Lite Nitrox at 145

[tursiops]

Thanks everybody for chiming in on a lite nitrox at 145 . My main purpose is to stay a little more clear headed like when a three foot ling cod torpedos in your face then nitrogen narcosis comes into effect and the bumped up O2 may help .

Sorry, the extra O2 is not going to help your narcosis. Pipe dream.

For me, the narcosis at 145 ft on air or Nitrox 26 is enough that I am not really comfortable. I don't mind the WOB.
I'd want some He for the narcosis; reduced WOB is just a side benefit I don't care about at those depths.

 

[Tracy]

Sorry, the extra O2 is not going to help your narcosis. Pipe dream.

For me, the narcosis at 145 ft on air or Nitrox 26 is enough that I am not really comfortable. I don't mind the WOB.
I'd want some He for the narcosis; reduced WOB is just a side benefit I dont' care about at those depths.

What if the WOB was the cause of your Narcosis?
Nitrogen is narcotic, not dismissing that. But CO2 is way way more narcotic and most depth related narcosis comes from the increased WOB at depth. That is how air was divable to somewhat extreme depths back in the days before trimix. You didn't get used to the Narcosis, you learned to control your breathing which lightened the CO2 load and left you with only the nitrogen narc to deal with.
That is why when you watch most people that suffer from narcosis at relatively shallow depths, they also have poor buoyancy and propulsion. They are working harder at those depths and building CO2.

 

[tursiops]

most depth related narcosis comes from the increased WOB at depth

Do you have a citation for this? I'd like to read the studies because that conflicts with my understanding and experience. I'm not denying the contribution of CO2 to narcosis....just that "most" is the correct descriptor.

 

[Tracy]

Do you have a citation for this? I'd like to read the studies because that conflicts with my understanding and experience. I'm not denying the contribution of CO2 to narcosis....just that "most" is the correct descriptor.

I don't. It was something I read in a paper at one point and I started paying attention to it. As someone who used to dive air deeper than current recommendations, thinking back to the bad narc scenarios, they were all on dives where something was happening. Whether it be current or trying to find something specific. The nice calm relaxing dives were just that. Still narced, but workable.

"Most" might not be the correct descriptor. But many and often fit.

 

[tursiops]

I don't. It was something I read in a paper at one point and I started paying attention to it. As someone who used to dive air deeper than current recommendations, thinking back to the bad narc scenarios, they were all on dives where something was happening. Whether it be current or trying to find something specific. The nice calm relaxing dives were just that. Still narced, but workable.

"Most" might not be the correct descriptor. But many and often fit.

My deepest air was 20 years ago to 185 ft (TDI Extended Range course...went slightly too deep!) on the Windjammer in Bonaire. No current, almost no swimming (dropped right on top of it), great viz, no stress.....and almost no memory of the dive. Similar no-memory issues at other air dives 140 and deeper. Felt find during all those dives....but I was clearly narced.

 

[sea_ledford]

Worst narcosis of my life was in 180' on air after sprinting after my buddy for about 5 seconds. Wha-wah city. And I was so completely useless that my buddy (on a ccr with trimix) had to remind me to point the video camera at him to record the substrate test, after he had already started the recording. I'm surprised I remember it.

Not sure if that would have been from WOB, but CO2 is definitely a significant contributor.

 

[Badger7]

Do you have a citation for this? I'd like to read the studies because that conflicts with my understanding and experience. I'm not denying the contribution of CO2 to narcosis....just that "most" is the correct descriptor.

There is a theory is that oil/fat solubility of a gas is a good indicator of its anesthetic/narcotic potential. This proves out rather conveniently for H/He/O2/N2/N20/CHCl3. Carbon dioxide is a whole order of magnitude more soluble in oil/fats than nitrogen and/or oxygen.

https://www.thetritons.com/Library/CO2%20and%20Diving.pdf

Interestingly, O2 should be slightly MORE narcotic than N2 based on its oil solubility, and the common explanation that it is just equally narcotic is that O2 is being used in respiration so its bloodstream levels are being constrained.

There are a few other papers I found on link between CO2 hypercapnia and narcosis, but not necessarily under increased atmospheric pressure, like:

Carbon Dioxide Narcosis - StatPearls - NCBI Bookshelf

www.ncbi.nlm.nih.gov

 

[MaxBottomtime]

On all of the deep air dives I have made, and there were hundreds, the only times I got really narced was from moving the anchor. A buddy told me about stopping, and taking two deep breaths and the CO2 narcosis would subside. It worked. I never had a deep dive where I forgot any portion of the dive.

 

[sandiegoaes]

On all of the deep air dives I have made, and there were hundreds, the only times I got really narced was from moving the anchor. A buddy told me about stopping, and taking two deep breaths and the CO2 narcosis would subside. It worked. I never had a deep dive where I forgot any portion of the dive.

My experience is similar to yours. I have far more deep air dives than helium based dives, simply because of when I started tech diving.

I don't hesitate to add helium whenever I am able to and it makes sense given logistics and cost. On the flip side of the coin, I don't hesitate to use air either in absence of helium availability.

I simply move slow and cautiously on air.

To answer the OP's question, I have dove the USS Hogan extensively (similar wreck and dive profile) and the Moody as well (over 25 years ago).

If you are dead set on using nitrox over helium based mixes, I would simply dive air and do oxygen deco. The extra 5% in a nitrox 26 mix is going to be negligible at best.

 

[SpeedyJ]

Deep air arguments translated: I drove drunk for years, but then Uber came around, so I use that, except when the wait is too long or it's too expensive. Then I drive drunk.