Why is 18m set for OW?

[tbone1004]

@boulderjohn 100% agree ones ability to CESA from some depth not equating to them being able to freedive to that depth, but my point was that if you can freedive to some depth, then you should have no issue doing a CESA from that depth. I'm much more liable to try to freedive to 100ft than I am to CESA up from 100ft just to see if I can do it...

 

[Tribal]

I might be wrong but wasn’t the max ascent speed in the past 18m/min?

Maybe thats why some federations use 18m as max depth for beginners?

 

[Flycaster]

Maybe because it's 3 atmosphere's of measurement?

 

[tursiops]

Maybe because it's 0ne atmosphere

?? What is one atmosphere?

 

[Flycaster]

?? What is one atmosphere?

Surface = 1 ata ( atmosphere)
33ft. = 2 ata
66ft. = 3 ata

 

[tursiops]

Surface = 1 ata ( atmosphere)
33ft. = 2 ata
66ft. = 3 ata

Ahh, you fixed your post.
You can ignore my question, which was attempting to clarify what you said.

Now, I do not understand your point. What does 3 ATM have to do with the OP's question?

 

[tbone1004]

I might be wrong but wasn’t the max ascent speed in the past 18m/min?

Maybe thats why some federations use 18m as max depth for beginners?

circling back to a point made earlier, if the ascent rate was chosen by a country working in the metric system it likely would have been 20m/min. 18m/min is 60fpm and is a nice even number in the imperial system

 

[Flycaster]

Ahh, you fixed your post.
You can ignore my question, which was attempting to clarify what you said.

Now, I do not understand your point. What does 3 ATM have to do with the OP's question?

I was suggesting that the agency setting 60ft. as max. depth for OW cert. may have had a standard close to 3 ata for a standard.
A lot of replies in this thread are simply more questions such as my guess.

 

[scrane]

Pay As You Go (Deeper). I believe it is an arbitrary number devised to sell advanced certifications.

 

[Bob DBF]

Pay As You Go (Deeper). I believe it is an arbitrary number devised to sell advanced certifications.

Since I got the same advice when I was a new diver, before PADI was started, I doubt it was their invention. At the time the normal ascent rate was 60 fpm, I had no SPG, and the training insured you handle the ascent without issue. Also, it was pointed out that as you went past 60', an old steel 72 empties fast, putting you in a position that was new to you and best taken slowly and carefully as it was a longer trip to the surface. No BC so you had to swim it up or drop your weight and cork, acceptable but not optimal.

I was not trained by catch phrases, and was given a lot of information and advice about diving in order to make an informed decision on how I would dive.


Bob