History of 18m depth limit?

[tursiops]

In 1993, in PADI's "Scuba Tune-Up," PADI's words were:

"130 feet/40 metres is the maximum depth limit for recreational divers. However, you should limit yourself to a maximum depth that reflects your training and experience. Open water divers should limit themselves to a maximum depth of 60 feet/18 metres. Divers with greater training and experience should limit themselves to 100 feet/30 metres. if you have special Deep Diver training you may venture as deep as 130 feet/40 metres."​

In 2009, the revised "Scuba Tune-Up" (rev. 7/11) said:

"The absolute maximum depth for recreational diving is 40 metres/130 feet. This limit is based on the short no stop limit at that depth, the fact that you use air faster, equipment limitations, and other factors. It applies to divers with suitable experience/training, and to conditions that make deep diving reasonable. For beginning Open Water Divers, the recommended depth limit is 18 metres/60 feet, with 30 metres/100 feet the generally recommended limit. Remember that when applying limits, to consider your experience with the depth, the environment, the conditions,your buddy's limits and anything else that may call for a shallower maximum depth."​

 

[tursiops]

I have five versions of the PADI Open Water Diver Manual:

Version 1.0, copyright 1990 and 1994.​

Version 2.1, copyright 1999.​

Version 2.10 (rev 11/08), copyright 2008.​

Version 3.0 (rev 08/13), copyright 2013.​

The eLearning version of the manual, version as of today.​

In Versions 1 and 2, there is a figure that looks like this:

DEPTH LIMITS​

• 18 m/60 ft Novice
• 30m/100 ft Recommended
• 40m/130 ft Absolute

In Version 3 that changed to the same figure as in the current eLearning, below.

In the eLearning (current) version of the manual, it says this regarding limits:

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I interpret the shift over the years to mean less emphasis on specific limits for each training level, and more emphasis on a strong recommendation of 18m/60 ft max for new OW divers, but from there to 130 ft it is up to the diver and any training and/or experience they get.