Deep Air Poll

[LFMarm]

Friends, I only use SI units so all good for me.

However, if you want to get more data points (which is typically the purpose of a survey), you would be better off by spending additional 15 seconds and adding the ranges in feet directly in the poll.

 

[Blackcrusader]

Above which blood alcohol content we enter "DUI" territory?

• 0.05%
• 0.08%
• 0.10%
• Etc.

I understand that in some contexts it's necessary to set a fixed limit for the sake of enforcing standards. But in regular diving the point isn't to press right up to the limit and stop: better to use the correct gas instead of pressing your luck and getting into normalization of deviance.

Why don't you start a poll for one. This poll it about air.

Please tell me what the correct gas is for a 32m max depth on a dive.

 

[Germie]

With my cmas 3* cert I can go to 60m on air. That is within the limits of my cert. Newer 3* certs have shallower limits. But they cannot change my limit, even not if it is not written on the cert because it was done in a time of the 60m limit.

With the heliumprices nowadays you see that deep air (40m an deeper) is coming back.

I don't care what people do, but I don't teach the technical diver course (55m on air), as I am responsible as instructor during such dives.
But I really don't like it when people want to decide what gas I am using on a particular dive. I decide myself when doing a fundive.
You don't die when you are going to 30.3m on ean32. The NDL between air on 40m or ean28 on 40m is only 1 minute difference, so for just a longer bottomtime there is no advantage of using ean (I don't talke about the way up).
So what I mean is that I hope this is not a topic to start with pointing fingers if someone goes over 60m on air and others decide that 30m without helium is enough.

There is also a personal factor, some people are always really sensitive for narcosis. Narcosis can be unpredictable, but I have had students who really felt already not well at 33-34m and there we no problems if they did some helium in their breathing gas.
I have been to 52m on air and 'fell in love' with some stupid rocks (that rocks were soooo nice, normally it were just stupid rocks, but now it were very nice rocks, really a nice to spent some time to look at). And decided to do the same dive on the same day again on air and went to 56m, the rocks were still stupid rocks. Nothing happened.

Also the delta P in nitrogen is important for the feeling of the narcoses. The faster you go down, the higher the risk to feel it. And if you wait, the feeling goes away.
I have been to 100m on a 12/55m and on arriving at that depth I felt really the narcoses, so decided to go up again. The end of that gas is not that high, normally I can dive without problems to 55-60m on air. But it was only the rush to go as fast as possible to that depth. I have felt that feeling also when going fast down to 40m. If you go slower or wait a little bit, then it fades away. It is a feeling of nice sleepyness in your limbs, and head. Really relaxing. I know others can feel it different, but for me it is a very nice feeling. I learned from this that I have to resist if the ordered mix is wrong. I ordered a 65% helium and got 54/55. The reaction of the divecenter was: you go easy to 454m on air, aren't you? So then you can go on the 55% to 100m. I thought yes I can do it then. But a next time I want to have around 65% if I order 65%. (I know of course the rule of 5% difference helium and 1% oxygen, but if you just calculate end, it is within my personal limits).
But I don't want to lie that I have done fast ascents because of that feeling later on air (to 40-50m).

So I am not against deep air, and there are no stats showing more accidents in cmas countries where 60-65m on air is quite normal than in places where you expect people use trimix instead. But there are dives were I prefer helium. For myself darkness is no difference, but temperature is.

 

[chrisch]

Please tell me what the correct gas is for a 32m max depth on a dive.

The feet and inches people think you mean petrol

 

[rddvet]

Friends, I only use SI units so all good for me.

However, if you want to get more data points (which is typically the purpose of a survey), you would be better off by spending additional 15 seconds and adding the ranges in feet directly in the poll.

I think 90% of people who have good tech diving experience can quickly figure out meters to feet by simply multiplying by 3.
Firstly there are people from all over the world on the forum.
Secondly if you’re a tech diver and meters is screwing you up, you need to learn to do the math because if you dive outside of the US you will see things like 40s with a 7 on them.
And lastly, learn t pressures and volumes in bar and liters. It will make complex math much easier. And many good instructors are teaching this as part of their course to make well rounded divers. Because tank volume in cubic feet is kind of stupid because it makes for harder math.

 

[ofg-1]

No one told me there would be math.

 

[Germie]

Please tell me what the correct gas is for a 32m max depth on a dive.

Depends on agency. Most will say air or nitrox. But with nitrox some agencies say 1.4 as max PO2, others say 1.5. And this can make a difference in best mix for a nitrox. And if you want to hold the END at 30m, you have to add some helium.

But for me personally it is a gas without helium. At 32m no problems with narcoses.

 

[chrisch]

Depends on agency. Most will say air or nitrox. But with nitrox some agencies say 1.4 as max PO2, others say 1.5. And this can make a difference in best mix for a nitrox. And if you want to hold the END at 30m, you have to add some helium.

But for me personally it is a gas without helium. At 32m no problems with narcoses.

In fairness it depends on a lot of factors. I would suggest a EAN mix at 30% O2 is pretty good choice if you are able to get a blend from the dive shop. Some compressors have a molecular filter and give EAN32 as a standard. Is it a no stop dive? Are you going to use up the remaining gas as part of the next fill? What is the next percentage required? All these factors are important at some level.

So really there is no "correct" gas mix. Air is the cheapest and would work just fine, a little more O2 gives a longer no stop time. Are we planning a second dive?

Gas planning is a useful knowledge but not essential for everyone.

 

[iliketopetsharks]

Gas planning is a useful knowledge but not essential for everyone.

LOL
What's your definition of "gas planning"?

 

[chrisch]

LOL
What's your definition of "gas planning"?

Planning the gas mixture and quantity carried for the dive.