PADI tables finally going away?

[D_B]

calculators .... is anyone using them?

you need to have some idea of the expected answer so you don't just blindly follow what it's telling you ... but much like a dive computer, you can practice with it before hand to get an idea of what the right answers to different problems are


ABS .. I don't doubt that early ABS might have been that way on dirt roads, but any modern system disables ABS on dirt roads just for the reasons you mentioned ... that same system also senses when your turning the wheel and the angle that your going verses the angle/rate that your asking for and applies the inside brakes to make up the difference

 

[ScubaSteve]

You may have mentioned this earlier and I missed it but I think it is worth asking considering how adament you are about only teaching computers.

1. Would you turn a student away if they showed up having purchased all their gear but with tables and not a computer?
2. What if a student has been e-learning before the calss and they make it clear they also want to learn tables so they have the basic and fundamentals of what a computer is doing. Do you kick them out of class? Do you tell them to take another course after your OW class? Do you keep only them behind to show them but not the others?

I am certainly not saying your method is wrong, but I certainly am saying I think it is imperative that a fresh OW student at least know the basics of diving tables. The physiological aspect of diving is huge and even though most do not fully understand the impact on the body, I would think that most do know the very basic impact that diving has on your body.

For the same reasons I don't teach underwater demolition, how to rebuild a regulator and underwater basketweaving to open water students. Sure, if a student has an interest in any of those subjects (except UDT), I can help them gain mastery after the basic class. But really, tables aren't needed by them to go diving and have a great time. I would rather spend more time on skills they will actually use to have a safe and enjoyable dive, like trim and the frog kick.

 

[Slonda828]

You are entirely correct that knowing the tables is not required as long as the diver has a working computer, but at a minimum they need to know what to do when it fails and they need to know enough to be abel to determine when it is feeding them false information and teaching tables is one of the quicker and easier ways to address both.

They also need to be able to use them on a rolling boat on a surface interval when they are tired from their first dive and then their computer craps out. Most of them do not know how to do so (even though I keep 4 kinds of tables in my logbook), so they spent the next three hours vomiting and getting sunburned while the rest of us dive. If people do not want to learn tables, then that is fine. They need to prepare to waste money, time, the contents of their respective stomachs, and their skin cells if they do not and their fancy computer goes **** up from a 4 dollar watch battery.

This same mentality of "divers don't need it" is why open water courses are half the length they used to be and people like me have to remediate new divers on skills over and over again when they do not magically grasp things in an 8 hour period. We are slowly turning dive training into the equivalent of hop-skotch or double-dutch.

EDIT: Should I have said tango uniform?

 

[DA Aquamaster]

The problem with the antilock brakes was not ABS, it was a design flaw in the original US designs...which has been corrected. It was a pulse rate issue.. long since corrected....

You are misisng the point, that at the time and in that circumstance knowing something about braking beyond just pushing the pedal to the floor was important.

Until we reach a state where recreational dive computers come with triple redudant computers using voting logic and have mean time between failures measured in years, the need still exists to know what to do when your comuter fails.

....Your second example is interesting, because there is a very easy way to o the same thing...even with antilock brakes.

Feel free to elaborate.

However, it is the classic "I am safer without seatbelts, because...." story.

No. Its not. Those tend to be stories about accidents where a random chance results in an exceptional occurence where the person survives regardless of a seat belt being used, not accidents where an intentional action took place. There is a significant difference.

 

[dmoore19]

That's a good analogy. I remember when they first came out as on our patrol cars - we discovered that they would cycle during hard braking on washboarded areas of gravel roads. This was unfortunate as the areas where cars normally brake on gravel are the areas that get washboarded the most since the braking forces contribute to the washboarding of the road. This discovery was made when several officers flew right off curves during high speed pursuits because the cycling brakes offerred basically no speed reduction on washboards. Great on ice, not so great on gravel.

