The depth shall be 60, 60 shall the depth be, 61 is right out unless your AOW certified????

[dmaziuk]

Note that if the diver is breathing hard, and exhales completely, there is still 1.0 to 1.5 liters of air in the lungs...

I do remember that chart, thanks, but... google... google... OK, this: Muscle tissue has two sources of oxygen 1 oxygen that - PHYSIOLOGY - 1001 -- scroll down to "Oxygen Debt" slide on p. 14. This is the kind of numbers I remember from back when I was a kid athlete turning geek. These guys claim 0.5l O2 in the lungs which would translate to about 2.5l of air @ 1atm, so they must assume a full "regular" breath.

These guys: <a href="oxygen store">oxygen store</a> don't count the lungs and give slightly lower numbers for blood and tissues, but not that much lower.

Yes, at depth there is of course pressurized gas in the lungs and in the cylinder -- though if I had to CESA from depth I'd be tempted to ditch the cylinder and BCD so I could swim faster. I'd blow the ascent rate (you most likely would anyway), but as @Killerflyingbugs says: DCS is more survivable than death.

 

[2airishuman]

The only diving depth rules that can be enforced by an agency are the ones for the training dives, and an instructor can be punished for violating those limits. No agency has the power to enforce any limits outside of the training environment. A government can make such rules for its jurisdiction. A dive operation can make such rules for its divers. A diving agency, though, has no such authority.

Real world is that dive charters, insurers, and people who control shore access all check C-cards. Some insist that you dive within the "limits of your training" or the "limits of your certification." I've run into depth limits based on agency and OW/AOW certification, most recently at the dive concession at Pennekamp State Park.

Its really easier to just get the AOW card and be rid of the hassle of who interprets what which way.

A necessary but not sufficient step

Wait, what? you need a deep diver card to be certified to go deeper than 100 feet?

The maximum depth for the deep dive that is a part of the AOW training is 100 feet, and PADI now considers AOW training to be sufficient only to that depth. Other agencies have different limits, I believe.

.
Progressive exposure and practice at increasing depths is probably more important than plastic cards.

If you are a new diver don't overestimate the value of cards nor disregard the importance of a slow progression toward deeper sites.

+1

 

[dumpsterDiver]

I had a buddy who I dove with for years, often on a shipwreck in 180 ft. One day he asked me about getting certified because he wanted to go to the Caymans or something on vacation and dive with his wife.

I contacted a PADI instructor and she came out (on his boat), gave him a quiz at the dock, then he and I did our normal 180 ft wreck and then for the second and third drops she dove with him in 60 feet .. and he got his OW card. LOL.. i had no idea he wasn't certified - the topic never came up - ever -

He said he taught himself - first with snorkeling and then with scuba and a slow- self taught progression in depth from 30 ft to the deeper wreck we used to do. It is surprising he didn't kill himself along the way. he did say he read the book and started taking a pony on every dive after a bad OOA incident he had in 90 feet.

 

[John C. Ratliff]

I do remember that chart, thanks, but... google... google... OK, this: Muscle tissue has two sources of oxygen 1 oxygen that - PHYSIOLOGY - 1001 -- scroll down to "Oxygen Debt" slide on p. 14. This is the kind of numbers I remember from back when I was a kid athlete turning geek. These guys claim 0.5l O2 in the lungs which would translate to about 2.5l of air @ 1atm, so they must assume a full "regular" breath.

These guys: <a href="oxygen store">oxygen store</a> don't count the lungs and give slightly lower numbers for blood and tissues, but not that much lower.

Yes, at depth there is of course pressurized gas in the lungs and in the cylinder -- though if I had to CESA from depth I'd be tempted to ditch the cylinder and BCD so I could swim faster. I'd blow the ascent rate (you most likely would anyway), but as @Killerflyingbugs says: DCS is more survivable than death.

dmaziuk,

First, I followed your link, and could not confirm where the information came from. It is not too coherently presented. A CESA can be problematical if you are not well trained in doing it. Remember, CESA means "Controlled Emergency Swimming Ascent." If you ditch your scuba and BCD, and swim fast to the surface, you risk AGE (to throw another acronym in there--Arterial Gas Embolism), and that can be very quickly fatal. I really don't like the on-line PowerPoint-style "information," as it is incomplete.

