox makes a huge difference for commercial divers but remain a bit sceptical of its utility for recreational use.

I have been a commercial diver for many years now and in all of that time I have never used NITROX or even come across a company that does. After speaking with several friends of mine that are also commercial divers, none of them have used NITROX on the job either. It's mainly used as a recreational mix. The only mixed gas that I have used working is HELIOX.

Recreationally, it does have some advantages, as well as disadvantages.

Personally (aside from when I am working with students) I prefer to dive air.

 

[RickSp]

I have been a commercial diver for many years now and in all of that time I have never used NITROX or even come across a company that does. After speaking with several friends of mine that are also commercial divers, none of them have used NITROX on the job either. It's mainly used as a recreational mix. The only mixed gas that I have used working is HELIOX.

Recreationally, it does have some advantages, as well as disadvantages.

Personally (aside from when I am working with students) I prefer to dive air.

Interesting. I had read that Nitrox was popular with commericial divers. Just shows one shouldn't believe everything one reads on the net.

Thanks for the response.

Rick

 

[Don Burke]

I am trying to understand the practical benefits of Nitrox. I understand that it gives you longer potential bottom time, or inversely a greater margin of safety. That's great. What doesn't necessarily make sense to me is what this means in practice. One source I read quotes a no-decompression time with compressed air of 80 minutes at 50' and 200 minutes with Nitrox at the same depth. Of course, with a standard 80 cu ft aluminum tank I will probably use my available air in about 50-60 minutes depending on water temperature, so while I would be absorbing a lot less nitrogen with Nitrox, my bottom time would be limited not by no decompression time limits but by my tank size.

The benefits generally kick in at about fifty feet if you are making two dives a day and a bit shallower if you are making more.

Around here, Nitrox tanks are usually larger than 80, with 125 steel being pretty common. I have a couple of 112s I use for singles diving with Nitrox.

I have heard and read that Nitrox is less fatiguing than diving with compressed air and that it can also keep you warmer.

I can verify less fatigue and I have attributed it to low grade DCS. Some call this "subclinical DCS", which I think may be incorrect since (in my layperson understanding) subclinical means no symptoms and fatigue would indeed count as a symptom.

I have never heard anything about being warmer than air.

This may be the case but speaking with one diver we met on the trip, ( a highly unscientific survey) he commented that he didn't notice a difference when breathing Nitrox as compaired to compressed air. I also noted a fellow diver breathing Nitrox who always seemed to come up shivering, though she was wearing a full wet suit while I was wearing a shortie. (Significant only because I have a reputation as a real cold water wimp.)

I will admit to feeling exhausted at the end of each day after two dives, but them I also felt exahusted after a day's snorkeling with my eight year old.

If you are tired, you are tired.

So, is Nitrox the air of the future or a passing fad? Any opinions?

I would call it one of the many gasses of today.

 

[RickSp]

The benefits generally kick in at about fifty feet if you are making two dives a day and a bit shallower if you are making more.

Around here, Nitrox tanks are usually larger than 80, with 125 steel being pretty common. I have a couple of 112s I use for singles diving with Nitrox.I can verify less fatigue and I have attributed it to low grade DCS. Some call this "subclinical DSC", which I think may be incorrect since (in my layperson understanding) subclinical means no symptoms and fatigue would indeed count as a symptom.

I have never heard anything about being warmer than air.If you are tired, you are tired.I would call it one of the many gasses of today.

I think the environment I was diving in worked against the possible benefits of Nitrox. The boat dives always had a mix of compressed air and Nitrox divers so the dive master had to tailor the depths to the compressed air types.

The dives were typically planned so that the first half of the dive was on the reef wall at somewhere in the 40 - 70 foot range while the second half was closer to 20 feet along the reef edge. The afternoon dive was also shallower than the morning dive. We were never particularly close to our no-decompression limits so I suspect that fatigue from low grade DCS wasn't a factor.

Thank you and everyone for their comments. Interesting stuff.

Rick