Place of dive tables in modern diving

[TMHeimer]

Divers are mostly not rocket scientists. Tables are highly error prone at the human level. Do you have an item on your checklist to have your table calcs reviewed by another pair of eyes?

The protocol I have in mind doesn’t require a computer. In any case the buddy fallback is sound. You generally do deco dives with the same buddy during the day and will be planning to do the same stops.

"Highly error prone"? If I can understand them and use them correctly anybody can. Ask my wife.

 

[agilis]

"Highly error prone"? If I can understand them and use them correctly anybody can. Ask my wife.

I don't do deco dives anymore. Haven't done for quite a few years. When I did there either were no computers or they were widowmakers, bendomatics.

Divers are mostly not rocket scientists. Tables are highly error prone at the human level. Do you have an item on your checklist to have your table calcs reviewed by another pair of eyes?

The protocol I have in mind doesn’t require a computer. In any case the buddy fallback is sound. You generally do deco dives with the same buddy during the day and will be planning to do the same stops.

I don't do deco dives anymore. Haven't done for a couple of decades. When I did there either were no computers or only crude instruments, widowmakers, bendomatics. I first planned the dive and followed the plan. I used the tables conservatively, along with a dive watch I still have, a great big pillowcase Seiko I bought at a PX, and a lot of hang time.

 

[boulderjohn]

"Highly error prone"? If I can understand them and use them correctly anybody can. Ask my wife.

It's not a matter of understanding. I taught the PADI tables to hundreds of students. I would guess that 75% of the errors occurred when people misread the numbers or columns as they did the calculations. It was really easy to get the wrong row or column because everything was so small.

 

[Eric Sedletzky]

It's not a matter of understanding. I taught the PADI tables to hundreds of students. I would guess that 75% of the errors occurred when people misread the numbers or columns as they did the calculations. It was really easy to get the wrong row or column because everything was so small.

As I remember from DM class the wheel was even worse.

 

[lowviz]

This thread is becoming interesting to me again. I came from the very end of the tables, brass & glass, and timer set. But let it be known that I now dive DC's exclusively (but with a good sense as to how they are behaving).

Yes, tables have now become a retro approximation to one's dive as they are horridly discrete approximations. A continuous approximation approach (DC) has the potential for being far more accurate with respect to giving more downtime.

But I still see the value in either approach until the dive simulator approach is properly explained to me.

For anyone with serious experience with a simulator, what is the take-away (other than being fascinated by the bars, color changes, and getting the concept that one's nitrogen load increases with depth and time)?

What are the "simulator" rules of thumb and how does a simulator present and reinforce those concepts?

 

[boulderjohn]

As I remember from DM class the wheel was even worse.

I learned how to use the wheel twice: for my DM certification and for my instructor certification. The wheel had a system for calibration--if the dot on one part was inside the circle of another, you were supposedly good to go.

On my instructor exam, I carefully did a wheel based problem and came up with an answer exactly halfway between two of the choices on the multiple choice answer. I did it again and again, and I came up with the same answer each time. I figured I had a 50/50 chance and went with one of them, but I picked the wrong one. The examiner had to go over my wrong answer with me, and he took his wheel and did everything the way I did, coming to the correct answer. I handed him my wheel and asked him to do it again. He got the same wrong answer I did.

 

[Compressor]

I learned diving in the early 80s. There was no computer except the scubapro decompression meter. Once dive computers came into the diving sphere I welcomed it but never forgot the use of tables. I used to carry tables with me while diving but these days, I dive with 2 computers (especially in multi-day, multi-diving days).

When I was teaching diving to students, I always showed them how tables work. Then we dove with computers and post dive the students really appreciated the utility of the dive computer.

If someone does not know what NDL means on a dive computer and why it might go into error mode, it tells me that they don't understand physiology too well. They don't have to know a lot of details but just need to understand the basic concepts once they submerge.

 

[tursiops]

This thread is becoming interesting to me again. I came from the very end of the tables, brass & glass, and timer set. But let it be known that I now dive DC's exclusively (but with a good sense as to how they are behaving).

Yes, tables have now become a retro approximation to one's dive as they are horridly discrete approximations. A continuous approximation approach (DC) has the potential for being far more accurate with respect to giving more downtime.

But I still see the value in either approach until the dive simulator approach is properly explained to me.

For anyone with serious experience with a simulator, what is the take-away (other than being fascinated by the bars, color changes, and getting the concept that one's nitrogen load increases with depth and time)?

What are the "simulator" rules of thumb and how does a simulator present and reinforce those concepts?

Dive Computer Training
For a few bucks, you can choose your computer and simulate to your heart's content.

 

[lowviz]

...//... They don't have to know a lot of details but just need to understand the basic concepts once they submerge.

Well this is my point. It seems that today one only need to obey one's DC. Exactly what are the basic concepts, today? Is how long I think I can remain at this depth one of them?

Years ago, we were shown how tables can be approximated by the 120 rule. But we were also shown that the 120 rule is a linear approximation and will only be 'exact' at one given point. The data that it was approximating formed a curve so it was an awkward fit.

The simplest curve approximation to the USN NDL curve that I could find was: 222,222/(depth)^2 That will approximate the US Navy air tableNDLs over a rather surprising range.

Someone got it right earlier, tables on the surface and computers underwater. but I remain curious, does the dive simulator leave one with a feeling of how long one can stay at a given depth?

Again, what are the dive simulator's stated take-aways? If not, is one just supposed to run a bunch of simulations and come out with a good "feel" for it?

 

[oldschoolto]

I don't think anyone is saying that DC are no good or should not be taught and used... What I'm saying is that every diver should know the basics of diving without one and how to safely get to the surface... That's all... Simple I think...

Jim..