PADI tables finally going away?

[Paladin]

"In other words, while your conclusion may be correct, if it is correct I don't think you've reached that conclusion using sound logic."

My conclusion is based on 57 years of observing human nature. If you give someone an inch, they'll endeavor to take as much of that inch as possible and often more. For example, when the speed limit on the Interstate was 55 MPH, people routinely traveled at 65 to 70 MPH. Now that the speed limit is set at 70 MPH, they want to drive at 80 MPH or above. If a diver looks at his computer and it says he has XX minutes left until NDL is reached, it is simply human nature to try to take all that is given. When you consider that one diver's DCS threshold will differ from that of another, diving right up to the NDL over and over could be asking for trouble. Sooner or later, the law of averages will catch up to you.

Diving a multilevel dive using a square profile off the tables has a built-in conservatism.

By the way, the NDLs on my Oceanic Veo 100 computer match the NDLs on the PADI tables.

 

[The Chairman]

Pete,
Integrated circuits are, indeed, made up of microscopic transistors, diodes and resistors. Advances in electronics technology have not replaced them, they have just become increasingly smaller. I hold an A+ computer technician certificate. I know computers. I know their strengths and their weaknesses. And I know better than to put the absolute faith in them that you seem to have.

Dude, I have my A+ as well... I hope you don't feel that this gives you an upper hand in understanding micro-electronics. I have dabbled in electronics my whole life, designing and building numerous electronic gadgets and even a few useful devices.

A computer operates using logic gates made up of transistors.

Don't forget resistors, capacitors, oscillators, timers, and the list goes on. Humans are made up of neurons, ganglions, myelin sheaths, axons and more. Unfortunately, as we get deeper, these undergo a transformation due to narcosis that don't seem to affect a PDC. We can measure the degradation of the human brain to function as the pressure increases. It's a given, just as it's a given that pressure won't affect the PDC except as how it registers depth.

therefore, a bit of false information delivered to output or a bit of misread information going to input. The failure of an inverter can do anything from altering I/O data to causing a complete device failure.

Yeah, I'm going to call shenanigans right here. When PDCs fail, the failure is OBVIOUS. When humans fail, it's full of denial and excuses.

My "faith" in the tables is no more displaced or "mythical" in nature than your faith in dive computers.

It's not my fault that you have regurgitated myths about computers. I addressed them and pointed them out.

Pete, since joining SB, I have always respected you and I agree with you on many things, but this is one area in which you and I will never see eye-to-eye.

I feel no need to compel you to think like me. I always enjoy a lively conversation.

In my opinion, not teaching the tables (whether or not in conjunction with how to use a computer) is doing a disservice to students. If a diver understands the tables, he will be in a better position to decide if his computer is lying to him.

Shenanigans #2. Understanding deco theory and having a basic grasp of the physiology is all they need to see that the PDC is "lying" to them. Why push tables if the student isn't interested? I surely don't.

If a computer is to be used, it should be backed up by a watch and depth gauge. I carry two depth gauges: One mechanical and one capillary. A capillary gauge cannot fail.

I have seen no greater faith in all of Israel! I have seen them fail. That would be plural. There's a reason we don't use capillary tube depth gauges any more.

Also, a diver using a computer is more likely to push the NDL and come closer to a situation where a case of the bends becomes increasingly possible.

This is why NOT teaching divers to use a PDC is almost criminal. The primary rule of any instruction is to teach them to use the equipment they will be diving with. We are certain that many, many more divers will rely on a PDC. Why turn out divers who will take this risk because no one has taught them the proper way to use a PDC?

In 46 years of diving (knock on wood), and using the Navy tables, I have never been bent.

You have me by five years, but I have never been bent. Either is just a blip of anecdotal data.

As I look over the numbers,

You mean letters, doncha?

But I most certainly do advocate a thorough working knowledge of the tables, whether a diver decides to use a computer or not.

Good for you. I advocate teaching them in the gear they are most likely to be using. Hopefully, you teach them how to use a PDC in addition to the tables.

 

[Leadking]

I went on a 4 day trip with three computers, Explorer, VR3, and a ScubaPro. All three failed!
Almost $4k of worthless computers.

Tables? We don't need no stinkin' tables!

Yeah, right!

 

[notivago]

The dive master says to plan your dive predicated on 70 max, you now find yourself at 95 ft. While you're having to deal with refiguring your profile slightly narced, my PDC has made the adjustment on the fly.

I will call the dive on the spot, stay as much as I can at 5m depth and then surface and look for any signal of bends while I go over the table to see if I exceeded my NDL and to readjust the diving plans.

Get real. The bravado is so thick with some people that it makes it hard to wade through their posts.

Really? To me people that advocate for the table seem to be on the safe side and not on the daring side. They come across to me like someone that would have less bottom time, eventually call a dive, etc than to push to the NDL limits. This is more to be a coward than to be brave if you ask me. I myself am a coward.

WHAT??? I can run scenarios until my fingers ache, including variables on the mix and depth. I can even use different PDCs to see how they approach the same dive. This is the kind of myth that learning PDCs in your OW class should eliminate.

As you can see each computer is its own beast, mine does nothing of that, I can input the depth of the next intended dive and the gas mixture and it will give me the time I have, but I cant plan additional dives further.

Nothing replaces experience. However, if I need that tight of planning, I can always break out deco weenie, vPlanner and the like.

I didn't even knew what a vPlaner was until you mentioned, I googled and found out, cool, except it is paid for software, which means that not only you would have to buy the diving computer as you have to buy a device to run it on and the software proper.

