History of 18m depth limit?

[tursiops]

This is my personal idea and is open to discussion.
If you consider a standard RMV and you calculate the amount of air you need to do a square dive to a depth of 18 meters + security stop + reserve, you will have the amount of air in a standard 80 cf cylinder.
Diving to a shallower depth you will be limited by the amount of air in the cilinder.
Diving to a deeper depth you will be limited by the NDL.
So, as an OW diver without deep diving training nor experience, it's ok to limit your depth to 18 meters.

I suspect this is the underlying reason for the 60ft recommendation for new divers. In a square profile, tables-based world, you only have to watch your SPG. Now, with computers and Nitrox, it is not so clear....

 

[-Moe]

More courses = More money"

That's absolutely my take on this as well.

 

[tursiops]

That's absolutely my take on this as well.

LOL. Another bleak view.

An alternative view is that surveys of new and prospective divers showed an increasing unwillingness to spend the time and money for a long involved class that had "everyting" in it. So, in response to customer pressure snd decreasing attention spans, training became more modularized.

 

[Eric Sedletzky]

LOL. Another bleak view.

An alternative view is that surveys of new and prospective divers showed an increasing unwillingness to spend the time and money for a long involved class that had "everyting" in it. So, in response to customer pressure snd decreasing attention spans, training became more modularized.

Of course they’re unwilling to spend the time and money (mostly the time). They’re used to fast and cheap, everything now, the customer is always right, who needs that much training to do something that easy? It looks fun, let’s try it, how much?!?!
Minimizing and shortening training just to please short attention spans might mean more bucks to the agency in the long run (maybe), but it also means very low skill levels. As short as some of these courses are nowdays there’s no way they can fit in everything they should know plus the practice to be able to scuba dive safely. The gear is great these days, better and easier to use than many years ago, but they (the dive industry) are counting on it as a crutch. As long as nothing goes wrong and everyone’s having fun it’s great, but as soon as someone has a problem and things go awry is when the lack of training and experience can become a serious issue. They have weighed out the statistics and came to the conclusion that they can drastically reduce the class time and still be OK and within a tolerable safety limit...as long as nothing goes wrong.

These abbreviated modular step courses don’t do anybody any favors IMO. But then we wouldn’t want to kill peoples’ fun on vacation now would we? Or god forbid take too much of their one or two weeks that they’ll be there!
And what makes you think they will actually continue with courses after open water? They already got to blow bubbles and look at pretty fish, why would they need to go on? Some will but most won’t.

 

[broncobowsher]

Where is that thread about standards being dumbed down? That should have been plugged into this thread by now.

Typical open water customer (that doesn't live near any diving meca),
Going on a vacation to (insert some warm water destination), the vacation of a lifetime type of thing, bucket list. Will they ever want to dive some cold dark pond when they are done? No. OK, what's the quickest way to get someone on there vacation, you have the current standards. Warped just enough to also be a primer if they want to stay in the sport.

The next step down, the vacation diver class. Just enough training to dive supervised in a group in clear water. Expires 1 year after signing up. Any bets on this being the next dumbed down level of PADI?

 

[Bob DBF]

So in the mid 90's 140' was still acceptable for the Open Water class. Falls in line with my NAUI training in '91.

It was not because it was acceptable, the 130' recreational limit was already established by then, it was needed to give a pressure group and calculate RNT if you inadverdently exceeded 130'. Without that there is no way to properly calculate the next dive and you are done for the day.

Because few use or teach tables in the computer age, it is becoming unnessary to know.


Bob

 

[boulderjohn]

Where is that thread about standards being dumbed down?

I am taking a break from ScubaBoard, and I hoped someone would correct all the misinformation in this thread. I will try to do it now.

