What is the Shallowest Depth at which You Notice Narcosis?

[wedivebc]

Using Multideco it alarms on it if I have the following conditions;

60m 22 min 18/40 then change to 32%Nx at 39 metres ppN2 of IBCD setting 0.5 ATA

And I have challenged Ross Hemmingway in the past to offer the same examples and he has been unable to site a single case. When I asked what the basis of his limits used in the software he stated "there has been studies" and "you can set it to whatever you like"

 

[Peter69_56]

I can only use what I have been trained to, given I don't have experience in this area. I was told always <= 0.5 ATA between END levels when changing gases. I always dive conservatively, thus although I understand what you are suggesting, I will go with what I have been trained to. That way I would hope I get to do many more dives without problems.

 

[ajduplessis]

Please site one case of ICD (or more correctly ICD induced DCS) that has occurred at 120ft. Or even shallower than 300ft for that matter. I have never heard of one.

Mark Ellyatt
John Bennett
Pascal Bernabe
Don Shirley. David Shaw's dive buddy in South Africa.

Anything else??

 

[MrChen]

Also, I have briefly felt it at shallower depths but only temporary after a fast descent.

Tim, decent speed affects this?

 

[wedivebc]

Mark Ellyatt
John Bennett
Pascal Bernabe
Don Shirley. David Shaw's dive buddy in South Africa.

Anything else??

Oh you mean all the world depth record setters? And did you actually read my question?

 

[ajduplessis]

4 examples all within your specified parameter range and still the $$&@?$& flows. Our Course director lacks more than just a SB status.

 

[kr2y5]

There is also an example given in this article of what the author would consider to be an unsafe gas switch at 130 feet, along with a formula for it, and a rationale grounded in some physics. Hope this helps.

 

[wedivebc]

4 examples all within your specified parameter range and still the $$&@?$& flows. Our Course director lacks more than just a SB status.

In my question I specified this happening on a dive shallower than 300ft. Are you saying the people you sited experienced IBCD on a dive shallower than 300ft?

 

[Peter69_56]

I would refer you to TDI Advanced trimix Diving Manual page 69-70 Isobaric Counter Diffusion - vestibular hits

"It usually occurs when a diver breathing a mix containing high helium content swaps over to a mix with a high nitrogen loading."

"The issue seemed to be caused when they (professional divers) used tables that called for a switch to air from heliox at about 25m/80 ft."

"Don't switch to gases that cause a sudden increase in the partial pressure of nitrogen and try to avoid air as part of any decompression strategy."

 

[100days-a-year]

If you are switching from heliox to air for deco,there are far greater issues in your life than the miniscule chance of an ICD hit.

BTW what does all this have to do with the perception of narcosis?