Is nitrox "briefing" enough without certification?

[Snakekid97]

Hi all,

I have a basic OW certificate with about a dozen OW dives. I recently moved to a coastline, but I haven't gone diving in the ocean in about a year (although I have done a couple of quarry dives since). I recently talked to a local PADI instructor/dive charter owner about easing back into things. After scheduling a date to go out on his charter, I found out they only use nitrox on all of their dives. They claim it's the better way to dive. Their website states " If you are not Nitrox certified, don’t worry, we will give you a Nitrox Briefing that lets you dive Nitrox that day...We will also put a _ Dive Computer on your wrist set for 32% so you can track your NDL."

I have read that I should have a certification for nitrox (which I don't have). My question is: would you trust a "Nitrox briefing that lets you dive Nitrox that day" or does this seem to be a questionable practice? I have no prior experience with Nitrox.

I should add, the charter is a 2-tank trip on reefs 40-60' deep over about a 3-hour period.

Thanks!

 

[Angelo Farina]

You cannot risk hypoxia when diving air or Nitrox in OC.
Hypoxia is a risk just for people using not-pure-oxygen rebreathers, or hypoxic trimix.
Here we are in "new divers and those considering diving", which means OC in either air or low-percentage Nitrox (max 40% oxygen).
Under these conditions, and at shallow depths, all these potential risks are substantially so remote that it is better not alarming new or potential divers with them.
I apologize again for derailing this topic on narcosis, which is not an issue for the OP.

 

[scubaozy]

You cannot risk hypoxia when diving air or Nitrox in OC.
Hypoxia is a risk just for people using not-pure-oxygen rebreathers, or hypoxic trimix.
Here we are in "new divers and those considering diving", which means OC in either air or low-percentage Nitrox (max 40% oxygen).
Under these conditions, and at shallow depths, all these potential risks are substantially so remote that it is better not alarming new or potential divers with them.
I apologize again for derailing this topic on narcosis, which is not an issue for the OP.

Well its not very likely one will experience narcosis diving nitrox on OC due depth limits. Hypercapnia is an actual problem even in shallow depths due increased work like current, poor buoyancy and not being able to ventilate properly and it often does not manifests it self as narcosis.
But agree, I did not notice it was new divers forum, apologies for derailing.

 

[L13]

I remain of my opinion: CO2 is by far the most relevant cause of bad narcosis episodes. Environmental conditions is the second one.

I agree with you on this, though the second (environmental conditions) might actually be due to the fact that bad conditions lead to increased CO2 production.

Not oxygen or nitrogen partial pressure..

There is a lot of evidence for nitrogen narcosis, though as you noted CO2 is likely worse. The primary reason for thinking oxygen was narcotic is a theoretical explanation of gas narcosis, not experimental data. The experimental data suggests that oxygen is not as narcotic as the theory would suggest.

In my experience, CO2 narcosis adds a more "paranoid" feel, while nitrogen narcosis feels slightly euphoric in the absence of CO2 narcosis.

 

[L13]

Well its not very likely one will experience narcosis diving nitrox on OC due depth limits. ...

It is quite easy to experience narcosis on nitrox on OC at recreational depths. On 32% nitrox, the MOD is 33m(111ft), at that depth the equivalent air depth (with regard to nitrogen) is 28m(95ft). It is not uncommon to notice narcosis below 90 feet.

Divers should be alert for nitrogen narcosis on any dive below 25m(80ft) regardless of nitrox%, and alert for hypercapnia at any depth (though depth greatly exacerbates it).

@Angelo Farina is absolutely correct that hypoxia is not a risk for recreational OC.

 

[berndo]

In my experience, CO2 narcosis adds a more "paranoid" feel, while nitrogen narcosis feels slightly euphoric in the absence of CO2 narcosis.

Can you share those experiences you had with narcosis and how you know they were different due to co2 or not?

 

[Angelo Farina]

Can you share those experiences you had with narcosis and how you know they were different due to co2 or not?