Here is what the current U.S. Navy Diving Manual, Revision 6, 15 April, 2008, states about prevention of AGE:

• A diver must exhale continuously while making an emergency ascent. The rate of exhalation must match the rate of ascent. For a free ascent, where the diver uses natural buoyancy to be carried toward the surface, the rate of exhalation must be great enough to prevent embolism, but not so great that positive buoyancy is lost. In a uncontrolled or buoyant ascent, where a life preserver, dry suit or buoyancy compensator assists the diver, the rate of ascent may far exceed that of a free ascent. The exhalation must begin before the ascent and must be a strong, steady, and forceful. It is difficult for an untrained diver to execute an emergency ascent properly. It is also often dangerous to train a diver in the proper technique. (U.S. Navy Diving Manual, 3-8.1.1)

Now, if you want a better understanding of the respiratory system, and breathing on the body and at the cellular level, please read Chapter 3 in its entirety of the U.S. Navy Diving Manual. Note that this manual is available in full at the above link. You don't have to pay for it, like you do for the NOAA Diving Manual (another excellent resource), and other publications, including the one you linked to. Note that this manual does not say how many liters of oxygen are in the body, as physiologists don't look at it this way. They look at the saturation of oxygen in the hemoglobin. Also, it doesn't matter much how much oxygen is in the body, it is the amount that is in circulation to the brain that matters most. Here's an explanation of hypoxia:

3-5.1

Oxygen Deficiency (Hypoxia). Hypoxia, is an abnormal de ciency of oxygen in the arterial blood. Severe hypoxia will impede the normal function of cells and eventually kill them. The brain is the most vulnerable organ in the body to the effects of hypoxia.

The partial pressure of oxygen (ppO2) determines whether the amount of oxygen in a breathing medium is adequate. Air contains approximately 21 percent oxygen and provides an ample ppO2 of about 0.21 ata at the surface. A drop in ppO2 below 0.16 ata causes the onset of hypoxic symptoms. Most individuals become hypoxic to the point of helplessness at a ppO2 of 0.11 ata and unconscious at a ppO2 of 0.10 ata. Below this level, permanent brain damage and eventually death will occur. In diving, a lower percentage of oxygen will suf ce as long as the total pressure is suf cient to maintain an adequate ppO2. For example, 5 percent oxygen gives a ppO2 of 0.20 ata for a diver at 100 fsw. On ascent, however, the diver would rapidly experience hypoxia if the oxygen percentage were not increased.

Now, let me explain how I have practiced a Controlled Emergency Swimming Ascent (CESA) in a pool. I have access to a pool which is a rectangle, 25 yards by 50 meters long, and with a diving area for platform diving that is 18 feet deep. I have done a doff and don exercise in the corner of the deep end, and swam diagonally across the deep end of the pool to the surface on the far end. Since the pool is 25 yards wide, and I swam diagonally across the deep end, I estimate that I actually swam about 90 or so feet to the surface (although only ascending 18 feet in real depth). I started out on an exhale too, so my lungs were not full. I was able to exhale the entire swim to the surface, and got some advantage from the ascent during that time. I did not "hurry" the swim either, but simply swam across the pool and up to the surface.

Now, I've beed diving since 1959, and am pretty comfortable in the water (ex-NAUI instructor, U.S. Navy School for Underwater Swimmers, Pararescue parascuba training, and my first scuba course, Los Angeles County after having dived for three years without formal training). I don't necessarily recommend this exercise for anyone else, but write about it so you'll know it is a fairly easy exercise to do, and would be easier from an actual depth of 90 feet due to the increased amount of air available.

By the way, I then swam back down to the scuba unit I had left on the bottom, and across the pool, to don the unit again without problems, again simulating swimming to a depth of 90 feet to put the scuba back on (doff and don exercise).

