Do you think Nitrox is a deep diving gas?

[CompuDude]

Have the standards changed?

When I took AOW in 1995, deep was 60-100fsw. PADI/SSI had an operational max depth limit of 60fsw for OW divers. The deep cert was to extend the student's max bottom to 100/120fsw.

**disclaimer** I answered Are you Nitrox certified?

Mike

Deep Specialty is actually to 130 fsw, but otherwise, yes. PADI's Training limits are 60' for OW, 100' for AOW, and 130' for Deep.

Technically, you're only certified to the conditions and limits you were trained in, but slowly expanding the range as you gain experience is how it's supposed to be done. That said, many dive ops limit the dives they will take OW divers to to sites that are 60' and less, unless they have AOW.

 

[ShakaZulu]

You guys who are tired after a dive is ascending too fast....SLOW it down!

 

[k ellis]

You guys who are tired after a dive is ascending too fast....SLOW it down!

Not really. I actually am very slow to ascend as I try to maximize my submerged time. So its nothing to do with my ascent rate. I do about 50 feet per minute as my target. Slightly less then whats recommended at 60 per minute.

 

[MXGratefulDiver]

Not really. I actually am very slow to ascend as I try to maximize my submerged time. So its nothing to do with my ascent rate. I do about 50 feet per minute as my target. Slightly less then whats recommended at 60 per minute.

That's pretty fast, actually. Most agencies these days recommend 30 fpm.

And keep in mind that the closer you get to the surface the more important it becomes to go even slower, particularly if you were diving fairly aggressively and came close to your NDL's.

ShakaZulu does make a valid point, although like any generalization it doesn't always apply. The most common symptom of bubbling is fatigue ... and that occurs from divers ascending too rapidly. From my observations I would believe it occurs most often due to the ascent from safety stop. That's when the pressure gradient is going to be changing most dramatically with each foot you ascend ... and yet it's when most people rush the dive. It's not uncommon to see people surface from their safety stop in 5 to 10 seconds ... when if you follow the standards most agencies promote, it should take 30 seconds.

Keep in mind that recommended ascent rates stem from mathematical models based on assumptions that may not apply to you. If you're older, not in good physical shape, not well hydrated, tired, stressed, or diving in cold water then you should consider coming up a little slower and see if it makes a difference in your post-dive fatigue. For most "normal" divers today, it will.

... Bob (Grateful Diver)

 

[k ellis]

That's pretty fast, actually. Most agencies these days recommend 30 fpm.

And keep in mind that the closer you get to the surface the more important it becomes to go even slower, particularly if you were diving fairly aggressively and came close to your NDL's.

ShakaZulu does make a valid point, although like any generalization it doesn't always apply. The most common symptom of bubbling is fatigue ... and that occurs from divers ascending too rapidly. From my observations I would believe it occurs most often due to the ascent from safety stop. That's when the pressure gradient is going to be changing most dramatically with each foot you ascend ... and yet it's when most people rush the dive. It's not uncommon to see people surface from their safety stop in 5 to 10 seconds ... when if you follow the standards most agencies promote, it should take 30 seconds.

Keep in mind that recommended ascent rates stem from mathematical models based on assumptions that may not apply to you. If you're older, not in good physical shape, not well hydrated, tired, stressed, or diving in cold water then you should consider coming up a little slower and see if it makes a difference in your post-dive fatigue. For most "normal" divers today, it will.

... Bob (Grateful Diver)

Actually I dont get the fatigue too often. First cause I do dive nitrox which is an added beneifit but mostly cause as you have addressed I am not one to rush the surface. I like to take as long as I can and generally when I do go diving I am among the last to surface if not the last. I just enjoy the surroundings in the water and try to make the experience last.

I do make 3 minute safety stop and usually hang about 5 foot under to allow other divers to utilize the ladder to exit the water first. This also helps add to nitrogen off loading since I have not surfaced yet.

You all do have good points and mine was not too the exact so I apologize. It was just to make the point that the nitrox does assist in less post diving fatigue.

 

[Pacilander]

Kinda depends on your definition of deep.

I would have to agree that it comes down to your definition of deep. Most agencies state that the recreational idea of deep diving is anything over 60 ft. So in this case nitrox could be utilized for deep diving.

Also one other issue is that most divers seem to think that nitrox is only 32%,36% and 40% mix. Divers forget that 22% is still nitrox and has a different MOD.

 

[DandyDon]

When I dove to the sand at the Bibb off Key Largo (137') I used EAN28, as I was at that time only a PADI EAN diver/instructor. After taking my Goliath Grouper picture, I was surprised to turn and find ALL the EAN32 divers impatiently waiting for their turn.

Topside I learned they were all trained by an agency that at that time used 1.6/1.8, so they were only in the contingency portion of their dive. Shortly after that dive I did IANTD instructor crossover training with Dick Rutkowski and was at that time elevated to 1.6/1.8 training.

As the only real work done at that depth was pointing the camera and depressing the shutter, I would have used EAN32 if I had their training.

When was that? I once caught all kinds of hell here for discussing a slip dive to 1.8, no exertion.

 

[MauiScubaSteve]

When I dove to the sand at the Bibb off Key Largo (137') I used EAN28, as I was at that time only a PADI EAN diver/instructor. After taking my Goliath Grouper picture, I was surprised to turn and find ALL the EAN32 divers impatiently waiting for their turn.

Topside I learned they were all trained by an agency that at that time used 1.6/1.8, so they were only in the contingency portion of their dive. Shortly after that dive I did IANTD instructor crossover training with Dick Rutkowski and was at that time elevated to 1.6/1.8 training.

As the only real work done at that depth was pointing the camera and depressing the shutter, I would have used EAN32 if I had their training.

When was that? I once caught all kinds of hell here for discussing a slip dive to 1.8, no exertion.

That was spring of '01. It was on one of the Ocean Divers boats; The inland based group diving 32% was led by their instructor (TDI I think). The Captain was aware of all the gas mixes on board, as the gas was all from OD.

Since the MOD for 32% @ 1.6 is 132', 137' is not much over 1.6

​

 

[halocline]

One of the benefits, often overlooked, of using EAN, at any depth, is the likelyhood of getting DCS is significantly reduced.

There are no good arguments for NOT using Nitrox.

I'll bet someone else has already commented on this, because I have not read the entire thread. There is no proof, NONE, that diving EAN reduces the risk of DCS. There are simply too many other variables and there are no case studies that prove this.

You are making an assumption, which is a good one, that with all other variables equal, a dive with a lower percentage of N2 results in a lower risk of DCS than an identical dive with air. This in itself is just an assumption, although it's pretty well accepted and certainly there are lots of dives that indicate it.

But that's not how most people use nitrox. Personally, I like using it and given a choice I'll use it, but a blanket statement that it reduces DCS risk is not accurate.

The other thing is, I think the idea behind this thread is a little silly. Anyone who has trained for nitrox at all knows that there are MODs for each blend. So to ask "is nitrox for deep diving" doesn't make any sense. It's for diving to the MOD determined by the blend and diver's judgement. Isn't that self evident?

 

[Tigerman]

But the MOD will always be lower than for air, which means you can dive deeper on air as long as youre willing to cope with the deco obligation or shorter NDL..