DIR and computers

[MHK]

NWGratefulDiver once bubbled...


To answer your question, I was told by a couple of different friends ... both of them 5th D regulars ... that it was no longer a part of the course for liability reasons. They got it from Sonya.

.. Bob (Grateful Diver)

Bob,

Let me clarify the point, and it has nothing to do with the catch-all "liability" reasons.

We are just simply more careful about how we introduce the topic and we now have to spend a bunch more time of parsing definitions. The fact is that as a general rule of thumb we consider all dives "decompression" dives, and by that we mean there should be some stop prior to surfacing. Most agencies teach 3 minutes at 15' whereas we teach 1 minute at 30', 1 minute at 20' and 1 minute at 10'. Putting aside the slight differences, the point being is that all agencies suggest some type of "stop" before you surface.

In discussing classes, concepts and so forth on various forums many play games of semantics so when the term "No deco dive" is used in the context of distinguishing between a recreational dive and a technical dive, some that want to misdirect the issue then jump in and say " well since you can't go directly to the surface it's a "deco" dive..

In the case that you site, it was widely discussed on this list as well as others, that one of Sonya's students made the casual comment in his trip report that he was taught to compute "deco on the fly", which then set off a firestorm of controversy in terms of definitions. FTR, the DIR-F class is a No-deco course, within the context of regularly used language of no-deco diving, ie; safety stops not mandatory decompression obligations..

Accordingly, some instructors now introduce the topic differently, they take great pains to waste time discussing semantics simply for internet posting purposes. In my class, I don't waste any added time worrying about how a trip report gets posted and I do in fact teach the 120 rule, as well as many other "rules" that apply to recognized No-decompression limits..

Hope that clears it up..

Later

 

[scubatexastony]

I do in fact teach the 120 rule, as well as many other "rules" that apply to recognized No-decompression limits..

When/who orginated the 120? and as far as that, the other "rules".

Thanx,
tony

 

[HammerNoMore]

MHK once bubbled...
Accordingly, some instructors now introduce the topic differently, they take great pains to waste time discussing semantics simply for internet posting purposes. In my class, I don't waste any added time worrying about how a trip report gets posted and I do in fact teach the 120 rule, as well as many other "rules" that apply to recognized No-decompression limits..

It sounds like when I find a class I can make it to I need to make sure it is either being taught by you or one of the other instructors so actually teach this stuff. It would probably be unfair to ask you which instructors belong to which category though.

James

 

[MHK]

scubatexastony once bubbled...


When/who orginated the 120? and as far as that, the other "rules".

Thanx,
tony

Dr. Robert Workman was working with the US Navy as early as 1958 and I understand the 120 rule was being used by the Navy in the early 60's. I'm not exactly sure if it was Workman, but as far as I know, someone in the Navy came up with it and I suspect it was Workman, but I can't be sure on that point..

As for the other rules, each "rule" probably has a different person/organization that "came up with it" so the question is to generic for me to address..

Regards

 

[scubatexastony]

to some of the hardheaded weekend converts, Mike.

I think it's a great idea to strive for a consistent training program, that stresses buddy awareness and team diving as DIRF introduces. I just find it a pain in the rear that most newly converted "students" assume it's a new revelation that was spawned by GUE. Kudos to your orgination and what it's doing to open the eyes of divers to become aware of just "BFS" and applying it in a 'team facade.

Thanx

tony (24,16,00)

 

[cornfed]

NWGratefulDiver once bubbled...

Um ... Drew ... I'm just trying to take part in the discussion. FWIW, I don't think anything I've said in this or any other thread on this board was said in a belligerent manner.

Bob,

If that was not your intention, I apologize. However, re-read your post I quoted. Do you see that could have been taken as a confrontational statement?

Drew

 

[Diver0001]

scubatexastony once bubbled...


When/who orginated the 120? and as far as that, the other "rules".

Thanx,
tony

It's a fluke of the US Navy tables, which date back 40 odd years.

Take a look at them some time. They show NDLs of :

60 ft - 60 min
70 ft - 50 min
80 ft - 40 min
90 ft - 30 min
100 ft - 25 min
110 ft - 20 min
120 ft - 5 min (or something like that. I'm working from memory here)

For most of that you can add up your depth and total bottom time and the equal 120 (or more). Some of us who pre-date computers and the "new" version the PADI RDP (the old one showed the same NDL's as the Navy tables) used to use the 120 rule or something very similar to avoid having to memorize the tables.

GUE just sort of reinvented the wheel (except they use avg depth instead of max depth) and packaged it in a magic wand. Add to that lots of secret-spy "this knowledge is too dangerous for mere strokes" innuendo on the internet (present company excluded) and the next thing you know people will actually pay money to learn it. I've been following internet forums for years and this is the first time I've seen someone actually explain what they're doing. Consider yourself lucky to have come across this thread.

R..

 

[scubatexastony]

I knew that, check my profile....
I was just making a point....

tony

24,10,13

 

[Atticus]

As long as everyones being friendly and sharing useful information...

I ran into a situation a couple of months ago where I overstayed my bottom time on a deco dive due to a buddy problem. First, I recognize that buddy communication, etc should be worked out well ahead of time, and I'll accept the abuse for getting into this situation in the first place.

That having been said, I was off the end of my pc planned profile and starting to really sweat the deco. I added 12 minutes at 20' on oxygen where two probably would have done.

Later I came up with a couple of rules of thumb for ratios of bottom time to deco time, at this altitude, at this depth, on this mix.

I understand that there may exist some formulas which are depth independent for coming up with a deco ratio. I'd be delighted to have an open discussion on the topic. Can anyone confirm that this is indeed the case?

If so, what class is it taught in, and is this a universal formula? Does it only work within certain envelopes (like the ratios I was playing with)?

Thanks for any light that can be shed on this.

Atticus

 

[Uncle Pug]

...you will find what you seek in a GUE Tech class... but..

no... I seriously doubt that you will get anyone to discuss it with you on Scuba Board.