How Deep Is Air Safe As A SCUBA Breathing Gas?

[drbill]

Darlene- Any time I dive greater than 60 ft I carry a redundant air supply whether it be my pony bottle (solo) or my buddy. Why did you assume the others don't use a redundant air supply?

I've dived 41 (42?) years without touching nitrox or gases other than O-2. Of course I stay away from air filled with LA smog! Now that's unsafe at any depth (including the sirface)! One of the benefits of being on Catalina. (Yes, I know, they filter it).

As for the martini rule, the last time I drank a martini was in 1965 the night before I left for college. My Dad was trying to "teach" me to drink. At 2:00 AM my Mom called down and said to get my father to bed. I told her as soon as I finished the last pitcher!

Dr. Bill

 

[cornfed]

DeepTechScuba once bubbled...

Lets see what YOU believe about this.

http://www.scubaboard.com/t31545/s6147922b95ffe5f2a152b02b3d687684.html

 

[diverbrian]

I do cut down on the effects of the narcosis as a side benefit of diving Nitrox nearly all the time. I have been to 130 ft. on air as part of my IANTD training. If the purpose is to discourage deep air, it worked! I was narced out of my head and didn't enjoy in the least.

I am with the good doctor. Anything that cuts down on N2 is good. I don't have the money for the Helium involved to make trimix or the training to do it, YET. I am looking forward to the day when I do have that. Until then, I limit my diving to 130' ish on EAN28. That appears to work. I will not make the claim that I never get Narced. That would be a lie. But, it seems to minimize it.

Also, I don't check the boxes on polls anymore either.

 

[adder70]

Dr Paul Thomas once bubbled...
Hi again folks,

I fully agree with DTS and Walter, but their perspective seems to be rather special, i.e. training and shallow professional diving.

For those who skipped down, this concerns shallow depths. I believe 20 ft was mentioned. I definitely disagree with calling this a specialty or training depth.

I grew up in Florida, and have had many dives with shallow depths. The springs are mostly around 25-30 feet deep at the deepest OW area, and most of the good stuff to see is around 15 ft. (Yes, snorkeling the springs is, IMHO, a great way to spend a day!) This includes Ginnie and Manatee, I know, and several others as well. Rainbow River provided a full tank (~45-60 minutes depending on tank and breathing habits) dive with a max depth of 22 ft. Most of the dive was actually around 12-15 feet, as the river changes depths, and more fish are near the grasses along the shore than in the "channel" (Is 18 ft a channel?) anyway.

In the ocean, there are quite a few reefs at about 30 ft, some decent wrecks and great reefs at 40-50 ft, and in the Keys you get reefs that come right up to the surface! (side point: take care in tidal areas and surf. It sucks to get dropped by a wave right on a piece of coral, or to find yourself surrounded by surface level coral! Hey, who needs all of their skin anyway, right!)

So I think it is more of a diving topography issue. I guess we have flatter bottoms here so you can see stuff shallow. I guess Florida is flat under water too! I do believe some of the beachfront hotels in Miami actually reach above the highest point in all of Florida! (337 ft, if I recall correctly.)

 

[Wendryn]

I got narced for the first time at 120' in the ocean. My reaction to getting narced is to be completely convinced that something is very wrong. I feel the need to check everything. I have since learned to let that little freaked-out part of my brain chatter away and just do things normally, albeit rather slowly, but I would prefer not to get too narced again. I know I can handle it, but for me, I'll leave the limit between 110' and 120' on air.

Nitrox is good Trimix will be better...

--Wendryn

 

[tinman694]

Don Burke once bubbled...
I chose 100, although complex problems might be too much at about 80 and the closer you get to the no-stop limits, the more potential for damage there is.

Anyone who thinks he doesn't get narced will be very surprised if he tries something like multiplying trinomials at 100 feet.

I can't multiply numbers on the surface!!!

I still remember doing a my first deep dive (at altitude) to 90' (~105 adjusted for altitude) and getting narcosis--It was not fun.

Why is it some people have a chip on their shoulder about "going deeper"? Like "I have 22 dives and have been to 650 feet on air and never have been narced". PLEEZE-- Everyone who did the skill puzzles at 100' in my deep dive class had some impairment.

Still, I have always wondered when there would be a discussion about (non nitrox) mixed gas at shallow depth.

 

[bm9]

I dive air to 130 ft for my recreational dives. While I don't consider this optimal, it has posed no problems for me so far, and it is significantly cheaper where I live.

 

[pt40fathoms]

Any dive below 130' without using Tri-Mix, is a very forgettable dive! Literally!

All divers who say they don't get narced below 60', don't know how to tell if they are narced. Uncle Pug put it best in his reply.

By the time you reach 130' you will be impaired. Be it a slowing of response times, or a lack of awareness, that due to your lack of awareness you are not aware of this lack of awareness.(whew,,,thats a little confusing even at 1 ata) To more noticeable symptoms such as a feeling of dread or panic, a strong desire to "get out". At the other end of the spectrum their can be a feeling of complete comfort and an associated carefree (careless) attitude. Some have reported that they hear music or see pretty colours and even have mild hallucinations. The list of symptoms is long and need not be listed in its entirety.

Bottom line is you will be impaired, whether you notice the symptoms or not. Those who insist they are not, nor have never been narced, just need more experience, or less bravado.

 

[CD_in_Chitown]

pt40fathoms once bubbled...
Some have reported that they hear music or see pretty colours and even have mild hallucinations.

Dude, mild hallucinations are buzzing and tunnel vision or spots. Music and colors are beyond mild into "euphoric" hallucinations.

 

[DeepTechScuba]

As you can see by the shallower choices in the poll, this is actually a SHALLOW AIR discussion and poll, NOT a deep air discussion.

I put the 100', 130', 150', etc choices there just to fill in for those folks who do not have a shallow air appreciation for N2 loading.

The real question in MY mind is when should you switch over to nitrox, at what depth?

In my mind, the answer to that question is either of the following:

1) you always dive on nitrox
2) you dive on ntrox deeper than 20 ft
3) you dive on nitrox deeper than 50 ft
4) you never dive on nitrox

Choice #4 embraces the 130', 150', 170' etc answers BECAUSE you cannot dive on nitrox at those depths. (I am not considering EAN25 as "nitrox" although technically it is I suppose.)

I want to know at what SHALLOW depth divers here will use nitrox instead of air.

This is not a deep air discussion.