Tech class and narcosis?

[Ouvea]

The depth, at which Narcosis will affect you, differs from each diver. Likewise, the level of mental impairment will differ as well. Personally, I have felt its effects at 100ft. My reaction times suffered and I felt claustrophobic.

GUE recommends 21/35 from 100 to 150ft and 18/45 from 150 to 200ft. Personally, I just use 18/45 for tech dives. Yes, I have a reduced bottom time at shallower depth but I don't care to keep two sets of bottles for each mix.

As mentioned, if you intend on taking GUE Tech 1, you will you need to clear Fundamentals with a Technical rating. If you have already passed Fundamentals with a Recreational rating, you can take Recreational Diver 3, which introduces Trimix and limited decompression.

A good dive team can overcome a mechanical/technical failure, as we have some redundant systems. Losing a team member's mental capacity creates problems on a far greater order/level, as you now have an unknown variable, with which to contend.

 

[ps444mike]

Wow. How did you arrange that? Chamber rides are hard to find

Yes im interested in setting one up out here in calif. any info you could share..

thanks.

 

[Jim Lapenta]

When I teach an AN/DP course we build up to depths over several dives. The AN dives are mostly done shallow (less than 80 ft) to work on skills. When we move to the DP dives it's on the deep side of the quarry and max depth is 135 in the trench. So dives are usually limited to 125-130. A close eye is kept on everyone. We also do not do more than two dives a day beyond 100 ft. First two are NDL dives working on Deco Skills to 100 ft or less. Next 4 are done over two days and are actual decompression dives. Standards limit the amount of deco incurred so depths/times are pretty controlled.
The thing to remember about the course is Deco is not always about going deep (more than 100 feet). If you have the gas and a purpose, a deco dive to 70-80 ft is perfectly within the realm of possibility. Think wreck survey or specific photo opportunity. The instructor is going to be keeping a close eye on the student(s).
In my area - Great Lakes is where most of my students are going to be using it - they may be planning deco dives to 100-110 ft on the wrecks. Helium is nice to have but not always available at a reasonable cost to the person diving. But they still want to spend 25 - 35 minutes on the Dean Richmond at 115 feet. While there is narcosis going on, it's manageable for most of the people doing this because they do it on a regular basis and they are not going to spend 80 bucks on a helitrox fill for this one dive.

 

[Marie13]

Wow. How did you arrange that? Chamber rides are hard to find

Yes im interested in setting one up out here in calif. any info you could share..

thanks.

First you have to find the chamber in your area that accepts divers and go from there. There is only one in my area that does.

ETA: I wanted to clarify that I didn't arrange it. I know someone who did (scheduled it months and months ago), and I was fortunate to be one of the people invited to do it.

 

[elgoog]

Yes im interested in setting one up out here in calif. any info you could share..

USC runs a chamber on Catalina that does chamber dives down to 165ft - Chamber Orientation Dives > USC Catalina Hyperbaric Chamber > USC Dana and David Dornsife College of Letters, Arts and Sciences
They also run one of the best rescue diver courses anywhere; I'm planning on doing both this year.

 

[boulderjohn]

My original tech training was quite obsessive about using helium mixes below 100 feet. I can't even estimate how many tech dives I did in the 100-150 foot range using a mixture that includes helium.

Then I switched agencies and discovered that a whole lot of people do dives between 100-160 feet using air or an appropriate nitrox mix. They seemed to be doing OK.

Then I became a TDI instructor teaching AN/DP, and I never had an issue. I crossed over to PADI and continued with their courses--again, no problems.

 

[northernone]

In the exception of complex navigation I'd not consider adding the complexity and cost of OC trimix to a dive as shallow is 150ft. Having the skills and muscle memory developed to manage gas narcosis during training I believe makes us better divers.

I also find it valuable to know how our body react as part of contingency planning. (Rescues and downwellings)

That said, having an opportunity to clear your head on a few breaths of trimix it's remarkable the amount of clarity that returns.


Regards,
Cameron

 

[uncfnp]

One of my regrets at having the AN and not DP formal course is the loss of the opportunity to dive deeper with an instructor and test my response to narcosis.

 

[seeker242]

Thanks all! Looks like AN/Helitrox would be what I was asking about. I have a GUE Fund rec pass and I'm about 90% of the way to getting a tech pass.

Have you done dives at a depth where you got narked? I wonder because I get a feeling you have very little or no experience at this depth.

I have been at those depths and I certainly did not act stupid down below. However, my speed of thinking slowed down significantly. So, I now how I react to Nitrogen narcosis. Do you too? Just wondering.

No. The deepest I've been to so far is 115' and I didn't feel any noticeable effect. Although, I didn't do any kind of tests for reaction time, etc. I dive mostly with local GUE divers and they don't really go below 100'. I plan of doing a padi deep diver course and the instructor assured me we would be going to 130' so I'm hoping that will give me a better idea as to how I would react.

The thing to remember about the course is Deco is not always about going deep (more than 100 feet). If you have the gas and a purpose, a deco dive to 70-80 ft is perfectly within the realm of possibility. Think wreck survey or specific photo opportunity.

Yes! I'm looking forward to longer bottom times at the wrecks I currently dive around 100'.

 

[KevinNM]

No. The deepest I've been to so far is 115' and I didn't feel any noticeable effect.

I didn't feel any noticeable effect at 130. However I have no memory of looking at my NDL or pressure while I was down there and felt pretty damn task loaded just trying to do a short out and back on a bearing. The tests the instructor did showed that my mechanical type skills (disassemble and reassemble this device) had no change, but the test that required thinking was significantly slower, and it was really frustrating at 130 and simple at 20 feet.