40% O2 mix at the safety stop

[Blackwood]

For the sake of brevity, just remember that if you are bringing only one deco bottle, then make sure it is EAN 50 and not 100% O2.

Then you will likely live longer and prosper.

You can make this your personal Rule #2.

Seriously, forget brevity. I'm a little slow, so I need elaboration beyond 'you'll live longer' (though I'm all for prosperity).

 

[nereas]

Seriously, forget brevity. I'm a little slow, so I need elaboration beyond 'you'll live longer' (though I'm all for prosperity).

I like brevity.

 

[Riger]

With due respect to all;

It is my opinion that anyone posting stuff in this thread and quotes any % of O2 or any other gas should also declare their (appropriate certifications) qualifications in the same post.

This forum is often the source of good solid information & guidance, this thread seems to provide some conflicting info.

Best Regards

Richard
AOW, Nitrox

 

[Bismark]

Why ?! 100% O2 on that profile makes perfect sense. You need to take less O2 than 50 and would be out of the water faster.

And maybe more importantly, you will come out cleaner.

 

[MauiScubaSteve]

It is my opinion that anyone posting stuff in this thread and quotes any % of O2 or any other gas should also declare their (appropriate certifications) qualifications in the same post.

That is what your profile page is for. The major players in this thread have given us the pertinent details there. If they have no details there that is also pertinent. Feel free to look at anyone's profile and if they seem lacking, call them on it!

After a few years you know who to disregard, or when to disregard them. Remember, cyber diving is a form of solo diving, and you should have been taught very early on not to believe everything you read!

 

[hypertech]

Maybe next time I'll start out by stating that I am not a tech diver...Bismark and others, you are correct-there is a lot of info but I have a question/observation...several arguments revolve around the divers skill (or lack of). The few dive shops I have talked about regarding a NITROX course are all very proud of the fact that no diving is required in order to get certified for this. "In and out in just a couple of hours" they tell me. So how do they know rather I have normal skills, great skills or just suck?

And on a side note-why even come in at all? Not putting any course down but if it is just that simple then give me the book and charge me to come in and take the test.

I actually don't wish to do it that way-I have been searching for someone in the area who has a good course but can't find anyone. (well, I find people but...)

The course is definately worth while, but I don't understand the big deal about the information presented. It is not rocket science. At the end of the day you realize that most rec profiles don't come near the MOD (in fact the MOD of EAN 32 is the rec limit which is why it is so popular) and it really isn't that big of a deal.

This site does a pretty good job explaining the material: DIR-diver.com - Nitrox Class Part 1

The course does not prepare you for deco, multi gas diving, etc, but I don't really think that is what is being discussed here.

 

[Bismark]

The course is definately worth while, but I don't understand the big deal about the information presented. It is not rocket science. At the end of the day you realize that most rec profiles don't come near the MOD (in fact the MOD of EAN 32 is the rec limit which is why it is so popular) and it really isn't that big of a deal.
.

Again, this is the kind of misinformation which is confusing to someone just becoming familiar with such concepts of MOD, etc. Assuming the rec limit is the same one most people are familiar with (130'), you are presupposing a particular pp02 to get this MOD but you have not told them this. In this case, your pp02 used for your assumption is approximately 1.6. This is higher than recommended for recreational diving by agencies such as PADI or ACUC, etc, and in fact is only "allowed" by most technical agencies for decompression........You may want to revisit your definition of rocket science..........

 

[hypertech]

Again, this is the kind of misinformation which is confusing to someone just becoming familiar with such concepts of MOD, etc. Assuming the rec limit is the same one most people are familiar with (130'), you are presupposing a particular pp02 to get this MOD but you have not told them this. In this case, your pp02 used for your assumption is approximately 1.6. This is higher than recommended for recreational diving by agencies such as PADI or ACUC, etc, and in fact is only "allowed" by most technical agencies for decompression........You may want to revisit your definition of rocket science..........

I didn't post any misinformation - in fact I even linked to a good article describing exactly how to do the one simple calculation needed for MOD.

My nitrox book recommends 1.6 and 1.4 for cold or streneous dives. I took a recreational class. If you look at the CNS table, it doesn't take much convincing to go with 1.4 or 1.5, the so called limit in the book is 1.6. Given that I live in MN, my dives are planned with 1.4 and at the depths I am certified to dive (60' as I have not yet done AOW or Deep Diver - by PADI), it is basically not worth the trouble to even bother with doing it.

