Enriched Air

[Papa_Bear]

I understand that, but HERE on a Basic SCUBA Discussion board it would be irresponsible to encourage or normalize deep diving for some video! If your going below 197 on air you might as well go get a revolver and try Russian Roulette! It is not recreational diving and belongs in the tech section! Then again tech divers would never do what your doing! So go take the macho deep stuff to the pub!

 

[MaxBottomtime]

Then again tech divers would never do what your doing! So go take the macho deep stuff to the pub!

???
Tech divers wouldn't make tech dives?

 

[MXGratefulDiver]

As you get more experienced, you tend to dive air or migrate to trimix or heliox. Personally the only time I breath Nitrox is of I'm working very shallow, use it as a decompression gas, or diving in the live aboard scenario. Other than that I normally use air or other mixed-gas because I end-up diving outside the safe envelope of Nitrox.

I think you're looking at it more from the perspective of commercial diving. At least my experience is quite different.

Although I will use trimix for dives where it's appropriate to the profile, the vast majority of my dives are made using standard EAN32. This is due to the typical depth and duration of the dives I enjoy doing. On some dives I'll use EAN36, because it'll give me more bottom time in the 75-90 fsw depth I am diving. Trimix and heliox are expensive, and unless you are doing deeper dives (generally below 100 fsw for recreational mix or below recreational depths for tech dives) it's a waste of gas and money.

By far, however, the most benefit you can get from nitrox will be on those multi-dive, multi-day dive vacations that most of us enjoy taking.

I almost never dive air. In fact, I only own two tanks (out of 18 singles, two sets of doubles and four deco bottles) that I use for diving air. The rest are either dedicated for nitrox or trimix use.

... Bob (Grateful Diver)

 

[MXGratefulDiver]

I understand that, but HERE on a Basic SCUBA Discussion board it would be irresponsible to encourage or normalize deep diving for some video! If your going below 197 on air you might as well go get a revolver and try Russian Roulette! It is not recreational diving and belongs in the tech section! Then again tech divers would never do what your doing! So go take the macho deep stuff to the pub!

The Basic Scuba forum is for all kinds of scuba-related discussions. Max's comments are not the least bit irresponsible ... especially compared to some that I have seen you make recently.

While I don't ever dive below about 40 feet on air, it's a matter of personal choice more than responsibility. There have been, and are, lots of divers who dive deep on air. I won't, because I know what it does to my brain functions. But diving is always about personal choice.

In Basic Scuba, the responsibility is to explain WHY you make those choices. Telling people there's nothing worth seeing below 100 feet is kinda lame ... there's PLENTY to see below 100 feet ... but the important thing to say is that you shouldn't just be going deep for depth's sake. There should be a reason to go there, and you should plan and prepare appropriate to the depth you want to go.

Oh ... and we don't discuss macho deep stuff in The Pub ... mostly we discuss politics.

... Bob (Grateful Diver)

 

[DCBC]

I think you're looking at it more from the perspective of commercial diving. At least my experience is quite different.

Hi Bob,

First I have to admit that I dive air below 40'.

Commercial diving is completely different than recreational diving in-that you have various mixtures on-tap and with surface supply, you have limitless amounts of gas available. That said, commercial divers also use SCUBA commercially and for recreation.

I'm not advocating deep diving here (especially in the Basic SCUBA Discussion area), as most inexperienced divers (and some experienced as well) tend to stay within the Nitrox envelope. On the other hand, a good portion of the experienced divers I've trained or met, have tended to dive outside of the Nitrox envelope (deeper than 110', the 1.4 ATM PPO2 maximum of Nitrox 32).

If you want to dive deeper than 110', you use trimix (or Heliox). As I like to do wreck dives (that are usually not the ones "picked-over" by the masses), this necessitates that I use air or in any event a mixture other than Nitrox. Even if another mixed gas is available (at no charge) I don't bother, unless the dive profile requires it, or the dive is deeper than 200'. The versatility of air is almost twice that of Nitrox, so other than the exceptions I've noted in this and another thread, I dive air.

Most inexperienced divers have poor air consumption, so Nitrox doesn't really provide many benefits to them. They find themselves low on gas and have to surface. The majority of them dive one or two dives a day maximum (unless their on holiday in warm water), so this limits the benefits to Nitrox (for those that are use to doing 4 or 5 dives a day, come to Canada and see if you want to do a 2nd).

When the Diver gets more experienced, many of them want to dive beyond the Nitrox envelope (I'm starting to sound like a recording here)... So all I'm really saying is that Nitrox has a purpose, but it's most often lost on the new diver and many experienced divers (unless they are on holiday, dive shallow, or use it as I do, as a decompression gas).

 

[MaxBottomtime]

The Basic Scuba forum is for all kinds of scuba-related discussions. Max's comments are not the least bit irresponsible ... especially compared to some that I have seen you make recently.
(Grateful Diver)

Thanks Bob. I didn't say I made those dives on air so I was surprised at the comment. I was replying to the comment about nothing to photograph below 80 feet. The best photo subjects I have gotten on video and stills have been in the 50-200'+ range. I love seeing things that not only most people never see, but that even most divers never see.
I had to make a special trip to Catalina last summer because Merry needed a picture of a Garibaldi. After shooting video/photo for the past three decades I didn't have a single decent one.

