Dive planning/ Air consumption question

[TSandM]

As I said, I attended a gas management seminar given by NW Grateful Diver. Then I took Fundies, and the same information was there.

BTW, I have done the PADI sequence through AOW, the Deep specialty, and Rescue, and these topics were never addressed.

 

[TxHockeyGuy]

NAUI AOW goes over this, or at least they did in my class. I haven't done the dives yet but if I get the same instructor I had for the class he did state we would be determing our SAC rate and would utilize that information for planning our deep dive.

 

[DA Aquamaster]

I am curious where everyone learned of this sort of information? I do not remember hearing anyhting about gas management in any of my PADI courses. I only remember coming accross this in the DSAT (still PADI) TecRec course. I am working on becoming an Instructor now so I have run the gamut with PADI courses, perhaps I have just jumbled up all of the courses at this point and its been years since OW and AOW. But DM was just last year.

So I guess my question is when/where did you learn gas management?

We covered it in detail in my 1984 vintage PADI OW course and then expanded on it in my 1985 vintage PADI AOW course with things like deco procedures. Of course that was back when you had to know math to get certified as you knew and understood all of the relvent gas laws petaining to scuba diving.

Somewhere between then and now (a lot closer to then than now) certification agencies dummied down OW and AOW courses to make it easier to market scuba certifications to the teeming masses in order to create a large market for scuba gear and totally useless specialty courses.

It's pretty sad I think as it changed the focus from creating divers who were fully capable and self sufficent in terms of things like dive planning, etc, to one of creating dependent divoers who have to rely on dive masters for planning and guidance.

It's almost criminal.

 

[Scuba_Steve]

It's almost criminal.

I'd leave out the "almost" myself.

I'm waiting for a high-dollar boy to up and die after OW training and have his zillions sue the @$$ off of the big dollar agencies for gross negligence of diver training standards.

That's a can of worms worth opening IMO.

But then I think this is pretty important stuff. YMMV.

 

[H2Andy]

the thing is, this stuff is not rocket science

anyone with a sixth grade math level (or me with a calculator) can figure
this stuff out

i think the agencies just don't want to increase the time it takes to get
people in and out.

in that respect, it is criminal

 

[MXGratefulDiver]

I am curious where everyone learned of this sort of information? I do not remember hearing anyhting about gas management in any of my PADI courses. I only remember coming accross this in the DSAT (still PADI) TecRec course. I am working on becoming an Instructor now so I have run the gamut with PADI courses, perhaps I have just jumbled up all of the courses at this point and its been years since OW and AOW. But DM was just last year.

So I guess my question is when/where did you learn gas management?

I got some (the most basic) info in my YMCA AOW class ... we did SAC calculations and discussed turnaround pressure.

I got most of what I know about gas management from mentors ... experienced divers who cared enough to want to show me how it was done.

I have not seen it presented (in a substantive manner that's usable to the recreational diver) in any NAUI student materials ... that's why I wrote my own.

... Bob (Grateful Diver)

 

[scububa]

Forgot to mention that V is the internal volume of the tank. If the world worked on metric units life would be so much easier!

My daughter just attended a math society induction and related this joke the speaker told...

When ask to provide a summary of how the U.S. was doing in educating and converting to the metric system...the reply was, "We're inching along!"

Great thread and referenced material.

My training was SSI and we did timed SAC measurements at depths. We discussed volume and relation to psi readings. I'd say it was enough to get you started thinking. But, certainly not comprehensively employed. In AOW, there were critical dive planning questions from the instructor that made you employ it. He would ask a buddy team what their plan was and help you to see the weak spots. I lead a dive with him as my buddy and when we got back, he pointed out that I hadn't gone over ascent stops (I simply assumed a 15 ft stop and it was deep enough to consider alternates) and that I hadn't specified turn criteria very well.

 

[cerich]

I have not seen it presented (in a substantive manner that's usable to the recreational diver) in any NAUI student materials ... that's why I wrote my own.

... Bob (Grateful Diver)

Hey Bob, it is discussed in a introductory manner on page 105-106 of the Scuba Diver Manual but to my way of thinking it could have lots of more meat to it. Particularly when it is a standard that our Scuba students calculate their SAC, thus how to do so should be in the manual (or at least a get a SAC rate calculator and how to use paragraph). I suspect that is why many instructors (NAUI) break standards by not teaching it when they have the student do the book and DVD at home then jump right to CW and OW.

Send me your notes, I'd love to see them.

Best,

Chris

 

[Doc Intrepid]

You know, I feel dumb asking this, but

...I don't have the slightest idea how much air is in the tanks I've been renting.

... pressure doesn't mean much without knowing volume, sure....

but.....there isn't anything about this in the textbooks.

Check out the section in your textbook on tank markings.

In the case of many manufacturers, amongst all the cryptic markings stamped on the neck of the tank are 'intended' volume of the tank and its rated fill pressure. Ergo, in the case of a PSI 130 at its rated fill pressure you'll have 130 cubic feet of gas in the tank.

The tanks you rent can be underfilled on occasion, and it's certainly feasible to overfill them, but this gives you a place to begin - at least with most tanks you'll be able to rent.

As far as when many diver's begin learning about mathmatical formulas to calculate tank volume, turn times when diver's have different sizes of cylinders, SAC/RMV rates, and other gas fundamentals (Currently...), its often around the "Advanced Nitrox/Extended Range Diving" stages in their development. But it varies.

As DA noted, its considered too arcane for today's entry level divers... which is a pretty sad commentary.[/GEEZERRANT]

 

[IwakuniDiver]

I came across detailed dive planning mathmatics in the US Navy Dive Manual I believe while studying for Master Diver.

I just took the math that I learned from the various laws and applied them where I saw a need, then created my own tools for tracking them.