SeaRat

 

[AdivingBel]

I've run into depth limits based on agency and OW/AOW certification, most recently at the dive concession at Pennekamp State Park

Can you be more specific about what they told you? I haven't dived with that particular dive op, but I have dived with several other Upper Keys ops. If you walk in off the street (i.e. they don't know you), they may require AOW or some other proof you have completed similar dives (recently logged dives; a diver they know vouches for you; a checkout dive) prior to taking you out to one of the "deep" wrecks. If you can't provide any of those, they will still take you out if you hire a guide. If we're talking "real world," I don't think it really has anything to do with conforming to an agency depth recommendation. I would still advise getting an AOW or equivalent if you're going to be dive traveling if for no other reason than to make yourself "dive friendly" for the dive op and to make your travel/vacation as hassle free as possible. I personally like hassle free whenever possible.

 

[jonhall]

The answer is in your PADI OW manual. Page 7, right column, down at the bottom of the page. "As a PADI Open Water Diver, you will be trained to a maximum depth of 18 meters/60 feet (or the actual depth you reached if shallower)." Note the 60 feet is a maximum. It doesn't mean you are "automatically" certified to 60 feet if your checkout dives were shallower than 60 feet.

In my PADI OW manual, copyright 1990, 1994, it states for the first time on page 199. "....As an Open Water Diver, limit your dives to a maximum depth of 60 feet. Divers with greater training and experience should generally limit themselves to a maximum depth of 100 feet." Goes on to state that divers with Deep Diver training and a reasonable objective may dive as deep as 130 feet and that all dives should be planned as NDL with no dive exceeding the depth limitation for rec scuba, 130 feet.

Later on page 257, in a summary it reads, "Limit your depth to 60 feet or less. Remember that 60 feet is the recommended limit for new divers."

The maximum depth for the deep dive that is a part of the AOW training is 100 feet, and PADI now considers AOW training to be sufficient only to that depth. Other agencies have different limits, I believe.

My new Adventures in Diving manual, copyright 2010, reads, "As a new Open Water Diver, 18m/60ft marks the depth limit to which your qualified to dive." and "The Deep Adventure Dive.......by qualifying you to dive as deep as 30 m/100 ft, in conditions as good or better than those in which you have training and experience." Also mentioned, of coure, is that the maximum rec limit is 130 ft.

The difference through the years seems have gone from "a recommended limit" to a "depth limit to which you're qualified." Balderdash!!!! I've been wanting to use that word!

I would still advise getting an AOW or equivalent if you're going to be dive traveling if for no other reason than to make yourself "dive friendly" for the dive op and to make your travel/vacation as hassle free as possible. I personally like hassle free whenever possible.

Having had a span of 18 years between OW and AOW (even though my old OW manual reads, "You'll want to enroll immediately after finishing your Open Water Diver course,") this is exactly the reason I got AOW. Granted, I thought it was interesting to make note of color change at depth, but other than that, I can't say I learned anything new. Oh, well. Now, to see if the c-card really makes a difference.

 

[Bob DBF]

I had a buddy who I dove with for years, often on a shipwreck in 180 ft. One day he asked me about getting certified because he wanted to go to the Caymans or something on vacation and dive with his wife.

I dove for 17 years before I got a c-card. I was fine diving locally, but it was getting more dificult getting fills out of area. More recently, I picked up AOW and Deep to avoid a "you can't dive because you don' have a card", and a bet with my kid.

He said he taught himself - first with snorkeling and then with scuba and a slow- self taught progression in depth from 30 ft to the deeper wreck we used to do. It is surprising he didn't kill himself along the way. he did say he read the book and started taking a pony on every dive after a bad OOA incident he had in 90 feet.

I snorkeled and freedive do as a kid and learned SCUBA diving from "The New Science of Skin And SCUBA Diving", which was the basis for the OW training given by the agencies later when they started, is at least as/or more complete than the training given now. It, the Navy dive manual, and a couple of mentors had me doing what is now called technical dives, without incident, before I was OW certified. I now use a pony on deep dives because I am not as young as I used to be, rather than any particular incident.

As for checkout dives, everybody has to do what they have to do, I could get indignant but it wouldn't get me in the water on a better dive faster or build any good will with the dive op so why waste the energy. I've already had more dives than I ever expected, so any dive is a plus for me.


