To nitrox or not

[drbill]

Until about a month ago I would have said wait. In 44 years of diving I had never seriously considered Nitrox. However, recent diving experience suggests it could be a help to me and I am reconsidering.

In the past I've almost always done multi-level dives with decreasing depths over time. For example dive to 100 ft for 10 min, rise slowly to 50-60 ft for 20 min, rise slowly to 30-40 ft for 20 min, and then 15-20 ft for the remainder of the dive. Obviously this allowed for off-gassing as the dive progressed.

Over the past month I've been diving off boats exclusively and do a lot more "square profile" dives (down to depth for appropriate bottom time, then slow ascent with safety stop). Due to the nature of my work (filming) I've often remained at the depth until nearly reaching deco (or going into it on occasion).

Under my previous scenario I've been able to do 4-6 dives each dive day without getting tired afterwards. Under the new scenario I'm finding that three long dives (50-70 min each) leave me tired. Several times I've fallen asleep at the computer while editing.

Under the second scenario I think that Nitrox would be a big benefit.

Your diving patterns may differ from mine so this is my suggestion based on my experience. Your mileage may vary, but it doesn't hurt to be Nitrox certified.

Dr. Bill

 

[ShakaZulu]

When we dive, our bodies absorb additional inert gases, mostly nitrogen. We realize that eliminating the nitrogen is important so as not to form large bubbles in our blood and tissues that results in decompression sickness (DCS). Models have been made for tables and dive computers to allow us to safely ascend from dives without developing DCS. Recreational dive training uses these tables and dive computers to limit depth and bottom time so that decompression stops are not required. Even so, we must be aware that since off-gassing occurs with every dive, then every dive is a decompression dive. The reason all dives are decompression dives is simple - the diver is ascending from under pressure (i.e. decompressing). I think there is long term benefits diving enriched air with regard to micro bubbling, that we don't know about yet.

 

[oceancrest67]

I have a chance to take a Nitrox class locally. I am an inexperienced diver (around 20 dives). Should I wait to get more dives under my belt before I pursue Nitrox?

I say go for it. I was diving for about ten years before I took it...being aware of nitrox and oxygen toxicity as well as max operating depths can enhance your next leap into advanced nitrox and extended range diving if you are inclined.

 

[BarryNL]

Not to mention that you "feel better" after the dives.

Erm... Actually I only been able to find details of one study into this and the conclusion was that there was no noticable improvement in how people felt after the dive (well, it was actually done in a compression chamber).

On current evidence this is more marketing than fact.

 

[jonnythan]

Erm... Actually I only been able to find details of one study into this and the conclusion was that there was no noticable improvement in how people felt after the dive (well, it was actually done in a compression chamber).

On current evidence this is more marketing than fact.

Doing the same dive with air vs 32, I know I feel better afterward when on 32..

 

[The Kraken]

Barry,
The effects of increased oxygen content of breathing gasses is a very subjective physisological matter and is totally dependent upon the individual.

Personally, given two identical dive profiles, I can feel a significant difference in my energy level when diving nitrox and regular (21% O2) air.

No, I have no emperical data to support my hypothesis, but I know how I feel. You don't have to have data to support the fact that you have the flu, do you?

the K

 

[DORSETBOY]

change my view on nitrox almost as often as I change my pants! I'm starting to come down very much on the viewpoint that it is beneficial and that I am happy to accept the minimal additional cost (once having O2 clean equipment).

 

[GrierHPharmD]

I, too, feel subjectively better using an enriched mix. I'd advise taking the course, if only because it will help you broaden you knowledge of gas physics and physiology (at least it did for me.)

I found the course to be pretty easy and have found that diving nitrox leaves me feeling more energetic after a long day of diving. I think that too many people get nitrox confused with technical diving, which is a whole different order of magnitude in complexity. Diving within recreational limits under nitrox is pretty straightforward.

Hope that helps,
Grier

 

[JimC]

On Nitrox:
I don't feel less narced.
I don't feel less tired.
I don't see much bottom time improvment (gas limited on most profiles for 60-70 minute dives)
Infact, I have seen 0 subjective benifit.

I do however have a safer dive. In my neck of the woods nitrox is cheaper than some shops air prices, so I'd have to be a fool not to use it exclusivly.

 

[Aquanaut4ata]

Erm... Actually I only been able to find details of one study into this and the conclusion was that there was no noticable improvement in how people felt after the dive (well, it was actually done in a compression chamber).

On current evidence this is more marketing than fact.

Just a hunch, but doing this test in the chamber probably doesn't accurately replicate factors incurred in diving, like temperature, exertion, etc.
On the fatigue thing.....On a single dive you may or may not notice a difference depending on the parameters of the dive, but I know for a fact that when I do open waters with students, which usually makes for at least 3 dives, some days as many as 6, and doing repeated ascents for CESA, OOA, etc....I feel the difference between air & Nitrox.