Again, using 1.6, or any MOD for that matter, is not some magic number below which you will pop like a bubble.

I guess I'm just not going to understand this idea that regular old people are not capable of doing a little bit of super simple math, asses the risk, and make their own decision about it unless they have done tech training.

 

[Bismark]

I didn't post any misinformation - in fact I even linked to a good article describing exactly how to do the one simple calculation needed for MOD.

My nitrox book recommends 1.6 and 1.4 for cold or streneous dives. I took a recreational class. If you look at the CNS table, it doesn't take much convincing to go with 1.4 or 1.5, the so called limit in the book is 1.6. Given that I live in MN, my dives are planned with 1.4 and at the depths I am certified to dive (60' as I have not yet done AOW or Deep Diver - by PADI), it is basically not worth the trouble to even bother with doing it.

Again, using 1.6, or any MOD for that matter, is not some magic number below which you will pop like a bubble.

I guess I'm just not going to understand this idea that regular old people are not capable of doing a little bit of super simple math, asses the risk, and make their own decision about it unless they have done tech training.

You are partly right and partly wrong. The last bit about regular old people doing this math is exactly correct. Anyone with a calculator can do this stuff, you don't need tech training and I have never said this. However, "garbage in and garbage out" as the old adage goes.

If you are going to post information where less experienced and knowledable people are going to read it and possibly act on it, then I believe you have a responsibility to spell out all the information. You have not done this, and you did not do it again. You are regurgitating bits and pieces of information you have learned with no coherent framework that helps guide someone else in reading your post for the first time, understand clearly what the issues are. Even with the best of intentions which I am sure you have, posting this type of information is incorrect at best and dangerous at worst.

Lets take a look at the whole thing here:

1) Your nitrox "book" which you don't identify claims "1.6 or 1.4 for cold or strenuous dives". Which book is that? We can agree that there is no "magic number" for 02 pp02s. In this case, however, there are some common agency standards (which have moved downward over the years) that are based on statistical analysis of accidents and also based on our best research on 02 toxicity (arguably lacking in this case) I am not aware of any agency that promotes a pp02 of 1.6 for a "cold or strenuous dive" and in fact, it is recommended by many agencies (pick one from the alphabet soup available) that you lower your pp02 maximum for cold and strenuous dives. Many technical agencies (again, pick one) suggest 1.6 as a maximum pp02 to be used only when at rest in decompression. If you have to kick into current, or you are very cold or fatigued, etc., then they recommend lowering that threshhold.

2) Your comment about "popping like a bubble" in regards to high pp02s also shows your lack of understanding about 02 toxicity. 02 toxicity is not DCS and you had best learn the difference. Particularly if you are planning on posting information about it on a public forum.

3) You are correct in saying that for recreational dives in the 60' range, total CNS exposure is pretty much a non event. But do you truly understand why?

Dude, I am not trying to rain on your parade or beat you to death here. I believe you are genuinely trying to help and provide useful information. However, I would suggest that you make sure you have a complete understanding of the entire issue before you recommend anything. The learning process is just that, a process and you are on the path somewhere. Continue asking questions and continue learning but be wary of what you claim as gospel to others. Particularly on a public forum. There is a reason why teachers and instructors require certification and liability insurance in order to teach.

 

[hypertech]

1) I don't have a title of the book with me and didn't mention the agency on purpose so this didn't degrade to a this agency is better than that discussion.

2) Apparently I need to use more smileys as there is no condition I am aware of where you can acutally "pop like a bubble". There ar elots of people who write things like if you do x, y, or z, you will surely die, cease to exist, or "pop like a bubble" as I used it. :0

3) Yes.

If you don't like my organization, just read over the two page article I posted. That pretty much sums up nitrox training and perhaps does it in a format that is better organized. I don't think a special course is needed to read that, understand it, and decide if you want to grab a rich mix at a safety stop.

IMHO, basic nitrox (which is enough to figure out this scenario) should really be included in basic open water training. It isn't that complicated and no more difficult to understand than regular dive tables and DCS. Perpetuating this cloak that it is somehow special just serves to make the training orgs more money by making it a seperate card with a seperate fee. But, they didn't ask me, so two classes, two fees, and two cards it is.