Should Nitrox Certification require dives....

[MHK]

None of the ox-tox rescue and other issues are taught in most agencies basic nitrox so diving to demonstrate those isnt a valid point at all. In fact for some agencies NO rescue training at all is needed to enroll on a basic nitrox course.

What does that tell you about the class? They tell you that if you violate the MOD you'll likely die, but they leave out the very procedure to rescue you should it happen.. That's the larger picture that the student should be challenging the instructor/agency to answer.. If it can kill you, why aren't you teaching how to solve for it??

Later

 

[TCDiver1]

The issue is still the basic requires no extra skills, no extra equipment and no changes at all to diving so would be asking nothing new of a student at all.

How about basic buoyancy control? How do you know a student can demostrate it, without diving with them? Again, you are trusting someone you never met, that someone else you never met, trained them adequately?

 

[jerryn]

There are two issues here:

1. Should current Nitrox courses be augmented and the standards changed to enhance the safety and use of Nitrox? Mike thinks yes and he has a good point.

2. Given the current courses, do you really need to have dives to show that you can dive Nitrox. I think the answer here is no. Once you demonstrate proficiency in the theory and in analysis of the gas, you have accomplished everything that the current courses require. In none of the courses do you go to the dive site with the wrong gas -- that would be a good exercise -- but it is not part of the course. And there are no requirements for the dives for those courses that require them other than observing the MOD.

On another note, IMHO a 10' violation of MOD from a recreational profile and with recreational FO2's ought not cause a tox incident. If it were to, there would undoubtedly be other health issues involved.

Jerry

 

[MHK]

There are two issues here:

2. Given the current courses, do you really need to have dives to show that you can dive Nitrox. I think the answer here is no. Once you demonstrate proficiency in the theory and in analysis of the gas, you have accomplished everything that the current courses require. In none of the courses do you go to the dive site with the wrong gas -- that would be a good exercise -- but it is not part of the course. And there are no requirements for the dives for those courses that require them other than observing the MOD.

On another note, IMHO a 10' violation of MOD from a recreational profile and with recreational FO2's ought not cause a tox incident. If it were to, there would undoubtedly be other health issues involved.

Jerry

Jerry,

I think when you say the "current" course ..., that is the prevailing point. In order to effecuate change, one has to be willing to reconsider the total picture, not just applying a band-aid. I find it curious that less then 10 years ago the scuba industry was so confused and mystified about diving Nitrox that it banned Nitrox from DEMA. Articles were written by prominent agency Training Directors detailing the dire consequences if Nitrox were to expand beyond the scope of Commercial and Military divers. Dixie Divers had to petition OSHA for waiver requests to allow it's instructors to use Nitrox, and so on.. Now, here we are less then 10 years later and the industry is telling you that Nitrox is so simple that after a few formulas, you can do the class over the internet and never meet with an instructor or ever get in the water.. Was the industry wrong then, or now?? I say they were wrong both times..

Moreover, I disagree with your analysis about a 10' deviation. Specifically, the industry promulgates the theory of "Best Myth" formulas, which as a way to calculate a mythical best mix for a target operating depth. Many agencies still use a PP02 of 1.6, and their Nitrox classes usually provide for up to 40%. It's not that difficult of a stretch to imagine an potential ox tox scenario. While I agree that it should continue to be a rare occurence, that doesn't ignore the fact that we should train for it irrespective. Using that logic, one could extend it to the notion that OOA situations should be rare, so then why bother training for it?

The industry isn't going to change by applying band-aids to systemic problems, and the idea that the agencies promote, which is you don't need to dive and/or do any skills with your students is the problem, the instant case is just one symptom in an overall larger problem.

Regards,

 

[Firebrand]

We can't forget that the issues of oxtox affect everyone differently, such as narcosis. Some people are not as prone to it as others, and therefore a general safe partial pressure is 1.4 atm of O2. NOAA set the PP O2 limit for their scientific divers at 1.6 atm. Where do you draw the line? The recreational limit of 1.4 atm is just that - the recreational limit. I didn't get into diving merely to hold a c-card. I got in it for the sport, and the knowledge base that goes with it. I practice my buoyancy every time i'm in the water, and I'm constantly scanning the area I'm swimming in to maintain my situational awareness.

 

[liberato]

For the basic nitrox class not only are the dives worthless the class itself is of little value. Just read the book, study it, understand it, do all the exercises, do the final, get 100% (if not redo misses), get shown how to analyse at the shop. Only knowledge is being certified not skill. This would be a perfect online course for $50. Compare that to the typical resort Nitrox classes were students do not have time to study the concepts, don't do the excercises, and are coached on the test. Well, at least they get the dives in.

 

[String]

What does that tell you about the class? They tell you that if you violate the MOD you'll likely die, but they leave out the very procedure to rescue you should it happen..

Thats a totally different debate. This thread is as far as i can tell about existing courses and should they require dives. Dipping into the actual syllabus taught and required for a specific class is for a different thread entirely.

 

[String]

How about basic buoyancy control? How do you know a student can demostrate it, without diving with them? Again, you are trusting someone you never met, that someone else you never met, trained them adequately?

Bouyancy control isnt a requirement on basic nitrox courses. The entry requirements assume that is already mastered. It isnt a new or different skill introduced with nitrox - its something that isnt any different from basic open water and so on. Demanding dives for something that isnt part of the course is imho daft.

You either accept that a person meets the minimum requirements for the course or give them an exam before accepting them on a course, assessing them for something that isnt part of the course is pointless.

 

[jerryn]

I think more training is better than less, and better skills are superior to inferior skills, but;

Just to test my theory that it is extremely unlikely for recreational divers (diving inside NDL's) diving recreational nitrox (less than 40 percent) to be adversely affected by a 10' busting of the MOD while solving a problem such as OOA, I ran the following scenario:

5 dives on EANx32 separated by 1 hour surface intervals to 110' (1.39 PPO2 approximate MOD for EANx32) with all of the dives going to the limits of the NDL's, but not breaking them. On the last dive, one of the divers runs out of gas just at the end of the NDL time and the two divers, not being very good at this, drop to 120' for 5 minutes before making their ascent.

The model results -- at the end of the 5 dives, including the decompression stops that were required by the extra 5 minutes at depth on the last dive yields:

Max PPO2 = 1.49, CNS clock at 78%, OTU's at 191.

There is nothing here that would indicate that they would tox. By far the greater problem is that they probably would not have enough gas to get them to the surface with the required decompression while air sharing. So they might be in for a chamber ride, but that is not the issue here.

Oxygen toxicity is a non-linear function of both time and PPO2. Perhaps there are some scenarios that would lead to the combination of PPO2's and time that generate a tox incident for recreational divers on Nitrox. I have not been able to come up with any.

Does anyone have any empirical data on ox-tox by recreational divers who are diving within recreational profiles? The theoretical one I gave is pretty extreme -- five tanks of nitrox and five square profiles to max depth with one hour si's.

Jerry

 

[sweatfrog]

For the basic nitrox class not only are the dives worthless the class itself is of little value. Just read the book, study it, understand it, do all the exercises, do the final, get 100% (if not redo misses), get shown how to analyse at the shop. Only knowledge is being certified not skill. This would be a perfect online course for $50. Compare that to the typical resort Nitrox classes were students do not have time to study the concepts, don't do the excercises, and are coached on the test. Well, at least they get the dives in.

Why don't we just send down an ROV to do the dives. Then I don't even have to get my hair wet with that yucky saltwater, worry about NDL's or toxing. GMAB