max depth with standard air

[WreckWriter]

I love these deep air discussions. I would like to be able to sent all those who believe that anyone who dives deeper than 80 or 100 feet on air is nuts back in time 25 years to see if they would continue to dive without nitrox and tri mix.

Captain

Oddly enough Cap, that's where some of us came from. I've got hundreds of air dives down to 300' from 1973 to just a few years ago. Now though, I've got better options so I'm not stupid enough to push my luck any farther.

WW

 

[MikeFerrara]

I love these deep air discussions. I would like to be able to sent all those who believe that anyone who dives deeper than 80 or 100 feet on air is nuts back in time 25 years to see if they would continue to dive without nitrox and tri mix.

Captain

I'd dive. I might even dive pretty deep. After all I wouldn't have any other options would I?

But, today, with trimix available how deep do you dive without it? If you love these deep air discussions you should participate.

 

[Scuba_Vixen]

While I have the alternative not to have to dive any deeper than I choose on air, I understand that most folks do not. I don't see anything all that risky in diving to 150' or so on air for an experienced diver with experience in deeper dives and a demonstrated competancy at depth. This also assumes reasonable conditions for such dives.

My issue was more a matter of diving to 150' with the additional risks involved, and doing it in the same gear and with no more specialised training, than you have to do a 40' pretty fishies dive in.

What I got from several posts, was that they saw no issues with diving a purely rec gear setup with only rec level training, as deep as they want to go because they don't want to, or can't afford to, spend what it costs for tech gear and training. I find that mindset extremely dangerous, as it epitomizes the "I don't need to know what I don't already know" road to disaster thought process.

And that does become my business, if some moron wants to do dumb **** and gets hurt or dead,... Then big brother wants to start restricting what all of us can do. I don't want to see it ever come close to that.

Darlene

 

[WreckWriter]

And that does become my business, if some moron wants to do dumb **** and gets hurt or dead,... Then big brother wants to start restricting what all of us can do. I don't want to see it ever come close to that.

Darlene

You got it. Problem is, who decides if its dumb **** or not? Industry standard if we're lucky and that puts the dumb **** line where? 130'.

WW

 

[captain]

I have done many dives in the 130 to 150 zone on air spearfishing under the Louisiana oil platforms with nothing more than basic scuba gear, single tank, no pony, no octo and sometimes times no buddy. Conditions could be as strenous as anywhere in the world. Many times the botton was over 350 feet. My standard procedure was to drop straight down to 150 looking for big fish if there was none it was back in the boat and on to the next platform and do it again. Some divers would drop to 175 to 200 feet looking for big grouper or red snapper. I chose to not chase a fish down to 200 feet on air.
I have no problem with people who use tri mix on dives below 150 feet to explore wrecks or caves. I would like nothing more than to make a tri mix dive on the Doria but at age 59 I don't have the desire to learn or invest in what is required for deep tri mix diving. I have my own compressor so air is cheap and convienent and it serves my needs for the type of diving I do.
Scuba Vixen said its her business when someone does something dumb and ends up dead because the government might get involved. Well more than half of the states don't require adult motorcyclist to where helmets an every year lot more motorcyclist end up dead from being dumb and not wearing a helmet than divers from doing dumb things. Divers would have to be dying by the tens of thousands every year before big brother got involved.
I still take issue with those who believe 150 on air is asking to meet your maker.


Captain

 

[DA Aquamaster]

While I have the alternative not to have to dive any deeper than I choose on air, I understand that most folks do not. I don't see anything all that risky in diving to 150' or so on air for an experienced diver with experience in deeper dives and a demonstrated competancy at depth. This also assumes reasonable conditions for such dives.

My issue was more a matter of diving to 150' with the additional risks involved, and doing it in the same gear and with no more specialised training, than you have to do a 40' pretty fishies dive in.

What I got from several posts, was that they saw no issues with diving a purely rec gear setup with only rec level training, as deep as they want to go because they don't want to, or can't afford to, spend what it costs for tech gear and training. I find that mindset extremely dangerous, as it epitomizes the "I don't need to know what I don't already know" road to disaster thought process.

And that does become my business, if some moron wants to do dumb **** and gets hurt or dead,... Then big brother wants to start restricting what all of us can do. I don't want to see it ever come close to that.

I agree with that statement entirely. I am personally really picky about who I dive deep with in the first place regardless of the gas in use as someone who is inadequately equipped or trained is a threat not only to themselves but to me.

I made the mistake once of taking someone's word about another diver's deep diving abilities in large part because of his reputation as being one of the more skilled members of a local public saftey dive rescue team. So being a nice guy, I buddied with him on a deep air dive as he really wanted to go. On the descent at 130' he developed a water leak in his second stage and panicked. This is, in the whole order of things, a very minor problem with a very simple solution obvious to anyone with a clue about diving. However he panicked and essentially mugged me from behind for assistance.

