max depth with standard air

[Don Burke]

Thanks, I'll keep this with me in case I ever go through a time warp to 1959 and want to go diving.

It will be next to the procedures of J.B.S Haldane I keep for a trip to the 1940s.

While I'm in this century, I'll use more current guidance.

Thanks again.

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

 

[Scuba_Vixen]

and that's what those tables were based on. We've come a long way since then, and still have a long way to go. *Yet some how* .... Some aspects seem to still be quite valid.

You notice that for anything deeper than 150', they allow only first class and master divers .... Even back then they realised additional training was required.

Also for depths exceeding 170' ... a medical officer and on site chamber were required ..... Looks to me like they figured there was a significantly greater risk past that point ...

The one thing you neglect to mention was that for the exceptional exposure dives (190' and beyond) *Surface Supplied* that means hard hat/helmet was required. It's a lot easier to survive a cns hit when you don't have a reg in your mouth to spit out ... Which goes back to my point about deep diving on recreational equipment and configurations ...

Actually, from what you posted, they did accept 130' as the limit for lightweight scuba (recreational level) and less than first class or master level training.

Fortunately, almost no one tox's on deep air, (it'a almost always on Ean) The sedative effect of narcosis (high PN2's being present in deep air diving, but absent in ean dives)) being the mitigating factor. So while you may be spared the high risk of oxtox, that *5 martini buzz* is a bit of a handicap when the ka ka hits the fan.

Dive safe,

Darlene

 

[flw]

When I trained 50m was the accepted limit on air, didn't think anything about it - 'course I never got narced either
Of course some of the more interesting wrecks are a peerie bit deeper, so being immortal I dived them on air too. As it happened, I didn't self destruct, nor did I come to any great harm - however it was only when I went back and revisited some of the sites on trimix, I realised that perhaps 60ishm on air is a 'bad idea' - one or two sites didn't look at all familiar second time around.
Every now and again, I look out an old piece of video someone took of me at about 62m making a complete hash of deploying a dsmb, a fact I only realised once I'd looked at the tape and seen that 'fast and clean' had actually taken about 3 or 4 minutes and a spagetti impression.
I now use a rb, so there is no reason not to use heliar diluent on every dive, saves a lot of planning just to leave the same dil in all the time

 

[Lead_carrier]

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.


Captain

But Captain, since then we've started making ships out of steel, flying jets off of ships. Heck, they even have boats that can stay underwater longer than 12 hours. :bonk:

 

[captain]

Scuba Vixen,
FYI in Navy lingo deepsea means full hard hat full dress.

Captain

 

[dbulmer]

Is that a la Village People?

 

[captain]

Current Navy air open circuits scuba requirements

Minimum equiptment
1 Open circuit scuba with J valve or submersible pressure gauge
2 Life preserver or buoyancy compensator
3 Weight belt (if required)
4 Dive knife
5 Face mask
6 Swim fins
7 Wrist watch
8 Depth gauge

Restrictions
Work limits
1 normal 130 fsw
2 Maximum 190fsw with Commanding officer's permission
3 100 fsw with single scuba bottle, twins required below 100fsw
4 Standby diver with twin bottles below 60 fsw
5 Within no-decompression limits
6 Current 1 knot maximum
7 Diving team minimum 4 persons

Advantages
1 Rapid deployment
2 Portability
3 Minimum support requirements
4 Excellent mobility
5 Minimum bottom disturbances

Disadvantages
1 Limited endurance
2 Limited physical protection
3 Influenced by current
4 Lack of voice communications



Yes Lead Carrier they are making ship out of steel but regulators out of plastic. I have more confidence in my all metal Scuba Pro MK 5. Do you think I should switch to plastic.

Captain

 

[cornfed]

Current Navy air open circuits scuba requirements
<snip>
Yes Lead Carrier they are making ship out of steel but regulators out of plastic. I have more confidence in my all metal Scuba Pro MK 5. Do you think I should switch to plastic.

I'm sorry Cap' but you're starting to loose me. What's your point?

 

[Snowbear]

Below is a table from a 1959 edition of the U S Navy diving manual.

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

Captain

They didn't really breath Hydrogen Peroxide, did they? wink

 

[Gibbon]

Restrictions
Work limits
1 normal 130 fsw
2 Maximum 190fsw with Commanding officer's permission
3 100 fsw with single scuba bottle, twins required below 100fsw
4 Standby diver with twin bottles below 60 fsw
5 Within no-decompression limits
6 Current 1 knot maximum
7 Diving team minimum 4 persons

What I see here is that current NAVY requirements for AIR is 130fsw. They can go up to 190fsw, but only with permission, and NOT below 100fsw with only 1 tank.