200' on air for 5 min bottom time?

[Dsix36]

Nitrox at 200' ?? Air a 200' already has a PPO2 of 1.48. I can imagine a better suggestion but like you I don't want to hand a gun to anyone.

Yes, you caught me on that one. I should not have posted so quickly.

Nitrox was indeed the wrong choice of wording. Nitrogen enriched air is closer to what I meant. Instead of 20.9% oxygen and 79.1% nitrogen, just raise the nitrogen to about 82%.

 

[Dirty-Dog]

Navy tables ( USN Dive Manual rev6) calculates to 15.1min

• 75fpm decent 2.7 min
  5 min bottom time
  30fpm ascent
  deco stop @ 20' for 1 min
  total ascent time 7.4 min (includes deco)

I also believe it is rather sketchy for a dive plan, but in my youth.....

Intellectual knowledge of Narcosis does not mitigate it's effect. If you are lucky the problem you have while narked will school you rather than kill you but, at 200' on an 80 there isn't much time to learn.

If I recall correctly (and I might not be...) the Navy tables were designed with an acceptable rate of DCS of 1 or 1.5% and with the built in assumption that the diver is a very fit youngster (which would make the risk even higher for the real world).

I prefer a bit more conservatism in this area.

 

[Jared0425]

I have had things go wrong while battling narcosis. It seems that after training up training your reactions are based on your training and the problem can be solved. Newer divers do not have the correct instincts and I agree.

 

[Bob DBF]

If I recall correctly (and I might not be...) the Navy tables were designed with an acceptable rate of DCS of 1 or 1.5% and with the built in assumption that the diver is a very fit youngster (which would make the risk even higher for the real world).

I prefer a bit more conservatism in this area.

Originally it was more like 3% but this was back in when they were using hard hats and a slightly modified version of Haldane's formula. this has been revised a number of times since 1913. Because of the use of SCUBA and not having chambers available at every dive site, the Navy tables for NDL has become more conservative over the years. The tables themselves are not conservative, how you use them can be.

I dove the Navy tables from '63 to '98 without a hit, not scientific but it worked for me. On the other hand there are the undeserved hits using the present tables.



Bob
----------------------------------
I may be old, but I'm not dead yet.

 

[Tigerman]

I have had things go wrong while battling narcosis. It seems that after training up training your reactions are based on your training and the problem can be solved. Newer divers do not have the correct instincts and I agree.

Yeah, and when the problem is one you HAVENT got the muscle memory to deal with? How manageable is that narc then?

 

[sealark]

Yes, you caught me on that one. I should not have posted so quickly.

Nitrox was indeed the wrong choice of wording. Nitrogen enriched air is closer to what I meant. Instead of 20.9% oxygen and 79.1% nitrogen, just raise the nitrogen to about 82%.

What are you thinking raising the nitrogen to 82% ? I wouldn't want you as my supervisor. More narcoses and more deco.

I have made many dives to 200 ft and deeper in my 15 years as a navy diver on air and I was very limited in ability to think correctly. I only have one thing to say, WHY? There is no sense in just doing it without training, experiance and lastley a good reason other than just being able to say I did it.

 

[dumpsterDiver]

Yes, you caught me on that one. I should not have posted so quickly.

Nitrox was indeed the wrong choice of wording. Nitrogen enriched air is closer to what I meant. Instead of 20.9% oxygen and 79.1% nitrogen, just raise the nitrogen to about 82%.

Where do you buy this stuff?

 

[boulderjohn]

Where do you buy this stuff?

I think you can get used rebreather gas on eBay.

 

[Kevrumbo]

If you're going to use a Hypoxic Mix (raising the N2 level to 82% ??? wtf?), might as well partial pressure blend Trimix 18/45, or 20/20 for an economy helium blend.

The OP stated a hypothetical dive on "air" to 200' anyway. .

 

[Dsix36]

What are you thinking raising the nitrogen to 82% ? I wouldn't want you as my supervisor. More narcoses and more deco.

I have made many dives to 200 ft and deeper in my 15 years as a navy diver on air and I was very limited in ability to think correctly. I only have one thing to say, WHY? There is no sense in just doing it without training, experiance and lastley a good reason other than just being able to say I did it.

Where do you buy this stuff?

I think you can get used rebreather gas on eBay.

If you're going to use a Hypoxic Mix (raising the N2 level to 82% ??? wtf?), might as well partial pressure blend Trimix 18/45, or 20/20 for an economy helium blend.

The OP stated a hypothetical dive on "air" to 200' anyway. .

Damn guys, am I the only one with a sense of humor? Don't you know that enriched nitrogen diving is soon to be the newest fad and that everybody will be doing it?