I can confirm this. I usually classify narcosis in "happy" and "dark".
The happy one happens during nice dives, with clear water, pretty critters and spectacular landscapes. It requires some significant depth (45m min in my case) and is pleasant, making the diving experience more enjoyable. As the effect is similar to breathing laughing gas (nitrogen peroxyd), I think that explaining it with high pressure of nitrogen and perhaps oxygen is reasonable.
"Dark" narcosis instead usually happens under unfavourable conditions, and it aggravates them, making the diving experience miserable.
I have seen this happening at much shallower depths, just 20m. I personally had a bad hit at 24 m in a cold alpine lake.
It also impairs much more the capabilities of the diver.
Often it is associated with breathing difficulties, which points directly to CO2 accumulation.
I have limited experience of this "dark", narcosis, just one episode in my life. Nothing to do with the euphoric, pleasant drunkness of diving in favourable conditions at 50m..
So, for novice divers at shallow depth, the nitrogen narcosis is not a relevant issue.
Instead the CO2 intoxication (technically called hypercapnia) is a quite relevant risk. It causes not only this bad narcotic effect, but also loss of control on breathing, head aching, panic, and often results in an uncontrolled ascent, as the diver feels so bad that he just want "to be out".
Unfortunately Nitrox does not provide any advantage in preventing hypercapnia.
The proper techniques for preventing it are:
- breathing control, as taught by Cmas, Bsac, etc.
- proper kicking technique with fins suited to the legs of the diver, which avoids over-exertion
- an high performance regulator which reduces the breathing effort
- proper thermal protection (when the body feels cold, it starts burning more for self heating and triggers involuntary muscle contraptions)
- proper weighting (not overweighted), so that the diver is neutral with little or no air in the BCD, making it more easy to stay in trim and streamlined
- a positive, calm state of mind, which favours maintaining proper breathing control, avoiding unnecessary body exertion and moving elegantly and efficiently.

 

[scubaozy]

..

 

[berndo]

I can confirm this. I usually classify narcosis in "happy" and "dark".
The happy one happens during nice dives, with clear water, pretty critters and spectacular landscapes. It requires some significant depth (45m min in my case) and is pleasant, making the diving experience more enjoyable. As the effect is similar to breathing laughing gas (nitrogen peroxyd), I think that explaining it with high pressure of nitrogen and perhaps oxygen is reasonable.
"Dark" narcosis instead usually happens under unfavourable conditions, and it aggravates them, making the diving experience miserable.
I have seen this happening at much shallower depths, just 20m. I personally had a bad hit at 24 m in a cold alpine lake.

I've also had dark narc under unfavourable conditions but in these cases im sure that co2 was no factor. But I did have co2 overload below 30m without being narked at all.
L13 made the claim that in his experience, the co2 causes the dark narc. I wonder if he actually has any experience that would point to this.

 

[L13]

Can you share those experiences you had with narcosis and how you know they were different due to co2 or not?

I have been doing a lot of dives in the 30-40m range lately, probably about 50 dives below 30m in the last 6 months or so. I have experienced what I consider significant narcosis on 2 of those dives, and mild narcosis on a few others.

For one of the 2 significant occurrences, I did an aggressive surface swim and went directly to 33m without properly catching my breath. Narcosis was "Paranoid", but dissipated when I came to 25m and caught my breath before going back down. I blame CO2 + nitrogen.

For the second, I started swimming aggressively at about 30m, and experienced the same "paranoid" narcosis and ended up calling the dive. I blame CO2 + nitrogen.

On the other occasions I have experience narcosis without significant exertion, it was more of a mild "I feel good" feeling, combined with a sense that my thinking was slightly in slow motion and a slight sense of perception narrowing. I generally didn't notice these effects shallower than 30m, but once noticed it at about 25m. I think these were all nitrogen.

Note: I generally don't answer questions from people that don't answer questions(particularly about their experience or location), but decided I want to answer this one anyway.

 

[L13]

L13 made the claim that in his experience, the co2 causes the dark narc. I wonder if he actually has any experience that would point to this.

See my last post.

But, since we are answering questions relevant to experience, here are a bunch that have be asked of you over the last few months by many users on SB that you have ignored:

• Why is your profile locked. It seem like you don't even want people to see your post history. Are you embarrassed by it?
• How long have you been diving? What is your dive count, and how is it distributed across the different types of diving?
• Where are you from/where do you usually dive?
• Which re-breather do you dive, and how much time do you have on it?
• What is your cave diving experience?
• etc., etc. etc,

You frequently questions others experience, but ignore questions about yours. Actual, you conveniently ignore any questions whose answers might be awkward to your point.