Place of dive tables in modern diving

[lowviz]

...//... Commercial divers study air tables, nitrox tables and also decompression treatment tables. Same is true with military diving community. ...

Both do a lot more than that. Get yourself a free subscription to Underwater. (ADC International) They are fun to watch, highly competetive company-vs-company and research driven to maximize profitability. Dives are missions. Repetitive dives seem to be better done as saturation dives. Secret gas mixes...

No clue on military, any similar publication?

Nether commercial nor military has anything (that I can see) to do with recreational diving, but they are fun to watch.

 

[tursiops]

Why is it that professionals are spending time on something that is supposedly antiquated and amateurs are embracing what is new?

Check out commercial dive practices and military dive practices (like the Navy Dive Manual). Much/most of the work is square profiles, tables are fine. In fact, the most recent Navy Dive Manual (rev 7) has a nice chapter on dive computers and points out the advantage is "The NDC credits the diver for time spent at depths shallower than the maximum depth of the dive. This greatly increases bottom time." Sound familiar? Perhaps they are just catching up....

Progress is great but we are talking about progress driven by an industry that has always struggled to create customers.

This is your assertion. Much of the major innovation progress has come from within the diving community and the manufacturers jumped on the bandwagon. The manufacturers are good at developing and extending and hardening, but their innovation tends to be incremental, not a step-function. Take a look at the history of technology transfers between and among commercial, military, recreational, and technical diving communities. For example, http://tos.org/oceanography/article...r-in-diving-based-on-a-review-of-the-noaa-div

 

[J-Vo]

I took my OW in 1996. We were taught completely on tables. We did repeated exercises until we pretty much had them memorized. We were told in excruciating detail what it would be like if we exceeded limits from veins exploding like soda bottles to the skin on our necks ripping loose do to air expansion when ascending too fast (60 fpm).

At no point was I taught a thing about decompression science or why the table was the law. Sure we got the generic boyle's and Dalton's law, but no deco theory.

I don't understand why everyone seems to think teaching the tables is the same as teaching deco theory. Or for that matter that it's impossible to teach deco theory without tables.

 

[tursiops]

I don't understand why everyone seems to think teaching the tables is the same as teaching deco theory. Or for that matter that it's impossible to teach deco theory without tables.

^^^This^^^

 

[boulderjohn]

I took my OW in 1996. We were taught completely on tables. We did repeated exercises until we pretty much had them memorized. We were told in excruciating detail what it would be like if we exceeded limits from veins exploding like soda bottles to the skin on our necks ripping loose do to air expansion when ascending too fast (60 fpm).

At no point was I taught a thing about decompression science or why the table was the law. Sure we got the generic boyle's and Dalton's law, but no deco theory.

I don't understand why everyone seems to think teaching the tables is the same as teaching deco theory. Or for that matter that it's impossible to teach deco theory without tables.

As Josh point out so nicely, there are two different things that need to be taught:

1. Decompression Theory--why nitrogen builds up in the tissues, why it is released with a proper ascent, and why that matters.
2. How to plan and execute dives in accordance to decompression theory.

You need to teach both. For the second item, you can teach tables, you can teach computers, or you can teach both. Those teachings are independent of the instruction for the first item.

For years, people taught both of them at about the same time, and people mistakenly believed that they were really learning only one thing--they could not differentiate between learning decompression theory from learning how to manipulate tables and mistakenly believed they were the same thing. People who learned that way and were later taught to use computers often mistakenly believed that they only understand how computers work because they had earlier learned how to manipulate tables, when in fact they understand how a computer works because they happened to learn decompression theory at the same time that they learned to manipulate tables.

 

[dmaziuk]

People who learned that way and were later taught to use computers often mistakenly believed that they only understand how computers work because they had earlier learned how to manipulate tables, when in fact they understand how a computer works because they happened to learn decompression theory at the same time that they learned to manipulate tables.

ITYM people mistakenly believe that they understand how computers work because they had earlier learned how to manipulate tables.