So, I'd argue that while most drivers liek ABS and benefit from it, drivers who really know how to drive tend not to be the world's biggest ABS brake fans. Personally, I owe my life to NOT having ABS brakes. I was post law enforcement by then when I t-boned a car that pulled in front of me on the highway. I walked away from what should have been a fatal accident because I was able to lock the brakes, break the rear end loose and spin the car in order to aborb the energy along front and side of the car rather than head on. Talk about training taking over, but it would most likely not have worked in the time available with ABS brakes.

I'm not technophobic - I enjoy a dive computer as much as anybody (as a backup to solid deco and gas planning) and I certainly enjoy flying instrument approaches a lot more with a flight director or HSI than with just an artificial horizon or partial panel. But the point is I know how to do it with much less reliance on technology when the technology fails.

You are entirely correct that knowing the tables is not required as long as the diver has a working computer, but at a minimum they need to know what to do when it fails and they need to know enough to be abel to determine when it is feeding them false information and teaching tables is one of the quicker and easier ways to address both.

It is a good analogy. You are right! However, the general public knows about antilock brakes. They use them every day. Just as most divers use computers these days. For those who need special skills, such as law enforcement agencies doing special manuvers when driving the same can be said for Tech divers needing special skills needing more indepth information regarding decompression theory and the tables. I know how antilock brakes basically work but not all the details. I know how the tables basically work but not all the details. If I were to need the special skills for driving I would learn them giving me more insight as to the antilocks work. If I decide to do Tech diving, diving outside of general recreational diving, I will learn the the tables in detail giving me more insight. I think that people need the basic understand of the tables and how to use them, incase of computer failure. But I also have no problems with using a computer to help me enjoy my dive. Maybe after another 100 dives or so I will change my mind but for right now I feel safe relying on my computer. Especially if I planned the dive using the eRDP or the tables if I totally understand the deails of the theory or not.

 

[HowardE]

Personally, I think that a basic understanding of dive tables should be taught. I'm not suggesting that people need to try to plan multi level dives, but simple dive planning on a table is... well... simple really.

While the tables can be a quick overview, "this is a table... here's how to read it"... "understand that tables are not accurate, as they round off your depth to the next deepest depth, and also assume that you maintain the ascent rate prescribed and assume a square profile"

Sure a computer can calculate your repetitive dive profiles much easier, and most recreational computers have a dive planning mode... But the tables really do have the concepts of depth - NDL - Surface Interval Offgasing - and repetitive dive adjusted NDL's - right there all printed out. With the right explanation; they are easy to understand.

While I personally don't use a recreational dive planner (either I dive my computer, or use V-Planner and my computer), I know how to read one. At a quick glance, I can determine my NDL (or approximate decompression schedules) from a dive table (even for CCR dives with constant PO2), and have it in my mind just for the sake of having it. When instructors teach dive tables as some secret voodoo language that is really hard to understand; then it will be daunting and difficult for students to learn.

 

[DA Aquamaster]

It is a good analogy. You are right! However, the general public knows about antilock brakes. They use them every day. Just as most divers use computers these days. For those who need special skills, such as law enforcement agencies doing special manuvers when driving the same can be said for Tech divers needing special skills needing more indepth information regarding decompression theory and the tables. I know how antilock brakes basically work but not all the details. I know how the tables basically work but not all the details....

Where the analogy probably comes up short is that if the anti-lock features of the brakes fail, you at least still have brakes and they still more or less work the same way (push the pedal down and the car slows down).

What happens when a dive computer fails however? If it just shuts down it is obvious and you immediately ascend, do a safety stop and stop diving.

But what if the depth sensor is off or the computer is producing faulty deco information? That requires some knowlege, resources and problem solving skills, or at least enough knowledge of the conditions, site, tables and planned dive schedule to figure out the worst case scenario and do a sufficent safety stop to cover that eventuality. A buddy makes it relatively easy if you can compare computers and figure out which one is clearly wrong, but you need some basic information and pronblem solving skills to determine that.