Incidentally I do have the iPod touch, iPad and a net book on which I could run it on the boat, except that I would not bring any of those to the boat as they get very expensive around here. I would not cry a river if my RDP table go overboard, but any of those are a entirely different history.

But they were all multilevel dives and you now find that you can't do that third dive... but me and my PDC can.

But having the table at least I could dive. If I had to buy diving computers right of the bat on the OW, I would never be able to convince my wife into diving, even now that she has become a dive freak I got her to approve only one diving computer.

I don't provide an RDP in my OW courses.

Good thing that where you live having a computer is not a big deal.

Oh yeah... accuse me of nefarious intent all you want, but I don't sell PDCs. I teach PDCs because that's what my students will be diving with.

Again, good thing those computers come cheap to you. They are very pricey around here.

I don't buy into the macho "tables are better because real divers use tables" BS. Nor do I buy into all the other fallacious arguments you have presented.

I haven't seeing anyone saying that real man use tables, "au contraire", so the fallacy is yours being: Straw man - Wikipedia, the free encyclopedia

What exactly are the fallacies in my arguments? That computer are not easily accessible everywhere? How so? Do you think that if computers cost 6 times the amount they cost to you they would be something everyone would get? Because that is what we pay for them around here.

That it is easier to catch a simple instrument defect over a computer defect? How exactly any what of what I have told is a fallacy? If you computer is giving you bad info, how do you do to crosscheck it with someone else's? Pray tell me.

 

[notivago]

Notivago, you must have been told in your open water course that you have to plan every dive, regardless of whether you use tables or a computer to do the planning! Wearing a dive computer to keep track of the data related to the dive does not imply that the diver has no need to plan the dive. You must also have been told that regardless of the means used for planning the dive, the most conservative device used amongst those in the buddy pair/team/group diving together is what everybody follows. If one diver is following tables and the other is following a computer, the one following tables will control the dive; if both are wearing computers, the diver with the more conservative computer controls the dive.

1) Not all computers let you plan more than the next dive, so using computers in that case would not free you from the tables.

2) Following the most conservative device for depth gauge and timing device is meaningful, it is not meaningful for computers. If a computer is showing you bogus data, you simple has no way to tell it.

Since you have such a distrust of electronic devices, I hope that the timing device (watch or bottom timer) that you use to track your dive time is a high-quality mechanical one rather than a battery-operated electronic one, and that unlike a great many inexpensive mechanical timing devices, it keeps accurate time.

I have a healthy distrust to any device, electronic or not, I simply know that electronic ones are expected to have a higher failure margin than mechanic. Ask any Electronic Engineer, it is in the nature of electronic stuff to be a wee bit more faulty than mechanic, contrary than what people around here seem to believe, thinking that electronic stuff are infallible.

But, on fail, you can see that your watch is acting up, you can see that you depth gauge is bogus, but you have no way to tell that your computer is showing your stuff right(except of course time and depth).

 

[seaducer]

I like the fact so many people are learning to dive but not learning tables. Now when I pull mine out new divers sit around in awe and look at me like I am some kind of genius!

 

[notivago]

I'm a little confused by this experience of yours, notivago. Was the pressure gauge that failed an electronic one with a digital display or was it a mechanical one? If it was a mechanical one, don't you think that your story serves to show how mechanical devices can fail rather than how electronic devices can fail?

Anecdotal histories do not show that. In fact it was a mechanic device, the point being to show that even a device like the pressure gauge can be double checked if you have some sound data, depth and time are direct measures, they can be easily double checked, gas it is not nearly so easy, but it is still possible to have a clue that something is amiss.

With the computer, unless it simply stops working and go blank or acts up on more simple functions as time and depth, you simply have no tools to tell that it is not working properly, it can tell you for example that you are 15' from NDL when you are already entering it, then what?

The rule of the most conservative device does not work here, your buddy have done other dives this day? As deep and as long? Have both of you being diving at the exactly same depth? Yours can be the more conservative and yet it can be leading you to go past NDL because it is an second grade data based on other data, very personal to each person that bears the computer.

The only way to double check you computer is to dive yourself with 2 computers.

 

[DiveNav]

1) ........Ask any Electronic Engineer, it is in the nature of electronic stuff to be a wee bit more faulty than mechanic, .....

And your supporting data is?

Let me give you an example of the contrary.
Excerpt from Clare Application Note AN-145 - Advantages of Solid-State Relays Over Electro-Mechanical Relays:
".... In application, the lower reliability of EMRs leads to higher product life-cycle costs. This section describes the reliability advantages of SSRs over EMRs in terms of MTBF figures and the costs involved........
Cost Factor--------------------------------------EMR--------------SSR
Life expectancy (number of cycles)----------900,000----------5,000,000
.........."
EMR = Mechanical Relay
SSR = Solid State (electronic only .... NO moving mechanical parts)

Alberto (aka eDiver)

 

[Paladin]

"I have seen no greater faith in all of Israel! I have seen them fail. That would be plural. There's a reason we don't use capillary tube depth gauges any more."

Okay, Pete, I'll bite. How in the world does a capillary depth gauge fail? It's just a simple, clear plastic tube plugged off at one end. What is there to fail?

Capillary depth gauges still have a following among some in the tech crowd. Several divers I know still use capillary depth gauges for deco stops.

 

[notivago]

@NetDoc
Again you have mentioned human failing due to narcosis, how so? You are not meant to use your table while you are diving, you are meant to use before entering the water and thus can't possibly be affected by narcosis for its use.