Cavalier858
Guest
on standard compressed air? When do you consider Nitrox?
How deep can you dive safely
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That depends on your training and experience. With nitrox, the richer (more oxygen) the mix the shallower your limit.
JamesK
Contributor
The most general common ground I have found is between 130 and 165 feet. However, the people at each side of the spectrum are VERY vocal about what they feel is safe.
moxie
Contributor
Hi! I sense from your question that you think nitrox allows you to dive deeper than "standard" air. This is a common misunderstanding. Not so! Nitrox has other advantages, such as extended bottom times. It's best to do a lot of research on this yourself, rather than get a quick course off a message board. Take a course at your shop and you'll learn the whole story on risks, such as oxygen toxicity, as well as benefits. I love nitrox and use it whenever I can. But it has risks and you have to have a solid understanding of these before using it.
This is one of those questions that produces more questions than answers.
First is, there is no hard answer as to a safe depth on air. George I. of the WKPP considers air to be unsafe at any depth. Hmm, sounds like a title for a book.
There are lots of factors to consider;
1. Who is diving? training, skill, experience, etc.
2. Why are they diving? look around? collect something? work?
3. What surface support and backup is available? support divers, rescue facilities, location of chamber, etc.
4. SCUBA of Surface Supplied? Surface supplied with a com link or scuba with a wireless com link allows better monitoring of the diver and provides a greater margin of safety.
Now on to some more direct answers.
I have done lots of dives to 130 feet on air but I don't dive that deep anymore on air. I also used to drink alcohol but I don't do that anymore either.
On scuba I will not go deeper than 100 feet on air. I prefer to stay above 70 feet on air.
Nitrox is good to the depth limit for the O2 content. I prefer to use 1.2 ATM PPO2 maximum for diving with a standard regulator and 1.4 if using a full face mask. The use of 1.6 ATM PPO2 is for decompression ONLY and ONLY when resting. O2 tox is one thing that can kill you very quickly and easily. Not that the O2 kills you but the unconsciousness and drowning at depth makes for a very complicated rescue/resusitation. This is why I will allow a higher PPO2 with the FFM, it keeps the divers face dry and supplied with gas so that when you body starts breathing again after the convulsions you breath gas and not water.
For deeper than 100 feet mixed gas with He is the way to go. This requires much greater training and different deco profiles than air. It also requires a much higher standard of care in planning and checking dive gear and procedures before each dive.
I would consider diving to 165' on air only if surface supplied, with a com link, safety diver fully outfitted and ready to go and a deco chamber on site. Then again, that is not SCUBA.
First is, there is no hard answer as to a safe depth on air. George I. of the WKPP considers air to be unsafe at any depth. Hmm, sounds like a title for a book.
There are lots of factors to consider;
1. Who is diving? training, skill, experience, etc.
2. Why are they diving? look around? collect something? work?
3. What surface support and backup is available? support divers, rescue facilities, location of chamber, etc.
4. SCUBA of Surface Supplied? Surface supplied with a com link or scuba with a wireless com link allows better monitoring of the diver and provides a greater margin of safety.
Now on to some more direct answers.
I have done lots of dives to 130 feet on air but I don't dive that deep anymore on air. I also used to drink alcohol but I don't do that anymore either.
On scuba I will not go deeper than 100 feet on air. I prefer to stay above 70 feet on air.
Nitrox is good to the depth limit for the O2 content. I prefer to use 1.2 ATM PPO2 maximum for diving with a standard regulator and 1.4 if using a full face mask. The use of 1.6 ATM PPO2 is for decompression ONLY and ONLY when resting. O2 tox is one thing that can kill you very quickly and easily. Not that the O2 kills you but the unconsciousness and drowning at depth makes for a very complicated rescue/resusitation. This is why I will allow a higher PPO2 with the FFM, it keeps the divers face dry and supplied with gas so that when you body starts breathing again after the convulsions you breath gas and not water.
For deeper than 100 feet mixed gas with He is the way to go. This requires much greater training and different deco profiles than air. It also requires a much higher standard of care in planning and checking dive gear and procedures before each dive.
