PADI's dive depth standards - Vague?

[HowardE]

I really hope are kidding!

Dave

I'm not kidding.

 

[CompuDude]

It's my understanding that the "recreational depth limit" of 130' is determined by the probability of nitrogen narcosis, not oxygen toxicity. ??

kari

No, narcosis can kick in as shallow as 80', IIRC, although it's less noticeable and more manageable at that depth.

I'm going to cut and paste, so please forgive me, copyright police:

The 130 foot limit is an arbitrary depth originally adopted by the U.S. Navy because it gave navy divers about 10 minutes of bottom 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. As with many diving issues in the early days of scuba (e.g., the 'no decompression' limits), the Navy standard was also adopted by the recreational training agencies.

Some experienced recreational divers do go deeper than 130 feet, and yet still stay within no decompression limits. However, since the risks of the bends, running out of air, and nitrogen narcosis increase as you go deeper, the training agencies feel that some arbitrary limit must be set and have stayed with 130 feet. Thus, although one can dive deeper and stay within no decompression limits, diving deeper than 130 feet a) is not taught by the recreational training agencies, and b) must be undertaken with great care and an understanding of the increased risks.

 

[letterboy]

I really hope are kidding!

Dave

Why? :huh:

He could have died, I thought it was dangerous. . .

Oh and If I am not mistaken he does dive with split fins. . .

 

[Thalassamania]

What's the difference between a Scuba Diver, (limited to 40') and an OW Diver? *scratching my head*

"Scuba Diver" was also an old PADI course that did not require openwater dives. OW Diver was introduced later.

 

[HowardE]

Oh and If I am not mistaken he does dive with split fins. . .

only on Mondays , Thursdays, and Saturdays.

 

[Thalassamania]

Nope...It is the "suggested" maximum depth. The premise is based on a diver at 132 feet is under a ppO2 of 1.4 ata O2. At this depth it isn't "impossible" to suffer an ox tox hit. It isn't likely but based on Dalton's Law you are breathing the equivalent of 100% O2 at the surface. Is it likely you will suffer an ox tox hit at 132'...no...but again, it isn't impossible and that's why PADI "suggests" 130. Above 132' you can't suffer an ox tox hit on air. Many divers have pushed it to 1.6...218'...and beyond and not suffered an oxygen toxicity hit...but theses guys are not recreational divers either.

No, while that's convenient, the 130 limit comes from the depth at which the US Navy made an operational shift from scuba to surface supplied air. ppO₂ never entered the discussion.

It's my understanding that the "recreational depth limit" of 130' is determined by the probability of nitrogen narcosis, not oxygen toxicity. ??

kari

No

The 130 foot limit is an arbitrary depth originally adopted by the U.S. Navy because it gave navy divers about 10 minutes of bottom 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. As with many diving issues in the early days of scuba (e.g., the 'no decompression' limits), the Navy standard was also adopted by the recreational training agencies.

Correct, though I don't know about the 10 minute thing.

 

[Karibelle]

No, narcosis can kick in as shallow as 80', IIRC, although it's less noticeable and more manageable at that depth.

I'm going to cut and paste, so please forgive me, copyright police:

The 130 foot limit is an arbitrary depth originally adopted by the U.S. Navy because it gave navy divers about 10 minutes of bottom 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. As with many diving issues in the early days of scuba (e.g., the 'no decompression' limits), the Navy standard was also adopted by the recreational training agencies.

Some experienced recreational divers do go deeper than 130 feet, and yet still stay within no decompression limits. However, since the risks of the bends, running out of air, and nitrogen narcosis increase as you go deeper, the training agencies feel that some arbitrary limit must be set and have stayed with 130 feet. Thus, although one can dive deeper and stay within no decompression limits, diving deeper than 130 feet a) is not taught by the recreational training agencies, and b) must be undertaken with great care and an understanding of the increased risks.

With my own copyright apologies, this is from the Encyclopedia of Recreational Diving:

"The problem with narcosis, then, isn’t the
narcosis, but the impairment it can cause by
delaying responses to problems, affecting
decisions related to safety and interfering
with motor skills. It is narcosis (along with
extremely short no stop limits) that puts the
recreational depth limit for air/enriched air
diving at 40 metres/130 feet."

So, I say "no" to your "no."
kari

 

[letterboy]

only on Mondays , Thursdays, and Saturdays.

Exactly. . . Was there anything wrong with my statement?

 

[CompuDude]

With my own copyright apologies, this is from the Encyclopedia of Recreational Diving:

"The problem with narcosis, then, isn’t the
narcosis, but the impairment it can cause by
delaying responses to problems, affecting
decisions related to safety and interfering
with motor skills. It is narcosis (along with
extremely short no stop limits) that puts the
recreational depth limit for air/enriched air
diving at 40 metres/130 feet."

So, I say "no" to your "no."
kari

So... you're saying narcosis does not begin until 130 feet?

While I'm sure narcosis avoidance played a factor in wanting to set a depth limit of some sort, the 130' rule was indeed adopted from Navy standards... not a number at which narcosis is suddenly a concern.

 

[Teamcasa]

Here is whatwe've learned so far.

PADI’s Recreational Depth limit is 130’ (40m)
This applies to all certification levels except the Scuba Diver cert.
PADI only RECOMMENDS max depths for OW and AOW divers based on training and/or experience levels.
Standards applied by Individual Dive Master(s) and some Dive Operations are generally:
PADI OW – Depth limit 60’ (18m)
PADI AOW - Depth limit 100’ (30m)
A review of your logs or lack of, may influence some operations one way or the other.
Some Individual Dive Master(s) and Dive Operations hold to hard line limits, with no regard to the divers actual experience levels.
So far, only the Maldives employ actual SCUBA police and are instructed to shoot to kill and diver exceeding the depth limits set forth by their Government.
Split fins are funny looking.
Narcosis can happen at any depth below 10’
You will die if you dive below 130’
Wait – I’m off track…

My advice is to call and speak to the dive op about their self imposed, officious rules before you plop down any cash for a dive with them. If they change the requirements after payment, ask the nearest deckhand if he is familiar with the boat’s “man overboard” procedures. If he is, tell him to get ready, he’ll know why in a second.

Dave