PADI Deep Diver course- gas management

[crofrog]

SurfGF had not been invented yet when the RDP was developed, but the RDP has mandatory safety stops if you pass 30m or are within 3 pressure groups of your NDL for any depth. See Info - The DSAT Recreational Dive Planner (RDP), 1994

Ok, so to back our way into the original topic of this post.

With RDP procedurally requiring stops on some dives, is there gas planning as part of the course that takes into account the need to make these stops?

Your comments in this thread are moving step by step into the realm of the bizarre. Of course maximum exposure is defined. The biggest problem we are having is working our way through your verbiage, since you seem to be using words in a way only you can understand.

Maybe I am misunderstanding what you are writing, but you seem to be saying that the course should predefine the specific depths and bottom times of each dive rather than have the divers work those out with the instructor.

If you're not defining as part of the course standards Maximum Depth AND Maximum Time at that depth then you are not defining the maximum exposure. I do not think the specifics should be defined per dive, but I think course limits should be in place.

Saying "follow the computer" leaves a lot up to individual computer setup and algorithm selection. Unless you define allowable algorithms and computers.

 

[tursiops]

With RDP procedurally requiring stops on some dives, is there gas planning as part of the course that takes into account the need to make these stops?

If you're not defining as part of the course standards Maximum Depth AND Maximum Time at that depth then you are not defining the maximum exposure. I do not think the specifics should be defined per dive, but I think course limits should be in place.

Saying "follow the computer" leaves a lot up to individual computer setup and algorithm selection. Unless you define allowable algorithms and computers.

You can't a priori state the limits because it depends on the students, the gas, the site, the conditions. All you can say a priori is you can't exceed 130 ft/40m, nor NDL, nor 60 f/min or what your computer's ascent rate is. The students are likely to have different computers; maybe different gases. So you find out what the limiting case is. that is, whose NDL is the shortest, whose ascent rate is the slowest, and that becomes the limit for all in the class. Then you discuss gas usage. Again, the person with the highest SAC becomes the limiting case for the class; if they don't know their SAC (and they should by this class) call it 0.7 cu/ft/min to cover most people. You work out gas usage, with a comfortable reserve (please, let's not dwell on that!), and then maybe have to back off further on the max depth or the max time to meet the gas usage requirements. The point is to have the students learn how to do this, NOT to predesign a perfect dive and have them execute it; they learn nothing from that.
Now, perhap all instructors don't do it that way; all I can say is how it is intended to be done and how I did it as an instructor.

 

[Sebs]

I did my deep diver in Dahab with a Tech Instructor and specifically told him I wanted to do a lot of gas planning because that's what I was interested in. So we did that and I went away feeling like it was the best course I've ever done.

So I would say: Find an instructor who will teach the course how you want it to be taught. Especially with something like Deep you really need to be on top of gas requirements. Who gives a **** if the color red disappears as you go deeper when you're sucking down a tank in 5 minutes.

 

[Leatherboot69]

I had an enjoyable Sunday morning reading this thread from start to finish. It seems - in sum - that agencies (including PADI) have published training standards that are research backed and that allow recreational divers to dive within certain risk tolerances, but that some commenters on the thread do not think that those standards are correct based on several reasons ranging from conjecture and opinion to anecdotal experience to interpretation of subsequent research.

I was taught gas planning at OW, AOW and Deep Spec levels. I’ve found I’ve had relatively limited need until recently to use the calculations for single tank NDL air dives in the <30m range rather than just knowing my turn pressure and reserve, which of course is how millions of dives each year are safely conducted. The main reason I’ve started using them is to prevent skill fade rather than because they have been intrinsically useful on a dive. I would definitely use them for dives in the 30-40m range where risk tolerances are lower because of the increased gas consumption and shorter NDL times, as well as having less experience at those depths and so less instinctive understanding upon which to base decision making.

I’m actually quite confident in PADI standards for NDL recreational diving in circumstances similar to in which I’ve been trained or in which I have developed experience - which is, of course, all I am certified for. There is no incentive whatsoever for PADI to publish training standards or other material that is unsafe.

 

[wetb4igetinthewater]

Well that settles it!

 

[Kris Reynolds]

I teach the PADI Deep Diver course fairly often in Canada. It think it is worth while for many students, especially if they are considering going beyond the course into any more advanced diving.

For many of the students that I teach, it is the first time they have actually use SAC to plan needed gas consumption in advance of a dive. The planning process (which many have long stopped practicing) makes it clear that small things can snowball quickly. Many divers tend to become complacent over the years following Advanced Open Water, and the deep course increases caution and diligence. It also proves to divers that narcosis does in fact affect them, regardless of how they might perceive that it doesn't.

The course is a good indicator for divers that they may or may not be ready or might not actually want to continue to the Tec program.

Lastly, more advanced diving; technical diving in particular has a considerable barrier of ego surrounding it. It can be intimidating, and uninviting for divers who don't have peers already diving to those levels. It can be hard to find a team to progress with. A course like the PADI deep diver course allows them to continue progressing safely with an instructor, and often meet others who want to continue to with them.

Courses of any kind offer more opportunities to keep divers engaged in the sport, and can often expose divers to instructors that may expand and improve upon what they have learned, and that's mostly a good thing.

 

[Capt Jim Wyatt]

Plan and manage gas use, including determining turn pressure, ascent pressure and reserve pressure. Establish no stop and dive time limits.

Gas management. Before beginning the descent, remind divers to check their starting pressure and make a note of their turn pressure. During the dive, check cylinder pressures at irregular intervals to confirm appropriate gas management.

Those sentences were copied/pasted directly from the PADI Deep Diver Instructor guide.

 

[jadairiii]

Plan and manage gas use, including determining turn pressure, ascent pressure and reserve pressure. Establish no stop and dive time limits.

Gas management. Before beginning the descent, remind divers to check their starting pressure and make a note of their turn pressure. During the dive, check cylinder pressures at irregular intervals to confirm appropriate gas management.

Those sentences were copied/pasted directly from the PADI Deep Diver Instructor guide.

Does instructor guide define what "appropriate gas management" is? Is "reserve pressure", the individual diver's reserve or the team's reserve? Or is it, "go to 90', come back up and have 500psi in your tank when you are on the boat"?

That was sort of the question of my original post. But this was helpful, thanks.

 

[tursiops]

Does instructor guide define what "appropriate gas management" is? Is "reserve pressure", the individual diver's reserve or the team's reserve? Or is it, "go to 90', come back up and have 500psi in your tank when you are on the boat"?

I suspect you already have an opinion on what is "appropriate gas management."
So what answer to your question could be given that you would not argue with?

 

[Leatherboot69]

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