Maximum Operating Depth (M.O.D.) S.C.U.B.A. Diving On Air.

[Boston Breakwater]

1. It is indeed SB
2. Many people are really bored due to beervirus
3. OP likes to stir the pot, also consistent with being SB

Hello.
Thas in response to Maxbottomtimes response to tursiops.
And are you new here? SB threads rarely rarely stay on, near or around topic without chasing rabbits, pontificion and wee bit of drama.

The uh, erm, uh MOD of 32% @ 1.4 P02 will be shallower than the same P02 on air and consequently be less narcotic. Phrasing seems pretty clear to me. The difference in potential narcosis between 187' and 111' is pretty significant . Unless I missed something and am entirely incompetent at maths.
Hello. The post has absolutely nothing to do with Nitrox/Enriched air. If, you want to engage me in conversation....you can P.M. me.
Cheers.
This may, or may not constitute stirring the pot.
Would you choose a "Technical." Dive Computer for "Recreational." Diving.

 

[wetb4igetinthewater]

Hello, Everyone. I was curious what the MOD is for air (20.95%) using a PPO2 of 1.4
I'm certain the answers will vary. Is 1.4 a safer single exposure limit than 1.6 or is the difference negligible?
Can you control the effects of elevated partial pressures,
and, are there any warning signs to a possible CNS-02 hit?
Is your exposure expressed as a percentage, or is it a count down in minutes?
Also, what is your "Maximum." depth on air, and what physiological effects did you experience?
Cheers.

While you are talking about air, all of this is covered in nitrox courses, which you have stated you teach. I will assume (and hopefully not make an ass out of u and me) that you have some knowledge in technical diving. I know nothing about you other than the few pieces of information you shared in this thread.

What were you trying to accomplish with this post? As it has gone on for a fair bit with of course some degeneration with insults (standard issue on SB). So what was the point?

 

[Boston Breakwater]

While you are talking about air, all of this is covered in nitrox courses, which you have stated you teach. I will assume (and hopefully not make an ass out of u and me) that you have some knowledge in technical diving. I know nothing about you other than the few pieces of information you shared in this thread.

What were you trying to accomplish with this post? As it has gone on for a fair bit with of course some degeneration with insults (standard issue on SB). So what was the point?

Hello. The post has absolutely nothing to do with Nitrox/Enriched air. If, you want to engage me in conversation....you can P.M. me.
Cheers.

 

[wetb4igetinthewater]

Hello. The post has absolutely nothing to do with Nitrox/Enriched air. If, you want to engage me in conversation....you can P.M. me.
Cheers.

Yes, hence I said you are talking about air. But the answer is found in nitrox and technical diving courses. But you obviously know that. I don't get the point of this, and it is silly to discuss this in PM, so I'll just ignore from now on.

 

[Subcooled]

MOD. Maximum operating depth. A limit of safe diving affected by several factors. Narcosis is one of them and I will give an example below.

I have done a number of dry chamber dives to 6 ATA (50m/164ft). On one occation we had to do this test.

One of the tasks was to connect letters and numbers in the following order: A-1-B-2
And so I did. See?

Another task was to calculate (36+5+2-1)/2

I did the best I could, but I struggled storing intermediate results in my mind, and to store the operation and the second operand, and calculate, and repeat (well, calculations worked well but not the storing part). This task was overwhelming although I had studied mathematics at university for a few years. I just could not remember what I just got as a result. I struggled hard. I was able to proceed with the calculation. I got 36+5=41. I got 41+2=43. But then I had stored the addition operation twice already in my short term memory, and I was unable to overwrite that. So the third operation became an addition too. Result: 44. I did check this immensely complicated calculation, and then I noticed my error and I got a correct result. 42. No. I never noticed that there was a divide by two This highlights what happens when the short term memory is blocked from working. Reasoning that proceeds in steps WILL fail. You MUST memorize your dive, and all emergency procedures, before it begins, or it will fail. I can recall but not store. This is my opinion.

 

[Subcooled]

And I could go on to describe how it feels when the visual signals from your right and left eye arrive out-of-sync and what the ceiling looks like then. Or how long it takes to notice that something (the dive computer) has been beeping for quite some time. Or how it is like to operate a reel when your fingers do not respond to commands immediately. Narcosis sucks. I have had symptoms such as these at the modest depth of 148 feet - on a slow dive without excertion. Visibility was an arms lenght, though.

In good conditions some divers may cope better with the effects, but the effects will be there. Only experience, routines, reflexes will help.

 

[tursiops]

Yes, hence I said you are talking about air. But the answer is found in nitrox and technical diving courses. But you obviously know that. I don't get the point of this, and it is silly to discuss this in PM, so I'll just ignore from now on.

He is just being passive-aggressive. It is hard to take him seriously.

 

[Boston Breakwater]

It is hard to believe that a Nitrox instructor would be asking these questions, unless they are "testing" the readers.
Are these real questions?

Hello @tursiops I firmly believe in thought provoking, and exercising the mind. (Sometimes, with a little curve ball thrown in.) This thread has had over 5000 views.
Regardless, of the "Off-Topic." replies, or the "Posturing" that is somewhat strong on here.........or even the members that didn't reply? It's purpose was to engage thought, and I have seen some extremely good answers...(Including yours.) and then, you know....Off the rails we go. It is really of no consequence. Although, I wish there was a way to see how many post go from
"Baking Cookies." to Brownies, to Apple pie, to Extravagant Covid 338 Triple Layer Cakes?)
A high percentage.........................................probably.
This is from reply #80 in response to @Rose Robinson
Hello, Rose. How are you? I appreciate your response.
I wanted to let you in........on a little secret. Please, don't tell anyone.
I sometimes.........ask questions, that I already know the answer too. Shhhhhhhhhhh. .

Just bear in mind, that my intentions are true, and I'm not here to hurt anyone. I am here to learn, like many other people. I have a long way to go, and try to remain teachable.
I am not the "Best." diver, or the "Worst" diver......Just a "Good." diver.
Cheers.

 

[Boston Breakwater]

Yes, hence I said you are talking about air. But the answer is found in nitrox and technical diving courses. But you obviously know that. I don't get the point of this, and it is silly to discuss this in PM, so I'll just ignore from now on.

Thank you.
Cheers.

 

[Storker]

The post has absolutely nothing to do with Nitrox/Enriched air.

I'm a little surprised that someone who, according to their profile, is EAN certified and an instructor says this.

I'd expect someone with credentials like that to be able to calculate MOD for any standard mix like EAN36, EAN32 and EAN28. Whether it's for 2 bar, 1.6 bar, 1.4 bar or any other pPO2. By extension, I'd expect that person to be able to calculate the MOD for any oxygen percentage, like 34% or 21%.

In other words, I'd expect someone who is EAN certified to be able to calculate the MOD for EAN21 at 1.4 bar O2. Perhaps even be able to reflect on the differences between air and EAN21. Me, I dive both nitrox and air. My PDC is permanently in nitrox mode, and if my tank contains air, I'll just tell my computer that I'm diving EAN21. Not unexpectedly, it gives me the same NDL times as if I told it I was diving air. It doesn't give me the MOD, though, because it doesn't have that functionality in air mode.