Does not compute but should I ?

[SeaJay]

No mistake, Mike. That's exactly right.

What they don't teach you in DIR-F is the calculation of decompression times past the NDLs. That comes later in other GUE courses, but not in DIR-F.

'Nuff said.

I have edited my post to be more... Polite. My apologies if I got offensive. This was a really frustrating thread.

 

[wb416]

MikeFerrara once bubbled...

From what you and said I got the impression that DIRF will teach a diver how to calculate their NDL for a multilevel dive on the fly and without a computer.

SeaJay once bubbled...
No mistake, Mike. That's exactly right.

What they don't teach you in DIR-F is the calculation of decompression times past the NDLs. That comes later in other GUE courses, but not in DIR-F.

Calculating NDL's on the fly (multilevel or square profile) wasn't covered in either one of the DIR-F classes I was in, and I had the same instructors that you did. Are you sure it wasn't a side conversation that you had with Andrew or MHK?

 

[SeaJay]

cwb once bubbled...


Calculating NDL's on the fly (multilevel or square profile) wasn't covered in either one of the DIR-F classes I was in, and I had the same instructors that you did. Are you sure it wasn't a side conversation that you had with Andrew or MHK?

No, I specifically remember the event. It was discussed on Friday night, in class.

However, as I'm sure you experienced also, the Friday night "brief" and class is somewhat loosely organized, and there seemed to be quite a bit of discussion and Q+A. Thus, it could have simply "come up" and was not normally a part of DIR-F. Or, the curriculum could have changed to include the procedure. Or, it may have been something that they discussed due to the fact that they had time, or less people, or whatever. Nonetheless, we spent close to an hour going over the procedure and running examples. It kept me up all night Friday night running examples in my head so that I could feel confident with the procedure. I did the same thing with the mathematical weight/trim calculation that they shared that same night.

Whether it's a part of the "normal" curriculum or not, the point is that the information is available to a diver at that point, and from people who know and are qualified and experienced enough to be able to teach the stuff with confidence.

...Which is why I recommend taking the course to people who have questions. The "Rule of 120" is only one tiny tidbit of information available at a DIR-F course, and not even one of the "big morsels" of info.

It boils down to this... And I'm not sure why this thread has gone on so long and continues to be such a huge ordeal... If you want to know what these DIR guys are doing, then go find out. If you want to know what DIR is all about, then go take the course. If you want to argue DIR, feel free, but equip yourself with the information as we've gotten it. If you want to know, because all of this sounds so darn interesting, then we know where you're coming from... We felt the same way... And the only way to "get it" is to take the course. Why does DIR recommend "no computers?" Take the course. What is the "Rule of 120?" Take the course. Why a bp/wings? Take the course. A halfway point to answering these questions would be buying the book and reading it. If you're like me and very curious, then you'll end up doing both... Buying the book and then taking the course anyway.

...But to have these people constantly demand to know "why" and then accuse me of hiding something akin to the Wizard of Oz is just plain silly. It's like someone walking up to you and demanding, "I've never driven a car before. Tell me how to drive a car." Of course, you'd tell them to take the course and learn properly. If they got angry and accused you of "selling driver's ed courses," you'd think, "This is silly. You need to take the course to learn how to drive." When they continued to demand, you'd likely understand the fascination, and then you might say, "Well, this is a steering wheel, and this is the accelerator... This is the brake," and so on, but then tell them, "You need to take the course." When they angrily demanded to know why, exactly, they needed to sometimes make left-hand turns (because they're so much less safe than making right-hand turns) then you'd probably blink twice at them, think to yourself, "They just don't get it," and recommend that they take a driver's ed course and learn how to drive properly. You might even recommend a book on driving first. ...And when someone said to you, "You know what? This is stupid. I might not take the course at all... I think I'm just fine riding on the bus..." You'd think to yourself, "Sure, dude. Suit yourself... No skin off my back." Then you'd go get in your car and take it out for a spin, all while getting funny looks from all of the people on the bus.