• In the earliest days of recreational diving, diving was primarily guided by the US Navy tables. Other tables simply followed those tables, and some still do today (including NAUI and SSI).
• Those tables were not designed for recreational diving only, and they included decompression schedules. They had to follow a specific theoretical compartment to guide repetitive diving, and they chose the 120 minute compartment. That would be just fine for people doing one decompression dive a day, but it was very inconvenient for people doing shallower, NDL dives, because it led to unnecessarily long surface intervals.
• PADI's research leading to the RDP told it that by shortening the NDL for first dives by a few minutes and by limiting divers to a maximum of 130 feet with no decompression stops, they could safely use a shorter theoretical compartment (60 minutes) and dramatically cut down on surface intervals. This led to a major change in recreational diving, bringing about the typical recreational 2-tank dive schedule we know today. That table was meant to guide all recreational diving, not just OW classes. The PADI RDP has not changed at all since it was implemented.
• Training standards for the OW class limited student divers to 60 feet. That is, however, strictly a limit for the OW training class, not for divers out on their own. Once divers are out on their own, they are free to follow the limits of whatever tables or computer they are using. That has been true for decades and has not changed.
• All agencies tell students to limit their post certification dives to what they have experienced at first and then extend limits as their training and experience grows. Students are recommended to begin with the 60 foot limit from their class and then extend deeper as their skills grow. That has been true for decades and has not changed.
• Quite a few years ago PADI replaced buddy breathing in the OW curriculum with air sharing with a buddy's alternate air source. It later made two versions of the course--tables or computers. Other than that, the only changes in the OW course are the more than 15 new requirements PADI added to the OW curriculum a number of years ago. The OW course is thus more robust now than it was decades ago. Despite that, people like to claim that the OW curriculum is constantly being dumbed down. I don't know why people like to do that, but that has been true for decades and has not changed.

 

[tursiops]

I am taking a break from ScubaBoard, and I hoped someone would correct all the misinformation in this thread. I will try to do it now.

• In the earliest days of recreational diving, diving was primarily guided by the US Navy tables. Other tables simply followed those tables, and some still do today (including NAUI and SSI).
• Those tables were not designed for recreational diving only, and they included decompression schedules. They had to follow a specific theoretical compartment do guide repetitive diving, and they chose the 120 minute compartment. That would be just fine for people doing one decompression dive a day, but it was very inconvenient for people doing shallower, NDL dives, because it led to unnecessarily long surface intervals.
• PADI's research leading to the RDP told it that by shortening the NDL for first dives by a few minutes and by limiting divers to a maximum of 130 feet with no decompression stops, they could safely use a shorter theoretical compartment (60 minutes) and dramatically cut down on surface intervals. This led to a major change in recreational diving, bringing about the typical recreational 2-tank dive schedule we know today. That table was meant to guide all recreational diving, not just OW classes. The PADI RDP has not changed at all since it was implemented.
• Training standards for the OW class limited student divers to 60 feet. That is, however, strictly a limit for the OW training class, not for divers out on their own. Once divers are out on their own, they are free to follow the limits of whatever tables or computer they are using. That has been true for decades and has not changed.
• All agencies tell students to limit their post certification dives to what they have experienced at first and then extend limits as their training and experience grows. Students are recommended to begin with the 60 foot limit from their class and then extend deeper as their skills grow. That has been true for decades and has not changed.
• Quite a few years ago PADI replaced buddy breathing in the OW curriculum with air sharing with a buddy's alternate air source. It later made two versions of the course--tables or computers. Other than that, the only changes in the OW course are the more than 15 new requirements PADI added to the OW curriculum a number of years ago. The OW course is thus more robust now than it was decades ago. Despite that, people like to claim that the OW curriculum is constantly being dumbed down. I don't know why people like to do that, but that has been true for decades and has not changed.

Thank you!
SB'ers will know that I get a bit anal on people incorrectly stating or interpreting training standards, especially those from PADI. I have nothing to disagree with in this post from BoulderJohn.

 

[Sam Miller III]

too historical -- no interest

 

[yle]

This is my personal idea and is open to discussion.
If you consider a standard RMV and you calculate the amount of air you need to do a square dive to a depth of 18 meters + security stop + reserve, you will have the amount of air in a standard 80 cf cylinder.
Diving to a shallower depth you will be limited by the amount of air in the cilinder.
Diving to a deeper depth you will be limited by the NDL.

This is the explanation I give to my OW students, while I teach them about the tables. Dives shallower than 60 feet will tend to be limited by air, dives deeper than 60 feet will tend to be limited by NDL. The OW course tends to focus on "monitor your air, do not run out of air", while the AOW course places a greater emphasis on dive planning.