Should I do Padi Deep before TDI deco & Adv Nitrox

[Dive-aholic]

Okay. I took your post a different way than intended (obviously!).

 

[Thalassamania]

Meng.....To clarify, going into deco when diving @ 100ft and below you should have He in your mix unless, Your exposure @ 100ft is very limited. Anything below 100ft and there should be some He regardless of exposure. My statements are not wrong. Just safer.At shallow depth,above 100ft I dont see the need.

With all due respect ... you are not wrong to want a Helium mix below 100 feet. And I am not wrong to dive air below 100 feet. And you are not "safer" than I am, but you maybe "safer" than you'd be.

 

[BarryNL]

He never pushed my hard into PADI deep or tried to sell me split fins and snorkel just suggested it would make a good stepping stone, and that he would provide me with a lot of extra training and theory; specifically for me diving on doubles.

Still I'd be interested to hear peoples views.

I'd skip the deep speciality and go straight to advanced nitrox/deep air. Anything useful in 'deep' should be covered in more detail in the other courses anyway.

Personally, I skipped deep and went straight to the DSAT Tec Deep course - theoretically the deep speciality is a requirement for this course but my instructor didn't see any point in doing it.

 

[BarryNL]

With all due respect ... you are not wrong to want a Helium mix below 100 feet. And I am not wrong to dive air below 100 feet. And you are not "safer" than I am, but you maybe "safer" than you'd be.

..and you would be safer with helium than you are on air

Then again, you'd be safer staying out of the water in the first place. It's all a question of how much risk you're comfortable with. Personally, I'm more than happy to do 130ft on air in good conditions (reef dives, etc) but I wouldn't want to do wreck penetrations even at 100ft without helium (well, ok, and without getting trained too).

 

[Thalassamania]

..and you would be safer with helium than you are on air

Then again, you'd be safer staying out of the water in the first place. It's all a question of how much risk you're comfortable with. Personally, I'm more than happy to do 130ft on air in good conditions (reef dives, etc) but I wouldn't want to do wreck penetrations even at 100ft without helium (well, ok, and without getting trained too).

Depth effects everyone, and the effects are different for everyone. I known divers who quite literally could not function at 100 feet on air, I know others who do well with depth, even down to 190. Sure, there are variabilities from dive to dive and day to day, but as a general rule I do not gain enough from mix to make it worth while. I make a switch to mix in the 150 to 190 range, not for sobriety (which I'm sure would become a factor soon) but for decompression and ppO2 considerations. Moving to mix for higher risk dives like wreck penetrations makes sense to me.

 

[fweber]

..and you would be safer with helium than you are on air

I'm sorry if this seems pedantic, but, one gas is not "safer" than another. There is no free lunch and each choice comes with some tradeoff. In the case of helium it would be it's high diffusion rate amongst other things. I can't help but feel that a false "safety" is frequently used to justify peoples choices, not just of gas, but in equipment concerns as well.

 

[BarryNL]

Sure, there are variabilities from dive to dive and day to day, but as a general rule I do not gain enough from mix to make it worth while. I make a switch to mix in the 150 to 190 range, not for sobriety (which I'm sure would become a factor soon) but for decompression and ppO2 considerations.

Must be my education in psychology, but I prefer to rely on experimental evidence even when it seems to conflict with personal experience. Experiments have shown that as people are more regularly exposed to narcosis they notice the effects less and believe it affects them less, but nevertheless still show the same impaired performance in tests as in the beginning.

Something to bear in mind...

 

[Thalassamania]

Must be my education in psychology, but I prefer to rely on experimental evidence even when it seems to conflict with personal experience. Experiments have shown that as people are more regularly exposed to narcosis they notice the effects less and believe it affects them less, but nevertheless still show the same impaired performance in tests as in the beginning.

Something to bear in mind...

And when you've spent time as a subject of those tests you learn things about your own performance. Experiments have shown (as is expected) a normal distribution of response. The question is where do sit on the curve.

 

[Meng_Tze]

Meng.....To clarify, going into deco when diving @ 100ft and below you should have He in your mix unless, Your exposure @ 100ft is very limited. Anything below 100ft and there should be some He regardless of exposure. My statements are not wrong. Just safer.At shallow depth,above 100ft I dont see the need.

I believe your original statement was:

..... Also any class that takes you deeper than about 100 ft or into deco without helium in your mix is just wrong. The last thing you want is to be narked,at depth,and have a problem. ....

That statement is wrong..... 100ft or into deco. You can do dives to/beyond 100ft safely without being narced without He. He is NOT a prerequisite for deco diving. Sorry, but your statement is wrong.

But in a later post (see above) you revert to 'safer' so...safer how?
@100ft, on 32%, you END (just looking at N2) is about 80ft......adding He, will bring that END more shallow.

Let me turn this around. Why should you have He in your mix for deco dives at 100ft and below?

 

[BarryNL]

That statement is wrong..... 100ft or into deco. You can do dives to/beyond 100ft safely without being narced without He. He is NOT a prerequisite for deco diving. Sorry, but your statement is wrong.

Yeah, he might want to take that up with PADI/DSAT - their Tec Diver course teaches deco diving to 165' on air.

Pretty good course I thought. Of course, it probably would be safer with helium - the real question is how safe is safe enough, and that's something everyone has to decide for themselves.