Deep Air

Red Sea Explorer · January 27th, 2006, 05:54 PM

I was sitting with an instructor from IANTD and his students yesterday. They are here in the red sea doing an extended range and a trimix course back to back.
Obviously my reaction was:” why not skip extended range and the deep air dives and go directly to Tirmix.” The instructor said something that got me thinking.
He said that he does not allow deep air diving in his club and he always teaches the high helium way. But he refuses to take students deep on trimix before they have a full understanding of what strong narcosis is and how it feels. Therefore he takes the students on the extended range course for deep air dives for them to understand and feel and learn how to anticipate narcosis……then he does the trimix stuff. Even though the students never dive Deep Air after that, it gives them some kind of vision of the other side.
I personally come from the old school and moved to DIR a few years back so I know what narcosis is and I can feel it coming on when I push the mixes. However, it is true that someone who was never exposed might find it uncomfortable and does not know what his reaction will be.
Your thoughts on this...

*JohnKendall* · January 27th, 2006, 06:03 PM

Quote: (Originally Posted by Red Sea Explorer)

I was sitting with an instructor from IANTD and his students yesterday. They are here in the red sea doing an extended range and a trimix course back to back.
Obviously my reaction was:” why not skip extended range and the deep air dives and go directly to Tirmix.” The instructor said something that got me thinking.
He said that he does not allow deep air diving in his club and he always teaches the high helium way. But he refuses to take students deep on trimix before they have a full understanding of what strong narcosis is and how it feels. Therefore he takes the students on the extended range course for deep air dives for them to understand and feel and learn how to anticipate narcosis……then he does the trimix stuff. Even though the students never dive Deep Air after that, it gives them some kind of vision of the other side.
I personally come from the old school and moved to DIR a few years back so I know what narcosis is and I can feel it coming on when I push the mixes. However, it is true that someone who was never exposed might find it uncomfortable and does not know what his reaction will be.
Your thoughts on this...

I have had 2 extreme narcosis events, the first was at 42m in Belize (the blue Hole) I wasn't all that experienced, and didn't realise I was narced however afterwards I realised I was. I still remember nothing of that dive. The other was at 30m in the SETT (a 30m deep training tank) when I did a very fast descent. Since then I've been able to spot narcosis in myself as shallow as 20m. I rarely dive deeper than 20-25m without helium these days. You can get narcosis on fast descents regardless of the mix, so I don't see the need to dive deep on air to get that.

An interesting topic for conversation though.

J

vid · January 27th, 2006, 06:06 PM

i agree, it's better that individuals get a feel for narcosis at depth - say 40M to 45M in a controlled environment with an instructor (& support diver?) on a course, rather than pushing the limits on air (& probably with another inexperienced diver)

given that the range of emotions / outcomes from narcosis can range from mild mental/physical incapacity to absolute fear/panic - i don't even think it's sensible for a single experienced diver to take an inexperienced diver down to that depth on air

vid

Mal Bridgeman · January 27th, 2006, 06:25 PM

I spoke with someone a while ago about this and I understood there was a study into narcosis which showed it was "the rate of change of the ppN2 that caused the narcosis"....which gave a suggested explanation why gently descending down a reef does not cause bad narcosis whereas droppping 50M onto a wreck does.

Anyone know a formal source of this research or similar experience?

Rgrds
Mal

jluttichau · January 27th, 2006, 10:55 PM

Quote: (Originally Posted by Red Sea Explorer)

But he refuses to take students deep on trimix before they have a full understanding of what strong narcosis is and how it feels.

I fail to understand what is to be learned from this?

Cheers
Jonas

Hyper-Limits · January 28th, 2006, 07:13 AM

I took the trimix course because I didn't like the feeling of being narc. and then I find out that I had to take the Extended Range Course first to experience the feeling of being narc. I already made over 200 dives deeper than 130ft on air or Nitrox I didn't need to experience it again to know that it is dangerous and foolish to do so. IMO the Extended Range course should be a thing of the past. It probably made sense in the early 90s when trimix training was hard to come by.

Red Sea Explorer · January 28th, 2006, 10:13 AM

Some times when i am diving standard mixes I get narced either because of decent rate or because I am pushing the mix. I know the feeling and I know what to watch out for.