Even in the abscence of a buddy (let's assume aliens abducted the buddy) if the diver listened to the briefing and knows the max depth of the site, he or she can estimate his or her average depth and using familiarity with their own SAC can estimate max dive time, even if he/she does not have a dive watch. Add to that some basic table knowledge (for example knowing that with your normal SAC that you can't exceed the NDL's above a max depth of X feet on the first dive of the day on an AL 80, knowing that a 5 minute stop at 10-15' will cover any deco I could get into on the second dive with an AL 80 down to X feet of depth) and the diver will have a pretty good idea how long to stay at a safety stop to ensure a safe ascent.

Teaching some basic table knowledge and some basic contingency planning will better prepare the diver for a computer failure. If you don't teach that, would you teach the diver to carry a redundant cmputer?

Consider another type of less obvious computer failure:

A decade or so ago, I was tooling along at 100' with an air integrated computer and noted I had 1870 psi left, which struck me as being a bit more than I expected based on 15 years of diving and familiarity with what I should have based on time, depth and SAC rate. So I checked 2 minutes later and had the same 1870 psi left, so I immedately aborted the dive and surfaced. It turns out the Uwatec quick disconnect had a sweet spot where it could come unscrewed just enough to trap the gas in the HP hose without venting it, so you got a pressure reading, but one that never changed.

Had I simply relied on the computer's faulty information and not validated that information with other knowledge and information (knowing what to expect for a reading, noticing when the reading I got deviated and noticing again that the reading had not changed - a potenail issue for some divers at 100' END) I potentially could have gone OOA later in what was planned to be a much longer multi-level dive.

So again, a diver does not have to know the intimate working details of a dive computer, but they do have to understand the basic operating principles and the potential failure modes.

As Howard states, a basic understanding of how tables work is part of the knowledge a diver needs to know to dive a computer safely rather than just being overly reliant on it.

 

[The Chairman]

Where the analogy probably comes up short is that if the anti-lock features of the brakes fail, you at least still have brakes and they still more or less work the same way (push the pedal down and the car slows down).

If/when a PDC fails, you still have gas to breathe. I see no discernible difference.

Had I simply relied on the computer's faulty information

You say this like mechanical SPGs don't do this on a regular basis. Are you telling us that you now dive multiple SPGs to avoid this scenario?

So again, a diver does not have to know the intimate working details of a dive computer, but they do have to understand the basic operating principles and the potential failure modes.

What they need to know is what to do when Murphy shows his ugly face. If you don't train them to USE the PDC, then they learn it by trail and error. Shame on the instructor who short cuts their student's training because they are too macho to use computers. They need to know what to do BEFORE it happens to them.

BTW, 3 years after ABS came out, there was a study done by insurance companies to ascertain the impact they had on insurance payouts. In essence, the difference amounted to non, nada and squat. The anticipated savings from ABS systems was simply not there. WHY? It became obvious that mechanical systems amounted to very little when a driver falls asleep or is drunk behind the wheel. In a conversation with Puff he pointed out that if you get bent once, you are %50 more likely to be bent again. Is it bad genes or does getting bent alter your physiology that much? More likely it's the same careless people who simply didn't learn from their first mistakes. However, I am certain that ABS has saved a life or two from the accidents that didn't occur. I know it's saved my butt (traction control) on at least one occasion.

Point? Like ABS, PDCs are simply a tool. I suggest that it's a good idea to learn how to use the tools you will be diving with first. Then you can go back and learn a little more about the history of diving and go dive with antiques if you like. Will I turn away a student who wants to learn tables? Nope. If that's his tool of choice, then fine. I will be the first to point it out when he arrives at a dive without his tables in tow.

For those instructors that teach ONLY tables... you are doing many of your students a grave disservice. Break free of the backwards thinking ideology that "old school" was somehow the "best school". Give your students the edge and help them to learn what that ascent alarm means. You'll make them better divers from the start.

 

[Jim Lapenta]

Does that include students who do not want ot spend the money on a computer. Or are content with using the tables and diving within those limits? I do discuss dive computers but will teach students how to use them if they decide to purchase one. I demo my Oceanic veo and show them my OMS bottom timer. Those are the only comps I currently own. The shop whose pool and hard gear I use has comps in their rental fleet but not in the pool gear. I see no problem with this.

