Alarming and Dangerous Incident please read

[Peter84]

I was diving the Tracy in about 75 ft of water off the coast of Ft.Lauderdale, Florida. I had two diving buddies. When we reached the wreck, conditions were good, not great - 40 ft visibility, light current. I was on Nitrox at 36% which was checked at the shop. Upon reaching the wreck I began to expirience a shortness of what seemed oxygen in the mix. I was getting all the volume I demanded of my regulator (Scubapro S600) yet felt like it was not oxygen. Confused I swam towards one of my two buddies which turned into a dash due to the increase deficiency of oxygen. Despite the standard signals I gave him for difficult breathing all I got was a spaced out look from him. Oblivious to what was unfolding right in front of his eyes. At this point I pointed straight up with my hand and bolted up in a semi "controlled panic". I knew that something was deadly wrong, I knew I needed to breath and I needed to reach the surface. I also know that my chances for survival would be in my favor risking the bends or embolism to reach the surface. I was leterally sufficating. At about 30 ft from the surface immediately I started to feel like the oxygen was returned and quickly returned to normal. I went back dowm to find the two individuals diving with me to let them know I was OK and to do a proper gassing off ascent. It seems like I was sucking on nitrogen. Can the gasses separate or layer off in the tanks? I know for a fact that the shop owner does not roll tanks to get proper mix as did the previous owner. Any suggestions, recommendations are deeply appreciated.

Peter

 

[H2Andy]

well... you could have been narced

since when you ascended, things got back to normal

i am pretty sure that when you pump the gas into the cylinders, that will mix them up really good.

when you say you started to experience what seemed like a shortage of oxygen in the mix. can you be more specific as to what you felt and why you thought it meant a shortage of oxygen?

 

[daniel f aleman]

Narced, bigtime. Now you know...

 

[Walter]

I agree with Andy, sounds like narcosis. When you ascend, the partial pressure of the oxygen will drop, so as you ascend, you're getting less oxygen, not more.

 

[Doubles]

well... you could have been narced

since when you ascended, things got back to normal

i am pretty sure that when you pump the gas into the cylinders, that will mix them up really good.

when you say you started to experience what seemed like a shortage of oxygen in the mix. can you be more specific as to what you felt and why you thought it meant a shortage of oxygen?

I would a couple more questions in addition to what Andy has asked you..

Have you refilled that tank yet? If not have you re-analyed it yourself?

If you have the tank and it hasn't been refilled yet, I would definately analyze it again and I would use a different analyzer than the shops.

You mention that you "went back down", did you go to the same depth previously achieved or was it a shallower depth?

Anything else like excessive current, what was your physical condition for that particular dive etc...

Cheers

 

[PerroneFord]

Physics is a killer...

My question is why didn't you begin a share with one of your buddies? And do a normal ascent?

 

[Doubles]

If Peter really had 36% mix then his EAD would be 55 feet.

Do you really think you could have been narced?

Also I reread the post and saw he had little current..

very interesting.

Perrone had a nice point, I would certainly have a chat with my buddies for not taking any kind of supportive action

 

[loosebits]

No, gasses will not seperate but I can't imagine you being narced at that depth either. Could it be a case of simple panic? Regardless you would not notice a lack of O2 in a mix (or at least it wouldn't *feel* like you weren't getting enough O2), you would just pass out and die.

If Peter really had 36% mix then his EAD would be 55 feet.

Do you really think you could have been narced?

O2 is generally considered as narcotic as N2.

 

[DNK]

1] for the most part all nitrox mixes are created by adding o2 to air (21% o2) Partial pressure blending or by removing nitrogen from air (membrane). So unless you are doing some pretty fancy mixes (<21%) there should be no way for you get less than 21% o2.

2] You are talking about stratification, which is (as far as I know has not been proven) when the air (21%) and O2 (partial pressure blending) stratify in the tank, leading to less than accurate o2 measurements (once again 21% is the least common denominator).

So don't think anything was wrong with your gas.

Was this your first ocean dive? where you a bit hesitant?
Sounds like you may have been over breathing, either breathing very fast or shallow, this can cause an excess built up of co2 in your air spaces(lungs, etc). When you ascended you either calmed down and slowed your breathing or by doing the "ahhhhhh" sound blew out your air space. So when you took another breath you got a good lungful of air.

Hope this helps

 

[Ber Rabbit]

I'm going to agree with the others, narcosis sounds like the culprit here. Narcosis can do some funny things but most of it is usually in your head. Training and experience are what will help you keep your head when the narcosis starts "lying" to you. Ascending was a good choice because the narcosis will go away as you ascend however hurrying for the surface wasn't a great choice. You and your buddy should have both started a slow ascent and if you were absolutely convinced the air in your tank was inadequate your fears might have been subdued by using his octopus since you knew he wasn't having breathing problems.

You say the buddy didn't recognize your signal for difficult breathing. The most obvious signals for a breathing problem is to drop your regulator and gently exhale while giving the OOA sign or drop the regulator, grab your buddy's octo, give the "thumbs up" and do a normal ascent. Your buddy would have to be pretty dense to miss the meaning of those.

Really glad you came back from the experience with nothing more than a scare and a lesson learned. Dive safe!
Ber :lilbunny: