Nitrox Certification

[scubadada]

I am considering certifying to dive with Nitrox. I am a warm water recreational diver who is now retired and planning on doing more diving. Most of my diving thus far is during week long dive trips to several different Caribbean islands. Is there really enough benefit gained by a diver like me certifying Nitrox?

Also I noticed I can get certified just by doing an online course. Is this OK, advisable or is there significant advantage to taking the course at a LDS? WHat are the typical costs of such courses. The one I saw for online cert was listed at $89.95 USD.

You're kidding? Of course nitox certificaiton is advantageous. Online certification and analyzing in a shop makes this simple. We used to have to take a relatively rigorous exam and make 2 dives. No brainer.

Sorry, I posted this based on your original post without reading the intervening messages. The feel good message is essentially bull****. You dive to the same exent of NDL(longer) and feel the same (just fine after diving). The big advantage is the longer dives. Incredibly more dives time over multiple dive, multiple days.

 

[highdesert]

The feel good message is essentially bull****.

IMHO, that's not a judgment you can make about any individual other than yourself.

 

[Easdem]

One major benefit of EAN not mentioned here is recovery and feeling after diving. I regularly used to use a 40% mix for all the shallow dives when assisting AOW courses (4 dives, PPB, night, Naturalist, Nav) and air on the deep. using air for all 5 dives on the weekend I would go home tired each night of the weekend and unable to do anything that night. on 40% I'm feeling chipper and OK to see friends and actually have a social life.

The reason that the "major benefit of EAN" is not mentioned, is because its just not true. The Navy Experimental Dive Unit and DAN have done studies on this and found that there was not a significant correlation between tiredness and EANx. That myth continues to be repeated and it is based only on anecdotal evidence. It's probably due to a placebo effect (which can be real).

Here is a nice article on EANx from Alert diver.

Alert Diver | Nitrox

 

[fjpatrum]

The reason that the "major benefit of EAN" is not mentioned, is because its just not true. The Navy Experimental Dive Unit and DAN have done studies on this and found that there was not a significant correlation between tiredness and EANx. That myth continues to be repeated and it is based only on anecdotal evidence. It's probably due to a placebo effect (which can be real).

Here is a nice article on EANx from Alert diver.

Alert Diver | Nitrox

Do you have any links to these studies or even names that can be used to look them up? The article certainly doesn't and this is the first I've ever read or heard of any studies on the correlation of tiredness and EANx.

 

[Easdem]

Do you have any links to these studies or even names that can be used to look them up? The article certainly doesn't and this is the first I've ever read or heard of any studies on the correlation of tiredness and EANx.

There is more on this in the SB archives, but here is a bit. I think it was originally posted by DocVikingo


1. Proceedings of the American Academy of Underwater Sciences 27th Symposium. Dauphin Island, AL: AAUS; 2008.

Measurement of Fatigue following 18 msw Open Water Dives Breathing
Air or EAN36

Scott D. Chapman, Peggy A. Plato

Department of Kinesiology, San Jose State University, One Washington Square, San Jose, CA 95192, USA

"SCUBA divers often report feeling fatigued upon conclusion of diving activities. Post-dive fatigue is thought to be induced by increased energy demands of submersion in a hyperbaric environment and decompression stress. Anecdotal reports indicate a reduction in post-dive fatigue when using enriched-air nitrox (EAN). The purpose of this double-blind study was to compare subjective fatigue levels experienced by SCUBA divers after two repetitive air dives and two repetitive EAN36 dives on separate, nonconsecutive days. Eleven male participants completed pre- and post-dive fatigue assessment using the Multidimensional Fatigue Inventory and a Visual Analogue Scale, while general health was assessed using the Diver Health Survey. Divers did tend to be more fatigued after diving; however, breathing gas mixture exhibited no statistically significant effect."

2. Measurement of fatigue following 18 msw dry chamber dives breathing air or enriched air nitrox. Undersea Hyperb Med. 2003 Winter;30(4):285-91.

Harris, RJ; Doolette, DJ; Wilkinson, DC; Williams, DJ.

"Diving to 18m produced no measurable difference in fatigue, attention levels, ability to concentrate or DHS scores, following dives using either breathing gas."

