History of the agencies

[Akimbo]

I have an Abalone Diver friend (well once was back in the glory days) who used to dive for hours, yes hours at 30ft or so on SSo2 collecting Abs.

The current US Navy's no decompression limit for 30'/9.14m is 371 minutes/5.98 hours: US Navy Diving Manual, Revision 7A, 2018, Table 9‑9. Air Decompression Table, page 9-65, Adobe page 381. In practice, commercial ab divers have a meandering dive profile that varies quite a bit following the bottom profile.

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For other readers:​

That table is based on 30' +/-0 tested on divers in decompression chambers. Theoretically, any time spent at less than 30' significantly credits the max bottom time no-D limit, but a computer that is programmed for exceptional exposures is required. There is very little, if any data, to validate recreational decompression algorithms in what the US Navy considers the limit for "Exceptional Exposure".

 

[John C. Ratliff]

I have an Abalone Diver friend (well once was back in the glory days) who used to dive for hours, yes hours at 30ft or so on SSo2 collecting Abs. Imagine what he was thinking when years later I was teaching him his nitrox course and telling him that 45mins @ 6m / 20ft / 1.6ppo2 was the limit for using o2.

When I went through the U.S. Naval School for Underwater Swimmers in 1967, we were given an oxygen tolerance test. The instructors put us into a chamber and took us to 66 feet. Then we breathed pure oxygen at that depth for, I think, 15 minutes. Instructors were in the chamber with us, and we had one person go unconscious (his mask was immediately removed). But that test was to look at our ability to tolerate high pressures of oxygen. I don't know whether it is still done.

SeaRat

 

[Superlyte27]

BS re now bolded. Some people got themselves killed, the founder (Hal Watts) / PSA didnt kill anybody. Without what Hal / PSA taught some people, even more people would have killed themselves (doing what they were going to do anyway). And some folks got so 'scared' on their Grotto dive, or their 300ft ocean dive, they never deep aired again. Besides, not like you needed a cert to do "stupid deep" air dives!

How about the 16 year old that he took to 300’ in mystery sink? Let’s talk about that one, then we can discuss some of the others.

 

[BoltSnap]

Let’s talk about that one

Ok, talk and tell us the FACTS that you know.

 

[Superlyte27]

Ok, talk and tell us the FACTS that you know.

Sinkhole closed for diving 1 of 2

Clipping found in Orlando Evening Star published in Orlando, Florida on 8/22/1970. Sinkhole closed for diving 1 of 2

www.newspapers.com

 

[Akimbo]

But that test was to look at our ability to tolerate high pressures of oxygen. I don't know whether it is still done.

I believe that @Duke Dive Medicine mentioned that the oxygen tolerance test was discontinued in the USN because it was not a reliable predictor. Maybe he can refresh my memory as to the "why"?

 

[Superlyte27]

I believe that @Duke Dive Medicine mentioned that the oxygen tolerance test was discontinued in the USN because it was not a reliable predictor. Maybe he can refresh my memory as to the "why"?

It was discontinued 11/98 in the USA. In the private sector, I ran the last chamber to run the 60’ on 100 Percent for 30 minutes. The reason was because the test held no value. You could pass the test today and fail it next week, for no discernible reason.

 

[John C. Ratliff]

I believe that @Duke Dive Medicine mentioned that the oxygen tolerance test was discontinued in the USN because it was not a reliable predictor. Maybe he can refresh my memory as to the "why"?

I didn't say that it was a valid test, only that I accomplished it as part of our training through the U.S. Naval School for Underwater Swimmers, Key West, Florida in 1967. It was in relationship to us using oxygen decompression starting at 40 feet during the Warm Mineral Springs Underwater Archaeological Project in 1975. At that time, this was state-of-the-art for decompression from air dives to just over 200 feet.

SeaRat

 

[Akimbo]

I didn't say that it was a valid test, only that I accomplished it as part of our training through the U.S. Naval School for Underwater Swimmers, Key West, Florida in 1967.

I didn't mean to imply that you did or did not indicate it was a valid test, my apologies if it came across that way. I also did the same test in 2nd class diving school in 1970. We didn't have anyone fail the test in any of the classes while I was there.

 

[rx7diver]

I didn't say that it was a valid test, only that I accomplished it as part of our training through the U.S. Naval School for Underwater Swimmers, Key West, Florida in 1967. It was in relationship to us using oxygen decompression starting at 40 feet during the Warm Mineral Springs Underwater Archaeological Project in 1975. At that time, this was state-of-the-art for decompression from air dives to just over 200 feet.

SeaRat

@John C. Ratliff,

My oxygen exposure table (NOAA) maxes out at 1.6 ATA PO2. Do you have a source for oxygen exposure tables that go up to 3.0 ATA? For purely academic reasons, I am trying to get a sense of the implications on deco if one switches to oxygen at 60 ffw when ascending from a deep air dive to 200 ffw for 30 minutes (say).

TIA,
rx7diver