In my opinion impairment from narcosis as well as its effects in magnifying his anxiety over a relatively dark, low visibility dive in an unfamiliar area and a lack of adequate or recent deep diving experience were all major factors in the incident.

I suspect that with trimix he may have been able to deal with the situation more appropriately. Or maybe not. I was just glad the whole incident occurred at 130' early in the dive rather than at 150' late in the dive with a deco obligation as he continued to panic all the way to the surface and would have went for a chamber ride had it occurred toward the end of the dive.

The whole dive was also to be done on back gas so it would have also left me in an interesting positon at the first deco stop. Do you kick the panicked insta buddy loose to maybe survive an ESA or do you go with him and get bent as well? Given that our local hyperbaric chamber has room for one patient only, it is not a pretty choice.

Consequently, I don't dive below 100' with anyone I do not know really well as I do not want to be placed in the postion of having to potentially make those types of decisions again.

 

[MikeFerrara]

I have done many dives in the 130 to 150 zone on air spearfishing under the Louisiana oil platforms with nothing more than basic scuba gear, single tank, no pony, no octo and sometimes times no buddy. Conditions could be as strenous as anywhere in the world. Many times the botton was over 350 feet. My standard procedure was to drop straight down to 150 looking for big fish if there was none it was back in the boat and on to the next platform and do it again. Some divers would drop to 175 to 200 feet looking for big grouper or red snapper. I chose to not chase a fish down to 200 feet on air.
I have no problem with people who use tri mix on dives below 150 feet to explore wrecks or caves. I would like nothing more than to make a tri mix dive on the Doria but at age 59 I don't have the desire to learn or invest in what is required for deep tri mix diving. I have my own compressor so air is cheap and convienent and it serves my needs for the type of diving I do.
Scuba Vixen said its her business when someone does something dumb and ends up dead because the government might get involved. Well more than half of the states don't require adult motorcyclist to where helmets an every year lot more motorcyclist end up dead from being dumb and not wearing a helmet than divers from doing dumb things. Divers would have to be dying by the tens of thousands every year before big brother got involved.
I still take issue with those who believe 150 on air is asking to meet your maker.


Captain

Thanks for the post. I think 130 is very common and 150 isn't a big stretch. I had to do 170 as part of my training. I know divers who have done accurate cave surveys at 250+ on air and still don't feel the need for helium much above 200 ft.


None of those are my first choice though. I haven't done any spear fishing aside from shooting a few catfish in fresh water but as you point out we're diving wrecks and caves and the smarter and more alert we are the better. That certainly isn't a death sentance for any one who goes below 130 on air. You, me and many other have done it too many times to even make that argument. My only point is that it's better on helium.

Good hunting.

 

[captain]

Below is a table from a 1959 edition of the U S Navy diving manual. As you can see the Navy considered air as a useable gas for normal working dives to 190 feet and 250 feet as a maximum working limit. The limits for SCUBA were primarily based on the duration of the gas supply not the type of gas.
Most SCUBA certifying agencies at the time simply adopted the Navy limits for SCUBA. Over the years the reasons for the limits was some how twisted into a limit on the type of breathing gas and not the duration of the gas supply.
It is apparent from the table that the Navy did not consider using air between 190 feet and 250 feet a major safety issue as long as the air supply was avaliable without limit.

Depth
(feet)
25- Breathing 100% O2or its equivvlent oxygen depth when breathing gas mixtures while working or swimming

36- Non designated diver in an emergency situation

60- Scuba normal working limit (Do not exceed the no decompression limits of table 1-6. The total time of a scuba dive including decompression must never exceed the duration of the apparatus in use disregarding any reserve

60- Lightweight diving equiptment normal working limit (Do not exceed the no decompression limits of table 1-6.

130- Lightweight diving equiment (Do not exceed the no decompression limits of table 1-6.

130- Scuba maximum working limit (Do not exceed the no decompression limits of table 1-6. The total time of a scuba dive including decompression must never exceed the duration of the apparatus in use disregarding any reserve. Certain oprerational swimmers (EOD, UDT) are authorized to dive to greater depths when required.

150- All divers except first class and master.

170- Diving without a medical officer and recompression chamber at the scene (A medical officer and a recompression chamber are required on the scene for all helimun-oxygen diving operations using deepsea equiptment).
Do not exceed the limits of table 1-5.

190- Surface supplied deepsea (air) normal working limit. Do not exceed the limits of table 1-5.

250- Surface supplied deepsea (air) maximum working limit. Do not exceed limits of table 1-9

300- Surface supplied (air) absolute limit. Do not exceed limits of table 1-9

440-Surface supplied deepsea (H2O2) pratical working limit.

Captain

 

[cornfed]

It is apparent from the table that the Navy did not consider using air between 190 feet and 250 feet a major safety issue as long as the air supply was avaliable without limit.

Are you saying that supply should be the determining factor in gas selection?

 

[captain]

No, I am only try to show how some of the limits came into use by recreational divers and how over the years the reasons for the limits have been mis-interpeted into gas type rather than gas supply