However if someone is new to it, it can be tricky and it might catch them by surprise.

Petra · January 28th, 2006, 10:38 AM

I can understand why somebody should experience the feelings of being narced so he can appreciate the advantages of trimix (Helium).
But why putting yourself in danger by doing this on a real dive (with or without an experienced instructor on your side)

Why not organise a trip to the decompression chamber where they treat diving accidents?
Believe me you can experience how narced you can get on only 30m. I'm sure you can ask the responsable over there to press you tot 45m....

Red Sea Explorer · January 28th, 2006, 11:54 AM

I doubt that the effects of narcosis are the same in the chamber and in the water.
I agree that it might not be worth the risk to do it.
But in retrospect I would not like to be doing the dives I am doing today if I did not have a good understanding of what it is to be heavily narced.

Mal Bridgeman · January 28th, 2006, 01:20 PM

Quote: (Originally Posted by Red Sea Explorer)

But in retrospect I would not like to be doing the dives I am doing today if I did not have a good understanding of what it is to be heavily narced.

I don't understand your view - Can you explain how it benefits you?

The way I read what you say is a bit like saying "I prefer to drive sober because I know how difficult it is to drive when p*ssed" As Al said recently "I don't need to be hit on the the head by a brick to know I don't want to be hit on the head by a brick".

Mal

January 27th, 2006, 05:54 PM	#1 (permalink)
Red Sea Explorer(Offline) New Member Join Date: Jan 2006 Location: Red Sea Posts: 236	Deep Air I was sitting with an instructor from IANTD and his students yesterday. They are here in the red sea doing an extended range and a trimix course back to back. Obviously my reaction was:” why not skip extended range and the deep air dives and go directly to Tirmix.” The instructor said something that got me thinking. He said that he does not allow deep air diving in his club and he always teaches the high helium way. But he refuses to take students deep on trimix before they have a full understanding of what strong narcosis is and how it feels. Therefore he takes the students on the extended range course for deep air dives for them to understand and feel and learn how to anticipate narcosis……then he does the trimix stuff. Even though the students never dive Deep Air after that, it gives them some kind of vision of the other side. I personally come from the old school and moved to DIR a few years back so I know what narcosis is and I can feel it coming on when I push the mixes. However, it is true that someone who was never exposed might find it uncomfortable and does not know what his reaction will be. Your thoughts on this... __________________ You watch me switch. www.redseaexplorers.com

January 27th, 2006, 06:25 PM	#4 (permalink)
Mal Bridgeman(Offline) New Member Join Date: Nov 2005 Location: Suffolk, UK Posts: 662	I spoke with someone a while ago about this and I understood there was a study into narcosis which showed it was "the rate of change of the ppN2 that caused the narcosis"....which gave a suggested explanation why gently descending down a reef does not cause bad narcosis whereas droppping 50M onto a wreck does. Anyone know a formal source of this research or similar experience? Rgrds Mal __________________ Opinions and beliefs are correct at the time of posting but are subject to change without any notice or obligation on the part of the author.

January 28th, 2006, 10:13 AM	#7 (permalink)
Red Sea Explorer(Offline) New Member Join Date: Jan 2006 Location: Red Sea Posts: 236	Some times when i am diving standard mixes I get narced either because of decent rate or because I am pushing the mix. I know the feeling and I know what to watch out for. However if someone is new to it, it can be tricky and it might catch them by surprise. __________________ You watch me switch. www.redseaexplorers.com

January 28th, 2006, 11:54 AM	#9 (permalink)
Red Sea Explorer(Offline) New Member Join Date: Jan 2006 Location: Red Sea Posts: 236	I doubt that the effects of narcosis are the same in the chamber and in the water. I agree that it might not be worth the risk to do it. But in retrospect I would not like to be doing the dives I am doing today if I did not have a good understanding of what it is to be heavily narced. __________________ You watch me switch. www.redseaexplorers.com

