Please explain (teach me)

[boulderjohn]

I have no problem with computer only courses (that when well done equip the new diver with a way to use a valuable tool, but leave them unprepared for when something goes wrong with their computer), but such courses don't really save any teaching time.

I have never heard of anyone advocating such teaching for the purpose of saving time.

No matter what, one is required to teach at least the basics of decompression theory. That is the same no matter what. In addition, one must teach tables (or the electronic version), computers, or both.

I don't know anything about the SDI program, and I have never taught the computer version of the PADI course, which is an option for the student. I have, however, reviewed the outline of the PADI computer OW course, and it is extremely thorough. The student will come out knowing a lot more than what to do when the computer fails.

 

[ianr33]

Today's divers are increasingly using this capable and versatile tool to plan and execute their dives. Their use and how to avoid their abuse should be an integral part of every class. Many see this as "dumbing" down the class, I see it as showing due diligence in teaching them how to use a great tool.

I think the training agencies are missing an opportunity when it comes to computers.

How long will it be until I am not allowed to dive without proof of
"computer certification" ?

Oh you may laugh, but its already happening with drysuits and solo diving and sidemount.

 

[Bubbletrubble]

I just re-read the Elite T3's manual. There are only two stops: safety and deco. Safety stops are optional and you won't be penalized for it by the computer. Deco stops are mandatory and if you were to violate the deco stop (i.e. skip it or not following the depth/timer or both), the computer will lock out for 24-hrs before it will work again. There are no mandatory safety stop versus optional safety stops.

Does the manual set forth ascent rate guidelines and discuss the consequences of exceeding recommended ascent rates?

 

[The Chairman]

The T-3 is one of my favorite PDCs and here's the rub...

The shallow stop (it calls it this) can be set for 3 or 5 minutes.

There are also settings for adding a deep stop and at what depth you want to spend your shallow stop. Indeed, it can show a deco stop at 15 ft and not 10.

Let's face it, walking up a hill requires "decompression." The accepted usage of "decompression stop" and "safety stop" has to do with the prediction of a model that you will bend as a result of a direct ascent to the surface at the approved rate of ascent in the former situation and that you will not in the latter case.

That's "old school" thought. As I said, many of us view all dives as decompression dives and all stops as decompression stops. Some are optional (safety) and some are obligatory (mandatory). Telling him that he is wrong about this is to show a complete misunderstanding or ignorance of how some teach this concept.

I agree with you completely. Unfortunately many instructors are using dive computers as a way to minimize (and even eliminate) a subject that takes them too long to get across.

I haven't met them. You must be exposed to more shops than I am here in Key Largo.

I have no problem with computer only courses (that when well done equip the new diver with a way to use a valuable tool, but leave them unprepared for when something goes wrong with their computer), but such courses don't really save any teaching time.

Unfortunately, the clarion cry that using PDCs dumbs down a course has severed communications on several levels. What was possible if the PDC hadn't been the butt of agency's blind phobias is now almost past. There are a number of us who feel no need to teach tables and spend the time discussing the ins and outs of diving with a PDC.

 

[Blackwood]

You may or may not get a DCS hit by skipping a Safety Stop. I'd like to see somebody does a 45-minutes dive at 150-ft and skip a Deco Stop while not getting the bend.
.

Which one?

I'd be willing to bet I could blow off my 40' stop on such a dive without substantially increasing the statistical likelihood of developing DCS.

Care to join me?


A bit hyperbolic, yes, but really goes to the meat of a poorly understood concept.

Decompression methodology is all theory-based. The only guarantee you won't get bent diving is by not diving.

So called safety stops were originally used because it was observed that divers were vastly exceeding modeled ascent rates. They can be used to hedge your bets. So can conservatism in models. So can holding margin against ascent rates. How does it all work? By doing more in-water-deco.

A safety stop is a stop during which you decompress. Changing the name based on whether or not they are mandatory seems silly to me, especially considering that "mandatory" is a moving target.

 

[Thalassamania]

As I have often said, what needs to be taught is decompression theory and at least one model. Tables are just snapshots of a model and computers are just cartoons, both are potentially effective ways of interfacing with the model and each has its place. I've been saying that since well before the Dive Computer Workshop in 1989 that moved dive computers from vodoo that all the agencies opposed to acceptable devices in the course of three days.

Your say that the idea of differentiation of "stops" into decompression and safety is somehow "old school" yet all you do is change the name to "optional (safety)" and "obligatory (mandatory)." That clarifies nothing, it just introduces new terminology that creates further confusion.

The real point is, as I mentioned, that all reductions in pressure (remember walking up a hill?) result in decompression and the accepted usage of "decompression stop" is: "the prediction of a model that you will bend as a result of a direct ascent to the surface at the approved rate," while "safety stop" are made to off-gas when that is not the case.

How that shows "a complete misunderstanding or ignorance of how some teach this concept." is a topic that I'd like you to explore further.

Which one?

I'd be willing to bet I could blow off my 40' stop on such a dive without substantially increasing the statistical likelihood of developing DCS.

Care to join me?


A bit hyperbolic, yes, but really goes to the meat of a poorly understood concept.

Decompression methodology is all theory-based. The only guarantee you won't get bent diving is by not diving.

So called safety stops were originally used because it was observed that divers were vastly exceeding modeled ascent rates. They can be used to hedge your bets. So can conservatism in models. So can holding margin against ascent rates. How does it all work? By doing more in-water-deco.

A safety stop is a stop during which you decompress. Changing the name based on whether or not they are mandatory seems silly to me, especially considering that "mandatory" is a moving target.

Exactly.

 

[The Chairman]

Your say that the idea of differentiation of "stops" into decompression and safety is somehow "old school" yet all you do is change the name to "optional (safety)" and "obligatory (mandatory)." That clarifies nothing, it just introduces new terminology that creates further confusion.

:gans:​

"Safety" is what muddies the picture. "Its called a safety stop, but you are still safe if you omit it" is the height of waffle speak. You might find "Waffle Speak" to be acceptable, but I don't. They are all stops and decompression will occur, ergo they are all deco stops. Some are optional, while some are mandatory. I shouldn't have to define "optional" or "mandatory" for the student as you would have to define "safety" that you don't need to do to be safe. THAT'S what's confusing to a new student.

Calling one "safe" and the other not kind of implies that I should skip the other so I will be safe! Shenanigans. It was a poor choice of words by the old school. The new way is much simpler and intuitive. I'm surprised that you can't see that.

 

[Bubbletrubble]

Guys, must we have a semantic/ideologic argument in the Basic Scuba Discussions forum?

 

[Scott L]

Oh, boy!

 

[Thalassamania]

I dislike the use of the "safety" stop term also ... but from the opposite perspective.

Safety means "without risk" and by making a "safety stop" you do not eliminate all risk, you just lesson it. I argued hard against that term, and I lost. But that was years ago and that has become the accepted terminology so, for clarity's sake I begrudging adopted it.

I agree, it is a semantic argument, but unfortunately it is one that confuses many new divers. I hope a short exploration of the issues will help with some of that confusion.