The Rule of 120 was taught in my DIR-F class. If it's not in yours, ask about it, and I'm sure that they'll be thrilled to go through it all day long. They were for me. I found the class simply amazing. If not, then enjoy your spot on the bus. Some people prefer it there, so it apparently suits some people just fine. Maybe that's where you ought to be. Perhaps that's where you belong.

...Or you can be with us. Some people even sometimes drive their cars and sometimes take the bus... It's completely up to you.

Doesn't matter to me.

But if you ask me a question, then be prepared to hear the truth, 'cause I'm gonna give it to ya. And the truth is that if you want your questions about DIR answered, then you need to take the class. Any information that comes to you about DIR that does not come from GUE directly is questionable, and in my experience, often wrong.

So go get it directly. Or enjoy your seat on the bus. But those are the only two options that I've ever seen.

And that's the truth.

 

[MikeS]

gzscuba once bubbled...
First, don't most computers allow you to do a repetitive dive deeper than your first dive. Some people may say that this is okay, but I thought that most of the agencies frown upon this.

Gzscuba,

I apologies for using your comment as an example, my intent is not to pick on you and/or offend you in anyway, but to point out how not to use a dive computer.

A dive computer cannot allow you to do anything. All the computer does is provide you information upon which you should base your decisions. Dive tables work the same way; they will let you calculate the NDL limits for a reverse profile also. It is up to you as a diver to make decisions based on the information provided by the dive computer and your diving knowledge as well as your knowledge of how the computer works. You make the decision on if you want to make a reverse profile dive not the computer.

While many computers have alarms that warn you of certain situations, relying solely on a dive computer’s alarms and/or when it tells you to surface, to keep you out of trouble is dangerous.

While I don’t think computers rot your brain, they don’t prevent you from diving without using your brain. Nor do tables.

Mike

Mike

 

[gzscuba]

MikeS,

No offense taken. Right now I'm diving with tables, and maybe I'll buy a computer in the future. For that reason, I just wanted to explore what some of the pitfalls might be for diving with a computer.

It looks like as long as I continue to plan my dives properly, I'll be fine... I hope

Thanks for your comment,

 

[JeffG]

Disclaimer:

This is just an Exercise in Mathematics. It is not intended to be used to calculate a divers remaining NDL “on the fly”, but to generate a healthy discussion. Using a table meant for Square profiles and manipulating it for multi-level diving is beyond the table was designed for.



To use the PADI RDP(or any other table for that matter) to calculate multi-level dives, all a person needs to do is to calculate each level as its own dive with a 0 (zero) surface interval.

Now to take it one step farther: If you add up the allowable time and the depth a pattern emerges.

PADI – pattern of 110 (from 70-80, and then jumps around 115-120 just before and after the 70-80 ft range)

The other pattern is that the RNT (of the calculated dive of zero SI), subtracting the actual bottom time, is between 1 to 3 minutes.


So if we put 3 pieces of information together, we can have an “On the Fly” NDL calculation.

1: Total Dive Time
2: Max Depth (Rounded to the deeper multiple of 10, ie 88ft rounds to 90)
3: Current Depth (Rounded to the deeper multiple of 10, ie 58ft rounds to 60)

So if we use 110 as the combo depth/time magic number. (This is more conservative than the 120 rule) and we use 3 extra minutes per 10ft of depth change (again the most conservative number), we get the following:

NDL Time Remaining = 110 – Total_Dive_Time – ((Max_Depth – Current_Depth / 10) * 3) - Current_Depth

If the number is less than 0 (negative), you need to start ascending, and do some off-gassing

 

[wb416]

SeaJay once bubbled...


No, I specifically remember the event. It was discussed on Friday night, in class.

I've reviewed my notes from both classes (July & Sept 2002) and it wasn't covered. I like taking notes, so I'm sure that if we had covered it, then I would have written it down.