One thing that perhaps I missed or has not been noted is a little item I read in Tom Leaird's Diving Fundamentals for Leadership and that is that when people use the tables and understand them they tend to be a bit more conservative and stay away from the NDL's. But how many, and yes myself included at times, will dive a computer right up until the yellow just pushing the red. Why must divers squeeze every last minute trusting the computer will keep them from getting bent. Especially when we know different comps have different levels of conservatism. And do these divers know just what those algorithms are based on or the fact that what may be ok for one diver in perfect shape, well hydrated, and well rested, may be very dangerous indeed for the out of shape, overweight, once a year vacation diver with a hangover?
BTW if a student of mine does buy one and wants to learn how to use it I do not charge for the extra time doing this. It's part of the class in my mind just delayed until they decide they are ready and then it's not generic info but specific to their new computer.

 

[dmoore19]

Where the analogy probably comes up short is that if the anti-lock features of the brakes fail, you at least still have brakes and they still more or less work the same way (push the pedal down and the car slows down).

What happens when a dive computer fails however? If it just shuts down it is obvious and you immediately ascend, do a safety stop and stop diving.

But what if the depth sensor is off or the computer is producing faulty deco information? That requires some knowlege, resources and problem solving skills, or at least enough knowledge of the conditions, site, tables and planned dive schedule to figure out the worst case scenario and do a sufficent safety stop to cover that eventuality. A buddy makes it relatively easy if you can compare computers and figure out which one is clearly wrong, but you need some basic information and pronblem solving skills to determine that.

Even in the abscence of a buddy (let's assume aliens abducted the buddy) if the diver listened to the briefing and knows the max depth of the site, he or she can estimate his or her average depth and using familiarity with their own SAC can estimate max dive time, even if he/she does not have a dive watch. Add to that some basic table knowledge (for example knowing that with your normal SAC that you can't exceed the NDL's above a max depth of X feet on the first dive of the day on an AL 80, knowing that a 5 minute stop at 10-15' will cover any deco I could get into on the second dive with an AL 80 down to X feet of depth) and the diver will have a pretty good idea how long to stay at a safety stop to ensure a safe ascent.

Teaching some basic table knowledge and some basic contingency planning will better prepare the diver for a computer failure. If you don't teach that, would you teach the diver to carry a redundant cmputer?

Consider another type of less obvious computer failure:

A decade or so ago, I was tooling along at 100' with an air integrated computer and noted I had 1870 psi left, which struck me as being a bit more than I expected based on 15 years of diving and familiarity with what I should have based on time, depth and SAC rate. So I checked 2 minutes later and had the same 1870 psi left, so I immedately aborted the dive and surfaced. It turns out the Uwatec quick disconnect had a sweet spot where it could come unscrewed just enough to trap the gas in the HP hose without venting it, so you got a pressure reading, but one that never changed.

Had I simply relied on the computer's faulty information and not validated that information with other knowledge and information (knowing what to expect for a reading, noticing when the reading I got deviated and noticing again that the reading had not changed - a potenail issue for some divers at 100' END) I potentially could have gone OOA later in what was planned to be a much longer multi-level dive.

So again, a diver does not have to know the intimate working details of a dive computer, but they do have to understand the basic operating principles and the potential failure modes.

As Howard states, a basic understanding of how tables work is part of the knowledge a diver needs to know to dive a computer safely rather than just being overly reliant on it.

you took a portion of my quote not the whole thing. I continued on saying that basic use of the tables is necessary, just not all the details for a recreational diver. Any piece of equipment can fail even an analog depth gauge or an spg. Even though I depend ony my computer just like I depend on my antilocks I still know how to use the tables and I still plan the dive using the eRDP or the tables just as I know how to drive without antilocks. I have 2 computers and I also have a redunant SPG. I use technology available and rely on it. But I still know how to use tables or an eRDP. And I do the plan before I dive.