Where did the 135 foot / 40 meter recreational max depth limit come from?

[CT-Rich]

When was the recreational limit reduced to 40m?
When I was certified in the seventies, the limit was 50m, and deco was allowed, but only if starting at 9m (that is, three deco stops maximum, 9m, 6m, 3m).
My 3-stars FIPS-CMAS certificate, issued in 1977, fixed my limits for recreational diving at 50m with deco, with buddy, in air, and 10m, within "oxygen safety curve", with buddy, with pure-oxygen rebreather.
I really do not know in which year the maximum depth was reduced from 50m to 40m, and the NDL was enforced as the limit for recreational diving.
So I am asking if someone knows the dates where the various agencies reduced the rec limits...

When I had my NAUI class in 1980, we were taught how to plan a deco dive. In retrospect, I think it was done as part of the completist training of the day. The assumption was always that you learn more from someone with much more experience than you and have a basic theoretical understanding and fill in the cavernous amount of classroom time we had.

 

[rhwestfall]

My 1988 YMCA Scuba Diver certification included planning dives with staged decompression. It also had a recommendation not to exceed 130'.

 

[tursiops]

The 1943 version of the U.S. Navy diving Manual, which was the first version since 1924, has a chapter on Ascent...it was about hardhat divers being cranked up at 25 ft/s. The air deco table shows NO deco time required as follows:
depth NDL
40 ft 130 mins
50 78
60 55
70 43
80 35
90 30
100 25
110 20
120 18
130 15
140 15 but 4 mins deco required at 10 ft

So the cutoff in 1943 was 130 ft.

For comparison, Haldane's original tables gave:
depth NDL
0-30 ft no limit
30-42 over 3 hours
42-48 60 mins
48-54 30 mins
54-60 20 mins
60-66 15 mins
66-72 15 mins but 2 mins deco required at 16 ft

After 1943 the next Diving Manual revision was 1952; I do not have a copy of that.

All recent Diving Manuals since at least Rev 4 (1999) show air no-deco times up to 190 fsw!!
I don't have copies of Rev 1 (1985), Rev 2 (1987), or Rev 3 (not sure this exists), nor of the other related publications between 1952 and Rev 1.

 

[Must_dash]

Just looking at my BSAC manual 7th edition of 1972 based on the Royal Navy Decompression Tables, but no date given
40 ft 135mins
50 85
60 60
70 40
80 30
90 25
100 20
110 17
120 14
130 11
140 9
150 8
160 is the first with a deco of 5 mins at 20' and 5 mins at 10'

 

[scubadada]

My 1970 LA County certification, called Basic Scuba Diving, did not include decompression diving. We did no stop dives using USN tables, steel 72s with J-valves, a capillary depth gauge and a watch.

 

[tursiops]

My 1970 LA County certification, called Basic Scuba Diving, did not include decompression diving. We did no stop dives using USN tables, steel 72s with J-valves, a capillary depth gauge and a watch.

And what did the 1970 (or whatever year they were) table say?

 

[lermontov]

You are just not patient enough. Give them another five minutes and they will be arguing over the middle name of the dog that ate out of the dumpster at the LA YMCA and the influence it had on the process of Laminating dive tables which resulted in the adoption of the color scheme that was adopted by the printer of the first edition of the Science of Scuba diving and resulted in a font choice that limited the number of columns that ended up in only being able to go to 130’ on a page. Hence the 130’ limit.

Thats not correct- it was a homeless person that owned a dog -this is a common misconception and coloured tables didnt come out til much later -coloured tables came in when the laminator got over heated and left streaks on the chart and some one found it and thought it was meant to be like that- crazy i know but stranger things have happened !

 

[scubadada]

And what did the 1970 (or whatever year they were) table say?

The no deco time was 10 min for 130 and 140 feet. It was 5 min below that to 190 feet. We were told not to dive below 130 feet.

 

[captain]

I was certified by the YMCA in 1970 also. The only tables in use at that time was the US Navy tables. I think PADI was the first agency to have its own table. Not sure when probably late 70’s early 80’s.

 

[100days-a-year]