January 28th, 2006, 01:20 PM	#10 (permalink)
Mal Bridgeman(Offline) New Member Join Date: Nov 2005 Location: Suffolk, UK Posts: 662	Quote: (Originally Posted by Red Sea Explorer) But in retrospect I would not like to be doing the dives I am doing today if I did not have a good understanding of what it is to be heavily narced. I don't understand your view - Can you explain how it benefits you? The way I read what you say is a bit like saying "I prefer to drive sober because I know how difficult it is to drive when pssed" As Al said recently "I don't need to be hit on the the head by a brick to know I don't want to be hit on the head by a brick". Mal __________________ Opinions and beliefs are correct at the time of posting but are subject to change without any notice or obligation on the part of the author. Last edited by Mal Bridgeman; January 28th, 2006 at 01:21 PM. Reason: missing letters!*

January 27th, 2006, 06:03 PM	#2 (permalink)
JohnKendall(Offline) GUE Instructor/DIRX Moderator Join Date: Nov 2005 Location: Cambridge, UK Posts: 1,102	Quote: (Originally Posted by Red Sea Explorer) I was sitting with an instructor from IANTD and his students yesterday. They are here in the red sea doing an extended range and a trimix course back to back. Obviously my reaction was:” why not skip extended range and the deep air dives and go directly to Tirmix.” The instructor said something that got me thinking. He said that he does not allow deep air diving in his club and he always teaches the high helium way. But he refuses to take students deep on trimix before they have a full understanding of what strong narcosis is and how it feels. Therefore he takes the students on the extended range course for deep air dives for them to understand and feel and learn how to anticipate narcosis……then he does the trimix stuff. Even though the students never dive Deep Air after that, it gives them some kind of vision of the other side. I personally come from the old school and moved to DIR a few years back so I know what narcosis is and I can feel it coming on when I push the mixes. However, it is true that someone who was never exposed might find it uncomfortable and does not know what his reaction will be. Your thoughts on this... I have had 2 extreme narcosis events, the first was at 42m in Belize (the blue Hole) I wasn't all that experienced, and didn't realise I was narced however afterwards I realised I was. I still remember nothing of that dive. The other was at 30m in the SETT (a 30m deep training tank) when I did a very fast descent. Since then I've been able to spot narcosis in myself as shallow as 20m. I rarely dive deeper than 20-25m without helium these days. You can get narcosis on fast descents regardless of the mix, so I don't see the need to dive deep on air to get that. An interesting topic for conversation though. J

January 27th, 2006, 06:06 PM	#3 (permalink)
vid(Offline) New Member Join Date: Nov 2005 Location: london/surrey border, UK Posts: 353	i agree, it's better that individuals get a feel for narcosis at depth - say 40M to 45M in a controlled environment with an instructor (& support diver?) on a course, rather than pushing the limits on air (& probably with another inexperienced diver) given that the range of emotions / outcomes from narcosis can range from mild mental/physical incapacity to absolute fear/panic - i don't even think it's sensible for a single experienced diver to take an inexperienced diver down to that depth on air vid

January 27th, 2006, 10:55 PM	#5 (permalink)
jluttichau(Offline) Custom User Title Join Date: Nov 2005 Location: Denmark Posts: 437	Quote: (Originally Posted by Red Sea Explorer) But he refuses to take students deep on trimix before they have a full understanding of what strong narcosis is and how it feels. I fail to understand what is to be learned from this? Cheers Jonas

January 28th, 2006, 07:13 AM	#6 (permalink)
Hyper-Limits(Offline) New Member Join Date: Dec 2005 Location: Victoria BC Posts: 16	I took the trimix course because I didn't like the feeling of being narc. and then I find out that I had to take the Extended Range Course first to experience the feeling of being narc. I already made over 200 dives deeper than 130ft on air or Nitrox I didn't need to experience it again to know that it is dangerous and foolish to do so. IMO the Extended Range course should be a thing of the past. It probably made sense in the early 90s when trimix training was hard to come by.

January 28th, 2006, 10:38 AM	#8 (permalink)
Petra(Offline) New Member Join Date: Jan 2006 Location: Brussels Posts: 12	I can understand why somebody should experience the feelings of being narced so he can appreciate the advantages of trimix (Helium). But why putting yourself in danger by doing this on a real dive (with or without an experienced instructor on your side) Why not organise a trip to the decompression chamber where they treat diving accidents? Believe me you can experience how narced you can get on only 30m. I'm sure you can ask the responsable over there to press you tot 45m....