Regulator configuration

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Sorry your story sounds a bit strange to me.
A Co2 narcosis? Do you mean a N2? If it realy is CO2 intoxication check your air supplier. The amount of co2 in compressed air is limited normally and not available in percentages being dangerous.
8ft or 2,5 mtr vis is the norm in many parts of the world. Define cold water? When I’m back home the water temp will be down to 7/8dgr C kast winter we dove 4dgr C water and sub zero temp above.
If your computer fails you will surface. How to keep to the 15ft safety stop. Your serious about it otherwise you won’t do it after being passed out and “filled” up on water during a dive. No time and no depth availabe when your comp brakes down.
Even a 2nd stage cut back to nearly closed should give more than enough air even in deep water. As it has been serviced just before, Be very caitious about the shop when it really gave not enough air.
No buddy available during the dive?

Be carefull, you will approach the limit sooner than expected. I’n mynopinion its better to carry a bit more redundancy with you. 2 pound of equipment will not destroy your streamline nor your ballance.

The problem is the human body is a CO2-machine and when the gas density in the lungs increases to around 6g/L, it has a much lessened ability to get rid of it by exhalation.
This can very easily result in CO2-buildup and following narcosis.

6g/L density is roughly equatable to around 30m on air/nitrox, so the narrative does make sense.

The big question is how some organizations teach diving well beyond that limit on air/nitrox without informing their divers about the (very well established) risk they’re being exposed to, as relating to hypercapnia.
 
What can possibly go wrong? With a proper long hose (not what you are considering) Divers Alert Network, Regulator Free-Flow Leads To Failed Buddy Breathing

The only issue I have with that being the example of a bad hand-off is that the problem would have still existed with the normal set up. The panicked diver caused the issue by trying to pull the reg to get more hose. While the donating diver would have still had a reg in their mouth, the change from primary to secondary did not seem to be an issue in the story beyond hoses being tangled and the second reg getting turned upside down.

Or am I missing something?
 
Sorry your story sounds a bit strange to me.
A Co2 narcosis? Do you mean a N2? If it realy is CO2 intoxication check your air supplier. The amount of co2 in compressed air is limited normally and not available in percentages being dangerous.
8ft or 2,5 mtr vis is the norm in many parts of the world. Define cold water? When I’m back home the water temp will be down to 7/8dgr C kast winter we dove 4dgr C water and sub zero temp above.
If your computer fails you will surface. How to keep to the 15ft safety stop. Your serious about it otherwise you won’t do it after being passed out and “filled” up on water during a dive. No time and no depth availabe when your comp brakes down.
Even a 2nd stage cut back to nearly closed should give more than enough air even in deep water. As it has been serviced just before, Be very caitious about the shop when it really gave not enough air.
No buddy available during the dive?

Be carefull, you will approach the limit sooner than expected. I’n mynopinion its better to carry a bit more redundancy with you. 2 pound of equipment will not destroy your streamline nor your ballance.


Yea I was doing my AOW deep dive, limited viz water temp about 52 degrees if i remember and i was in a 7 mil and pretty cold. I was finning heavy and the airflow valve on the second stage was completely screwed in and i did not know it so it had limited airflow at depth.I was not getting enough air so I was likely hyperventilating some. Im guessing I built up alot of CO2 in my bloodstream as I completely blacked out. I woke up staring at my diving buddy with my reg dangling at my side and gulping seawater down my throat not knowing how I arrived in that predicament. I just woke up POW and grabbed reg starting coughing hard into it. I immediately had a feeling of imminent doom and unseen danger. Couldnt shake it, had to focus as hard as I could not to panic. went up from 90 to about 60 and still had the fear which i hadnt had before i blacked out. instructor came up asking if i wanted to go back down to 100 ft floor of ocean "ballbuster 100" in monterey CA and i tried going back down another 10 feet and couldnt shake the feelings. at that point one of the students semi quickly made a beeline for the surface up the anchor chain. I decided to follow him up as i was sure he was narced. I couldnt even get him to do the 3min safety stop. I had him there for a minute then he went full sprint up and into the zodiac.
 
I was thinking of going with something similar to This configuration, but with the 2 regs reversed - I don't understand why they're using the long-hose regulator as the primary, since it would require the buddy who needs help to take the reg out of the other person's mouth, or have it donated. They can't just grab a clipped octo.
Hopefully, from the discussion you have discerned the rationale for the configuration described in the Dive Rite video. It is a very good configuration for recreational diving. (The one thing in the video that DOES NOT make particularly good sense is retention of the yellow purge cover on the bungee necklaced second stage. The yellow should be on the second stage in the diver's mouth.)

My recommendation would be to either a) adopt the configuration as shown in the video, or b) go with the more traditional set-up (alternate on a 40 inch hose, clipped somewhere in the [Bermuda] Triangle, and primary on a 32-36" hose).
Pablo Honey:
Wouldn't it be better for the diver to use the short-hose reg on the necklace as the primary and have the octo clipped in front as usual?
No. As several posters have pointed out, the idea of the configuration is to support 'primary donate'. And, OW training is moving in the general direction of active donation of an air source (be it primary or alternate) in an OOA situation, and away from passive donation. An OOA diver is likely to be on the edge of, or already in, panic, and what that diver doesn't need is a chance to play hide and seek with an alternate clipped 'somewhere' in the triangle.
 
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