Nitrox for shallow water artifact diving??

[ginti]

He may be diving for 150 minutes or longer but he isn't ever getting anywhere near 1.4 with 20' max depths. Even on that one-of-a-kind 40' dive he did he'd need to be above 60% oxygen to hit 1.4. I don't think ppO2 is going to be a concern for @calabash digger based on his description of the dives he does. He should be below 0.89pp02 if he was using 40%

My point was about using the 1.4 standards. If somebody reads that can believe that standards always safe, and I wasn't sure, this is why I asked

 

[AfterDark]

You missed his point. He knows that. Everyone except AfterDark knows that. He is trying to get AfterDark to admit that nitrox extends bottom time by lowering the amount of nitrogen in the mix. AfterDark keeps denying it.

I never posted it didn't. I got 100% on my nitrox exam. How's the rep dive problem going? Or are you just going to ignore that? A little too much?

 

[AfterDark]

So how does nitrox extend NDLs? We'd all like to know.

Take a class, that's what I did.

 

[tursiops]

Magic
View attachment 664496


I thought you were joking at first. It's a simple matter of reducing your nitrogen uptake by replacing some of the nitrogen with oxygen.

I couldn't say if it's the reduction in nitrogen or increase in oxygen that reduces fatigue. It would be interesting although expensive to do an experiment with 40% nitrox and some 21/19 trimix to discern the answer. I guess it will come down whether the fatigue is being caused by subclinical dcs/nitrogen loading or something else.

@AfterDark seems convinced that nitrox can't have any possible effect above 35 ft because it was invented to extend NDLs, and NDLs are already infinite above 35 ft. I think I am quoting him correctly. He clearly has no idea how nitrox is able to extend NDLs, and ignores the entire subject as just a theory.

 

[Martijn]

Part of this thread is like playing chess with a pigeon...

 

[AfterDark]

@AfterDark seems convinced that nitrox can't have any possible effect above 35 ft because it was invented to extend NDLs, and NDLs are already infinite above 35 ft. I think I am quoting him correctly. He clearly has no idea how nitrox is able to extend NDLs, and ignores the entire subject as just a theory.

No, I just refuse to play your game is all. It just encourages you. Enjoy I'm off to Newport diving on 21% you can read my dive report(s) in the NE section later.

 

[tursiops]

No, I just refuse to play your game is all. It just encourages you. Enjoy I'm off to Newport diving on 21% you can read my dive report(s) in the NE section later.

I'm sorry you think refuting nonsense with facts is a game.

 

[ThatDogDontHunt]

@AfterDark seems convinced that nitrox can't have any possible effect above 35 ft because it was invented to extend NDLs, and NDLs are already infinite above 35 ft. I think I am quoting him correctly. He clearly has no idea how nitrox is able to extend NDLs, and ignores the entire subject as just a theory.

Are NDLs "infinite" above 35ft? Or just so long that most (many, all) 2 dives a day recreation divers can ignore them? Is this a case of the interpretation of a common "rule" now being taken as science?

I found a link to an excerpt from some version of the Navy Dive tables that shows a NDL limit of 595 minutes for 25 feet. I know nothing about Navy Tables and do not know the context of the table shown here
https://umaine.edu/scientificdiving/wp-content/uploads/sites/335/2014/10/Navy_air_tables.pdf
The table does show 10, 15 and 20 foot dives as unlimited NDL.
Or am I confused?

 

[boulderjohn]

Are NDLs "infinite" above 35ft? Or just so long that most (many, all) 2 dives a day recreation divers can ignore them? Is this a case of the interpretation of a common "rule" now being taken as science?

This is AfterDark's claim. I don't know anyone else saying that. My guess, as expressed earlier, is he misunderstands the dive tables.

 

[lowwall]

90 to 120 minutes on a 10 to 25 ft dive. I was taught at these depths there was really no risk of DCS on a two tank dive. ???? I would say 80% of my dives have been in the 20 to 25 ft range and that depth changes up and down a lot sometimes. I climb up and down the wall looking for artifacts so I might be at 25 feet one minute and in five feet of water few minutes later.
I can get Nitrox fills very easily about a mile from my house...couple dollars more I think for each tank...

Given this, I'd take the class. The class will take less time than carefully reading this thread and then you can try it out and decide for yourself. At your depths, there are no safety issues with using the Nitrox mixes you can get with the basic cert (i.e., a maximum of 40% 02). So if it makes you feel better, then use it.

FWIW, I'm one of the people that feels less tired when I use Nitrox. But I've never dived profiles like yours so I have no idea if it would make any difference for me, much less for you

Re the discussion that Nitrox would give you a little bit more of a safety cushion against a freak DCS hit... This is technically true, but the odds are vanishingly small. A better way to avoid any DCS problems given your profiles is simply to make the last 15' of any ascents to or near the surface very slowly. One full, relaxed breath per foot should cover it.