I would consider diving to 165' on air only if surface supplied, with a com link, safety diver fully outfitted and ready to go and a deco chamber on site. Then again, that is not SCUBA.
Lost Yooper
Guest
Everybody is thoroughly narced when diving air past 100' or so, regardless of whether they recognize it or not and regardless of training level. There is no training that can be done to make deep air reliably safe. The deep air training that does take place simply brainwashes people into thinking they can deal with it. The degree to which narcosis is "felt" may be dependant upon training, but training can't change physiology -- you're still narced and it WILL bite you if it gets a chance.
Nitrox doesn't do much to relieve narcosis -- yes, I know that's what everyone has been told. Oxygen is also narcotic even though it is metabolized. To be on the safe side, don't rely on nitrox to reduce your END. Nitrox is good for you because it has less nitrogen in the mix -- nitrogen is the enemy in decompression. Trimix is the answer to reliably dive safe in deep water.
Take care,
Mike
Nitrox doesn't do much to relieve narcosis -- yes, I know that's what everyone has been told
. Oxygen is also narcotic even though it is metabolized. To be on the safe side, don't rely on nitrox to reduce your END. Nitrox is good for you because it has less nitrogen in the mix -- nitrogen is the enemy in decompression. Trimix is the answer to reliably dive safe in deep water.Take care,
Mike
MASS-Diver
Contributor
I think NITROX is ideal for 50-80' dives. I also think the safe depth for air depends somewhat on the dive condition, but, certianly watching your PPO2 is critical. There seems to be alot of indivdual differences between how different people are affected by nitrogen at depth, so it's hard to set a depth rule based on how narced a diver would be.
I take students down to 100 on their deep dive training. Afrer using trimix on that profile I mixed to a 70 ft equivalent air depth I am changing the way I feel about air diving.
I have gone past 200 on air . Stupid now that I think about it.
If you ever get the opertunity to dive mix past 100 while your buddy is on air you will soon change your tune about how safe air is past 100.
Ron
I have gone past 200 on air . Stupid now that I think about it.
If you ever get the opertunity to dive mix past 100 while your buddy is on air you will soon change your tune about how safe air is past 100.
Ron
MASS-Diver
Contributor
Ron,
I've never dove with TRIMIX, although I can clearly see that in many cases it makes for a much safer dive than air to reduced narcosis and prevent a O2 tox hit. But, is it ture that the helium in TRIMIX takes longer to off gase then nitrogen, leading to shorter no-decompression times than air at depth of 100'? Do I have this backwards? I think I may be confused about this. Thanks
Also, are TRIMIX fills expensive (LDS or your own compressor)?
I've never dove with TRIMIX, although I can clearly see that in many cases it makes for a much safer dive than air to reduced narcosis and prevent a O2 tox hit. But, is it ture that the helium in TRIMIX takes longer to off gase then nitrogen, leading to shorter no-decompression times than air at depth of 100'? Do I have this backwards? I think I may be confused about this. Thanks
Also, are TRIMIX fills expensive (LDS or your own compressor)?
He will ongas and offgas faster than N2.
You will need less total decomp time on trimix than on air but it will be made in many more, shorter stops, starting at greater depth.
For more on this read the articles at;
http://www.wkpp.org/decompression.htm
These are by George I. and are what he is doing on mix doing some amazing dives.
Please don't try to apply the ideas in these articles to air diving. In fact, G.I. indicates that he considers air to be unsuitable as a diving gas.
If you are going deep, trimix or heliox is the way to go.
You will need less total decomp time on trimix than on air but it will be made in many more, shorter stops, starting at greater depth.
For more on this read the articles at;
http://www.wkpp.org/decompression.htm
These are by George I. and are what he is doing on mix doing some amazing dives.
Please don't try to apply the ideas in these articles to air diving. In fact, G.I. indicates that he considers air to be unsuitable as a diving gas.
If you are going deep, trimix or heliox is the way to go.
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