 

[Guy Alcala]

Hi Bob,

First I have to admit that I dive air below 40'.

Commercial diving is completely different than recreational diving in-that you have various mixtures on-tap and with surface supply, you have limitless amounts of gas available. That said, commercial divers also use SCUBA commercially and for recreation.

I'm not advocating deep diving here (especially in the Basic SCUBA Discussion area), as most inexperienced divers (and some experienced as well) tend to stay within the Nitrox envelope. On the other hand, a good portion of the experienced divers I've trained or met, have tended to dive outside of the Nitrox envelope (deeper than 110', the 1.4 ATM PPO2 maximum of Nitrox 32).

If you want to dive deeper than 110', you use trimix (or Heliox). As I like to do wreck dives (that are usually not the ones "picked-over" by the masses), this necessitates that I use air or in any event a mixture other than Nitrox. Even if another mixed gas is available (at no charge) I don't bother, unless the dive profile requires it, or the dive is deeper than 200'. The versatility of air is almost twice that of Nitrox, so other than the exceptions I've noted in this and another thread, I dive air.

Most inexperienced divers have poor air consumption, so Nitrox doesn't really provide many benefits to them. They find themselves low on gas and have to surface. The majority of them dive one or two dives a day maximum (unless their on holiday in warm water), so this limits the benefits to Nitrox (for those that are use to doing 4 or 5 dives a day, come to Canada and see if you want to do a 2nd).

When the Diver gets more experienced, many of them want to dive beyond the Nitrox envelope (I'm starting to sound like a recording here)... So all I'm really saying is that Nitrox has a purpose, but it's most often lost on the new diver and many experienced divers (unless they are on holiday, dive shallow, or use it as I do, as a decompression gas).

While I agree with much of the above, I will say that some of us will use nitrox as a bottom gas deeper than the 111' MOD for 32%/1.4, for open water diving. It's just a question of having the right mix. A couple of the local shops offer pre-mix 32%, but you can always blend it with air. Others only do partial-pressure blending, but you can easily get any mix you want that way, if rather slowly. I haven't been below 138' yet, but have done two dives to that depth, once on air and once on 28% IIRR (1.45 PO2 Max.)

Granted, in the 130-170 foot range there's relatively little advantage gained and increased risk from using nitrox at between 50%-100% more per fill than air, and the local temps restrict most divers to only 2 or 3 dives per day in any case. Personally, I never use it locally for any depth less than 60', and usually not less than 70'. But most experienced divers around here tend to use steel tanks larger than Al 80s, and combined with our better SAC/RMV than newbies, in the 80'-130' range nitrox does give us useful extra bottom time. And it's sure a hell of a lot cheaper than trimix, although if serious narcosis is an issue for you in that range you'd probably prefer to pay the extra money.

Thinking about it, I use air most of the time for shore dives, and generally only plan to use nitrox when boat diving (square, deepish profiles) or on the one or two local shore dives where I know I'll be in the range where it will benefit me. It's air the rest of the time, and (once I get certified) tri-mix for the beyond rec. depth stuff.

Guy

 

[DCBC]

While I agree with much of the above, I will say that some of us will use nitrox as a bottom gas deeper than the 111' MOD for 32%/1.4, for open water diving...

Hi Guy,

You're right many people push the 1.4 ATM PPO2 limit, but it's not advised. The average recreational diver may not be in the best of condition, or may just have a low O2 tolerance.

Personally, O2 Tox scares the *rap out of me. I've passed out a few times because of too much PPO2 in a chamber; I never saw it coming! At least with narcosis, you have some time and I've been able to deal with it, but it largely depends upon several factors as you're aware.

 

[Guy Alcala]

Hi Guy,

You're right many people push the 1.4 ATM PPO2 limit, but it's not advised. The average recreational diver may not be in the best of condition, or may just have a low O2 tolerance.

Personally, O2 Tox scares the *rap out of me. I've passed out a few times because of too much PPO2 in a chamber; I never saw it coming! At least with narcosis, you have some time and I've been able to deal with it, but it largely depends upon several factors as you're aware.

Oh, I virtually never push 1.4; that was a special case. The guy I was diving with was using 1.5 with a slightly richer mix; but then, members of my dive club including him were doing air dives (no tri-mix) in Chuuk as deep as 217 ft., i.e. 1.59. Personally, I'm leaning to keeping myself under 1.3 if not less, after reading that sobering account in Alert Diver of that 20-something woman cave diver who toxed just under that and died. On air you can go to 139' and still be under 1.1 - AFAIK no one has toxed below that.

But I try and keep it in perspective, and remember that some experienced scuba divers were routinely diving to 300'+ on air with little or no problem not so long ago. Still, that's a little too much like russian roulette for my taste.

Guy

 

[Tigerman]

Well, I know of this guy who found it fun to litterarilly play russian roulette and that went well for a long time too. The one time it didnt it broke up the party pretty quick though..