Bob

 

[oldschoolto]

I had a buddy who I dove with for years, often on a shipwreck in 180 ft. One day he asked me about getting certified because he wanted to go to the Caymans or something on vacation and dive with his wife.

I contacted a PADI instructor and she came out (on his boat), gave him a quiz at the dock, then he and I did our normal 180 ft wreck and then for the second and third drops she dove with him in 60 feet .. and he got his OW card. LOL.. i had no idea he wasn't certified - the topic never came up - ever -

He said he taught himself - first with snorkeling and then with scuba and a slow- self taught progression in depth from 30 ft to the deeper wreck we used to do. It is surprising he didn't kill himself along the way. he did say he read the book and started taking a pony on every dive after a bad OOA incident he had in 90 feet.

That sounds the same as my story... Started scuba at 12 and read the book " The art of skin and scuba diving" if I remember right... My buddy did my C-card ( AOW ) like 10 yrs ago... So I could get tanks filled..

Jim

 

[NAM001]

In my PADI OW manual, copyright 1990, 1994, it states for the first time on page 199. "....As an Open Water Diver, limit your dives to a maximum depth of 60 feet. Divers with greater training and experience should generally limit themselves to a maximum depth of 100 feet." Goes on to state that divers with Deep Diver training and a reasonable objective may dive as deep as 130 feet and that all dives should be planned as NDL with no dive exceeding the depth limitation for rec scuba, 130 feet.

Later on page 257, in a summary it reads, "Limit your depth to 60 feet or less. Remember that 60 feet is the recommended limit for new divers."



My new Adventures in Diving manual, copyright 2010, reads, "As a new Open Water Diver, 18m/60ft marks the depth limit to which your qualified to dive." and "The Deep Adventure Dive.......by qualifying you to dive as deep as 30 m/100 ft, in conditions as good or better than those in which you have training and experience." Also mentioned, of course, is that the maximum rec limit is 130 ft.

The difference through the years seems have gone from "a recommended limit" to a "depth limit to which you're qualified." Balderdash!!!! I've been wanting to use that word!



Having had a span of 18 years between OW and AOW (even though my old OW manual reads, "You'll want to enroll immediately after finishing your Open Water Diver course,") this is exactly the reason I got AOW. Granted, I thought it was interesting to make note of color change at depth, but other than that, I can't say I learned anything new. Oh, well. Now, to see if the c-card really makes a difference.

My wife had at the time not dove deeper than 30 ft. I took her to vortex FLA to the cave entrance. she nearly crapped when she saw she was at 60' and when we surfaced she was amazed as to why she had so little air. had she ignored her spg and was at 100 ft diving like she was at 30 she would have gone OOA. Its the little things that, to most of us, make no difference but to new divers are new life preserving discoveries. So many like to cling to the REC diving limit and will not consider that with the courses OW AOW DEEP you are only partially certified as a rec diver with only OW.

 

[spoolin01]

Here's how I summarized my 1994 OW PADI manual in a similar thread from last year. Neither the training or manual at that time was oriented towards circumscribing depth per se within the rec diving zone:

"I was PADI OW certified in 1995, using the 1994 manual. I don't recall much emphasis if any being made of a 60 ft limit, but have stronger recollection of 120-130ft being stressed. Maybe I was enthralled by the instructor's litany of derring-do anecdotes and missed it.

I just thumbed through the manual and the 60 ft business is not mentioned until 200 pages in, followed by extensive discussion of dive tables and the importance of the 100 ft and 130 ft limits in the PADI perspective on recreational diving. The 60 ft limit is at one point described as applying to a "novice", and is restated again in the last few pages as the recommended limit for a new diver. In the front of the book during description of certification and its benefits, no mention of depth as a feature of OW certification is made, aside from inclusion by inference in being qualified to dive within NDL. In particular, you are qualified to "engage in recreational open water diving without... supervision...", which is later defined as 100ft.

So at least back then, it seems the PADI perspective was that OW certification made you good for a *minimum* of 60ft, and that with additional training and experience, you were limited only by NDL and PADI's assignment of the 100ft rec limit. Is it presented differently nowadays?"