I had to stop watching

[tursiops]

I believe the 130 ft/40m NDL was made using doppler research with NASA - taking into account the partial pressure of oxygen and nitrogen.

Dive Risk Factors, Gas Bubble Formation, and Decompression Illness in Recreational SCUBA Diving: Analysis of DAN Europe DSL Data Base interesting article about DCS
Historical Perspectives on Dive Tables and Decompression Models – Divers' Blogs good info and links out to more research and history of development of NDL

You might want to do a bit more research on this. NASA started in 1958, but 130 ft was commonly used long before that. Your article says the Navy limited itself to 130 ft in the 1950s, but they were late to the table.
The 130 ft limit is not really related to NDL, which is a time limit, not a depth limit. the depth limit was more related to gas supply in the tanks commonly used, and especially to narcosis.
PPO2 of air at 130 ft (5 ATA) is 1.05 ATA, which is a non-issue.
PPN2 of air at 130 ft is bout 4 ATM, which is beginning to be serious.
The Diviac blog post has some errors, and is mostly about NDL, not depth limits.
NASA's current research is very much about DCS (ascending too quickly from 1 ATA of 0 ATA) but not to nitrogen narcosis, which is pretty much non-existent at such low pressures. Their O2 toxicity work is more about pulmonary than CNS toxicity, again because of the low pressures but long exposures.

 

[Sam Miller III]

@SapphireMind

my comments apparently were lost in the electronic world ...

I believe the 130 ft/40m NDL was made using doppler research with NASA - taking into account the partial pressure of oxygen and nitrogen.

Dive Risk Factors, Gas Bubble Formation, and Decompression Illness in Recreational SCUBA Diving: Analysis of DAN Europe DSL Data Base interesting article about DCS
Historical Perspectives on Dive Tables and Decompression Models – Divers' Blogs good info and links out to more research and history of development of NDL[
/QUOTE]
``````````````````````````````````````````````````````````````
@SapphireMind
Thank you for your research -- your efforts is appreciated

However American recreational and professional SCUBA diving began long before the establishment of NASA

It is suggested that you research 1940s recreational diving-- where it all began by bunch of sun tanned athletic SoCal youths

Sam Miller,III

 

[Alucard]

Well, I watched that first video and was shaking my head. I mean, people can do whatever they want to, of course, but I really wanted to get some confidence in the water and some skills and some trim before I went too far or deep.

Fact is, I wouldn't want to dive with these people, and I most certainly wouldn't want one of them as a buddy, thanks. 133ft on Nitrox? Descending to 133 feet before everyone had ensured they could descend? Flailing around the whole time with arms, legs, and dangling computers and octos? Kneeling on the bottom while you wait, and stirring up the sand?

The fooling around at depth... meh, if they want to do it, fine, as long as they stay safe.

The good news - in my 130ish dives, I have never seen divers this bad before (and all but one of my dives have been in the Caribbean). I really wouldn't let it stop you from visiting and enjoying the underwater world there.

 

[MaxBottomtime]

“The 130-foot limit is an arbitrary depth originally adopted by the U.S. Navy because it gave Navy divers about 10 minutes of (no-deco) time on compressed air; going any deeper on air made no sense to the Navy because the time available to do useful work was simply too short,” writes Lawrence Martin in Scuba Diving Explained: Questions & Answers on Physiology and Medical Aspect

 

[SapphireMind]

I don't personally have a huge interest in the history of the development of the limit. I was simply trying to answer: "Why does 130 appear to be an universal depth limit in all agencies ?" where a lot of people were shrugging their shoulders.

 

[chrispscott]

I used to think that too, but I recently discovered that isn't true.

In the course of discussing this topic for the purposes of planning our club dive schedule, our safety officer (a CCR instructor) pulled together the depth limits for all sorts of certs with different agencies. Maybe things have changed over the years, but here are the current limits:


View attachment 486248

This chart is incorrect on NAUI AOW. It is taught to a Max depth of 130'. I've attached the current NAUI standard for depth in AOW.

 

[Storker]

I'm not sure that your math works 56m = 1.6 ATM?

1.4, sorry for the typo

 

[doctormike]

This chart is incorrect on NAUI AOW. It is taught to a Max depth of 130'. I've attached the current NAUI standard for depth in AOW. View attachment 486590

Thanks! Will pass this on.