 

[FinnMom]

As a new diver I noticed that the liveaboads that interested me offered nitrox free. By the end of a 2nd trip the cost of the class is paid and I am still saving money on fills. The math made that a very easy decision.

There are other good reasons to consider it worthwhile (see numerous other posts) but given the above the question was already decided.

 

[Johnmpcny]

Just did 30 dives on Air and our friends did 30 dives on Nitrox in Bonaire. Both of us doing and ave of 3.5 dives a day, we all went to bed early as we had full fun days. Mostly tired from getting in- out and tank, BCD and weight it the same Nitrox or not. Only thing I noticed was they could have flown sooner according to our dive computers. Most dives were started at 60-80 ft and finished at 30-40ft for 50-60 min.

I would have no issues doing it on line. I was helping with their tanks and fully understand how to set my computer for air or gas with the settings needed. The SDA online course goes over all this and tables.

I have to tell you I have a SDA card Got it as a NASDS (1975-76) card replacement as I could not get it replaced after my records (NASDS fire) and card was lost. I have used it on over 50 dives at over 10 dive shops and DM's in USA and Caribbean. Not one has turned me away. A few looked at it twice. BTW I am also have a PADI OW. I just always use the SDA card to prove to you all it is accepted anyplace I have ever dove.

 

[Tigerman]

...
The purpose of Nitrox isn't just to extend dive (bottom) time. Plenty of people dive it on air tables for added conservatism.

A widely believed, but statistically insignificant and entirely theoretical, unproven "fact"..

 

[Damselfish]

Unless you are really strapped for cash, just do it. As said, the major cost is usually fills, not the class. Sooner or later it will probably be useful to you, plus it's some additional knowledge that reinforces what you already learned. Take a legitimate online class or in a shop, whichever works best for your schedule and learning style. Dives don't hurt, but really don't help for this either. I did it when dives were still required, but doing them didn't teach any more about diving Nitrox and can be inconvenient in many cases, so the requirement has mostly gone away.

It's not an either/or between time and conservatism. You can dive Nitrox and use more time than air gives you without pushing it all the way to the Nitrox NDL, so you're getting some of each. Of course it depends on the dive but I suspect that is often what happens naturally for many people.

As far as the tiredness thing, I've heard (probably around here) the theory that this can be caused by bubbling at a subclinical level, which Nitrox would reduce, and that that is why Nitrox helps prevent tiredness for some people. And that proper slow rates of ascent have the same effect, which is why some people will say it makes no difference. It's a theory, thought I'd mention it since I think no one has yet.

 

[Bob DBF]

Undersea Hyperb Med. 2003 Winter;30(4):285-91.

Measurement of fatigue following 18 msw dry chamber dives breathing air or enriched air nitrox.

Harris RJ, Doolette DJ, Wilkinson DC, Williams DJ.



Author information



Abstract

Many divers report less fatigue following diving breathing oxygen rich N2-O2 mixtures compared with breathing air. In this double blinded, randomized controlled study 11 divers breathed either air or Enriched Air Nitrox 36% (oxygen 36%, nitrogen 64%) during an 18 msw (281 kPa(a)) dry chamber dive for a bottom time of 40 minutes. Two periods of exercise were performed during the dive. Divers were assessed before and after each dive using the Multidimensional Fatigue Inventory-20, a visual analogue scale, Digit Span Tests, Stroop Tests, and Divers Health Survey (DHS). Diving to 18m produced no measurable difference in fatigue, attention levels, ability to concentrate or DHS scores, following dives using either breathing gas.

My red highlights to point out that only one "dive" was made. It was a chamber dive, not an actual dive. Only two periods of exercise were done during the "dive".

I am not disputing their results, I don't spring for Nitrox on a three dive day unless I need the bottom time. Where I see a difference is on a 4+ dives per day for a 3 day trip.

Anyone that uses this study to say that Nitrox use does not ever reduce fatigue is extending this study beyond it's limits and including a huge area of study that has never been tested. If one wants to win this argument, don't use a study that is too limited in scope to answer the question in all cases.




Bob
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