Po2?

Hello newbie question:

My wife and I started diving last year and we were told that a PO2 of 1.6 is perfectly safe.

We went to the Exumas recently and set our dive computers at 1.6 and used EAN 32 at 125 - 130 ft dives.

Is this safe or should we just use air on wall and holes at this depth?

You've done a Nitrox course, right?

1.4 is considered a safe maximum for exertion (general diving), and 1.6 is considered a maximum at rest, such as decompression stops.

Hi narcT, and first I would like to welcome you to the board.

Now for the serious stuff. Are you actually nitrox certified? You should have learned the answers to your questions in your basic nitrox class. Something sounds "fishy" here, what's up dude??

I think "perfectly safe" is rather subjective. Some people have dove well beyond a 1.6 limit all of their life and never taken an ox tox hit, while others have suffered such a hit on a P02 of 1.2 or less.

There are physiological differences between everyone, so all of the tables and charts are stated to be "recommended limits."

I have taken nitrox courses through two different agencies, and both advocate a working PO2 of 1.4 with a contingency of 1.6.

Discussion of this concept should have been an integral part of the course. If you took the course and didnt get this information I would recommend you talk to the instructor and see if there is anything else he left out...

Cave Diver once bubbled...
... see if there is anything else he left out...

Click to expand...

Giving them their money back, maybe?

Hi narcT,

Welcome to the board. I hope my answer doesn't put you off but I hear stories like this from new traveling divers all the time. It makes me want to travel the worlds dive sites thumping instructors and DM's on the head.

NEVER use a gas your not trained to use. Also IMO, new divers have no business at 130 ft. As far as I'm concerned your question proves my point.

MikeFerrara once bubbled...
Also IMO, new divers have no business at 130 ft. As far as I'm concerned your question proves my point.

Click to expand...

This question will probably come out sounding sarcastic, but it is truly not meant to be.

How do you, personally, define your term "new divers"?

1. Length of time since certification?
2. Formal training certification level?
3. Acquired/demonstrated skill and knowledge level?
4. Type of questions asked?

And who, in your opinion, should make the decision of when a diver does "have business" at 130 ft?

The reason I asked is that the tone in your reply puts in my mind visions of you sitting on a throne with a magic wand, clucking selected divers on the head saying "I knight thee NEW DIVER", or "I knight thee ADVANCED DIVER".

But now that I think about it, I guess that is kinda what the LDS guys do when they hand you a new shiney certification card though, huh?

Sorry for the tone in my message, but I just think a thinking diver will know his or her personal limits better than anyone else. And as a general rule of thumb, if you're not sure it's safe, don't do it!

narcT, good for you for questioning things and not just accepting whatever someone tells you. Next time though, I'd respectfully suggest doing it BEFORE the dive...

Maybe it was the time of the morning, but I have to think that this one was way too obvious.

Hook, line, sinker.

And no, it wasn't me.

sealife once bubbled...


This question will probably come out sounding sarcastic, but it is truly not meant to be.

How do you, personally, define your term "new divers"?

1. Length of time since certification?
2. Formal training certification level?
3. Acquired/demonstrated skill and knowledge level?
4. Type of questions asked?

And who, in your opinion, should make the decision of when a diver does "have business" at 130 ft?

The reason I asked is that the tone in your reply puts in my mind visions of you sitting on a throne with a magic wand, clucking selected divers on the head saying "I knight thee NEW DIVER", or "I knight thee ADVANCED DIVER".

But now that I think about it, I guess that is kinda what the LDS guys do when they hand you a new shiney certification card though, huh?

Sorry for the tone in my message, but I just think a thinking diver will know his or her personal limits better than anyone else. And as a general rule of thumb, if you're not sure it's safe, don't do it!

narcT, good for you for questioning things and not just accepting whatever someone tells you. Next time though, I'd respectfully suggest doing it BEFORE the dive...

Click to expand...

IMO, it is the diver of course who needs to decide what type of dive they are ready for. However the decision needs to be made with an honest evaluation of ones skills in relation to the dive plan. IMO, this is often not the case. Too often the new diver just follows the DM (or someone else). What kind of thought do you suppose goes into gas management on dives like this. Most divers I talk to about the "trust me" dives they do reveal that they are in fact almost totally dependant on the dive leader to get them home. There are of course many possible ways of defining what a NEW diver is but in this case I think it is safe to say that a diver who must ask what gas is suitable for a given dive is certainly new. A question I often ask of divers after I hear of their dive is "did they leave the bottom with each diver having enough gas left to get both divers safely to the surface". The answer is almost always that they have no idea. This is a sure sign that they were not prepared for the dive.

The fact is that these dives are usually conducted with no injuries although I hear of many near misses. These divers often come to believe that they are actually qualified to do 100+ dives. They then come to our neck of the woods and get hurt doing a deep dive without supervision.

Your vision of me on a thrown making the decision is not as telling as my vision of watching yet another ambulance run or pulling yet another diver out of the water.

Take a good look at the most recent DAN report. It clearly shows that divers with little recent experience, poorly developed skills, little training and doing deep dives can be a lethal combination. The January issue of "Dive Training" had an article that did a good job of summerising these points. A briefe reveiw of the DAN report is part of every OW class that I teach. I also show the video "A deceptively Easy Way To die" which warns divers to stay out of overhead environment until they have the training and equipment. I show this because of all the newly certified divers who have told me of their dives following DM's into wrecks and coral caves. Of course all these dives were done without following any of the rules we follow to minimize risk in an overhead. I add these things into my class in an attempt to stop divers from blindly following dive leaders.

Sorry DetroitDiver,

I forgot... whatever was I thinking...

<Me, hitting self across knuckles with a wooden ruler>

Bad me! Bad me! Must remember, a self-thinking divier is NOT ALLOWED! Bad me! Bad me! MUST-DIVE-BY-ROTE! MUST-SEEK-APPROVAL-OF-OTHERS! Baaaaad me! Very baaaaad me!

Okay, I'm all better now. I will not think for myself again. Got a book you can recommend that will tell me all I need to know so I will know when I'm Doing It.... Properly (DIP)?

P.S. The last post was NOT a troll. But guess what, this one is...