Looks to me like the mental leap from a constant number looked up from a fixed row and fixed column, to the changing digits on a computer screen, is way too big.

 

[lowviz]

Need to take one more step back. The issue, as I see it, is first teaching the interaction of depth, time, and the idea of nitrogen loading. I was first shown this using tables as examples without any ability on my part to manipulate tables whatsoever.

I found it far more clear being taught that way. Once I had the whole idea of what was important, we got our computers. I found myself staring at the screen with very little comprehension for the first few dives. But I did have a fundamental feeling for how long I could be down...

 

[MargaritaMike]

Show of hands: how many people looked at that page in their computer manuals, and how many of those manuals had the numbers spelled out?

 

[boulderjohn]

The issue, as I see it, is first teaching the interaction of depth, time, and the idea of nitrogen loading. I was first shown this using tables as examples without any ability on my part to manipulate tables whatsoever.

And so that can't be done using the computer simulator program that shows the interaction of depth, time, and nitrogen loading? It can only be done with the tables?

So I assume in making this comparison you must have looked carefully at the computer simulation program so that you could see its faults. Perhaps you could take the time to describe what you saw in that program that makes it not work as well as the tables.

 

[MargaritaMike]

I still have the wheel in the back of my logbook to scare instructors, although any recently minted instructor wouldn't have a clue what it is.

I still carry my wheel with me on trips. I don't use it except to get on the boat, get my wheel out, and ask the Dive Guide (with my wheel visible) something like "We are going to do multi-level dives, right?" The looks that I get are often worth the price of the dive. Then I'll break out my computer and back-up computer and everyone has a good laugh. It doesn't mean that I know diddly-squat about dive planning or diving at all, but I have a computer so they are happy.

Having drilled hundreds (maybe thousand(s)) of students on the use and understanding of the tables back in the late 80's and early 90's, I have (or at least had - I'm getting older) the tables pretty much memorized (both sides). Being a mathematician, I am pretty good with numbers, and I still am constantly recalculating bottom times when I'm doing rec diving with a non-square profile. I use a "base" number and then use a + or - calculation based on time/depth. It's VERY rough, but I can come relatively close to my computer. This is all based on tables.

With that being said, I am learning to relax my brain a bit these days and just check my computer from time-to-time. If something doesn't look right all of a sudden, then I would assume that the computer COULD be malfunctioning and check the other computer. It hasn't really happened yet, so I just keep THAT plan in my playbook.

I don't think that someone HAS to know how to use tables before they use a computer, but I DO think they MUST know the concepts the tables or computers are designed to be use for.

None of this really addresses IMHO what is the important thing about using a computer OR tables, and that is on-gassing and off-gassing and what's happening to your body when you dive. Again, IMHO many newly certified divers have little or no concept of what is really happening when they are diving, and DCS is some semi-mythical illness that only advanced divers get because they do decompression dives. Just for fun, the next time you are with a group of people on a boat or similar place, ask someone who appears to be new, or even an oldie, what's happening or has happened when a diver get hit with DCS. Ask them in a way that you are trying to get a better understanding of it and want multiple explanations. If they don't know, it may be a brief teaching moment. Another question to ask is "How many compartments does YOUR computer consider in its calculations? Mine uses X". These questions are not meant to be judgmental. It may alert you to someone you might want to watch if you are a dive professional. There are all kinds of ways to determine if a person understands what is happening physiologically when they go diving. I think it's something we should ALL know or at least have a fair understanding of.

Someone earlier said know how to use the tool that you use. That is important. More importantly, IMHO, is why are you using this tool? What does it really tell you?

I agree with the idea that the recreational dive industry is based on numbers. It's almost like a pyramid scheme. The people at the top who are getting a slice of every pie are making money. The guys in the trenches (instructors) for the most part.... not so much.

Before everyone jumps on saying how wrong I am about this point or that point, just remember, this is MY OPINION. It's probably not worth the paper it's printed on.

Cheers -