My point in saying this is that pointing someone to the class to get the info probably isn't the best thing. There's liable to be disappointment or frustration if it isn't covered. I was disappointed that "shooting a bag" wasn't covered in my first class, but we got to it in my 2nd class. Class dynamics have an effect on the flow of a "Seminar" or "Workshop"-style class. Perhaps GUE changing it to a cert class will change how and what is covered... not sure... just a supposition.

I think it's OK to share info from the class, even if you aren't an expert. If someone wants to know about the "Rule of 120" then share it with them with the caveat that your presentation of the info is as you currently understand it. Telling someone to take the class to get the info is a little weak and suggests to me that you're not confident in you're understanding of it, or withholding for other reasons.

Your example of "driver's ed" is amusing... It's OK to share your knowledge on driving or diving concepts with the person asking. It doesn't remove the benefit of taking the class. It may even spark their curiosity.

So, if anyone has a question about DIR-F or any other class I've taken, I'm happy to share the experience and info. If I don't know or didn't totally understand the concept, as presented in the class, I'll say so or make a disclaimer to that effect.

Let's not get caught up in this game of obfuscation called "Kiss my a$$, just take the cla$$". All of can be mini-ambassadors or amateur educators for whatever dive philosophy we believe in and share that info with others.

 

[SeaJay]

cwb once bubbled...


I've reviewed my notes from both classes (July & Sept 2002) and it wasn't covered. I like taking notes, so I'm sure that if we had covered it, then I would have written it down.

No doubt!

Well, it was covered in ours.

My point in saying this is that pointing someone to the class to get the info probably isn't the best thing.

...And you think that answering questions on the 'net is a better idea? Man, I can't understand that thought process, but to each his own, I guess. Don't say I didn't warn you.

Telling someone to take the class to get the info is a little weak and suggests to me that you're not confident in you're understanding of it, or withholding for other reasons.

I dive it every day. I trust my life to it. I am confident in my understanding of it. What I'm not confident in is being able to communicate it over the 'net. I can assure you that people will take it and twist it into something it's not, and when someone gets hurt, then it'll be your fault because you didn't cover something completely or you covered something else too much or you just plain lied, or whatever. The worst is that at that point, people will quote the misinformation (that was good information until it was misread) that you gave and say, "Those DIR guys are unsafe," and that "their practices are going to kill someone." Why would they say this? Because you taught them on the 'net. It's hard enough to communicate this stuff in person and with practice. I contend that it's impossible to do with words alone, and it's the exact reason that JJ doesn't teach people how to do this stuff in the book.

I can't believe that you're going to do this. Why not just tell people how to scuba dive? Why not just have 'em take a written test to get their OW certification, without ever even seeing the water?

Your example of "driver's ed" is amusing...

Uh... Thanks. It's also true. Can you imagine trying to certify someone for scuba online? Of course not. You'd tell them to go take the class.

But if you want to take on that responsibility, then feel free. I hope nobody gets hurt.

It's OK to share your knowledge on driving or diving concepts with the person asking. It doesn't remove the benefit of taking the class. It may even spark their curiosity.

Well, I feel the same, to a point. The difference between you and me is where to stop. When they start asking where you keep your spare set of keys, I recommend that you quit the conversation. Smile, tell them where they can take the course and leave.

Let's not get caught up in this game of obfuscation called "Kiss my a$$, just take the cla$$". All of can be mini-ambassadors or amateur educators for whatever dive philosophy we believe in and share that info with others.

Oh dude... You've never been down this road before, have you?

Don't say I didn't warn you...

 

[wb416]

SeaJay once bubbled...



Oh dude... You've never been down this road before, have you?

Don't say I didn't warn you...

Thanks for the advice... it's a good thing you know me so well and saved me from myself... especially since I just started diving and posting on scuba forums yesterday.... I guess I missed out on the "Superhero" pill in class, otherwise I'd have the discernment and wisdom to protect the masses....:doctor:

...Save the patronizing tone for someone else and let the rest of us lowly divers have discussions that'll expand our knowledge base. If you're not going to share the information, then your verbosity in this thread is meaningless.

 

[SeaJay]

???

Okay, my man. It's all yours.