Place of dive tables in modern diving

[TMHeimer]

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.

Yeah, I can see that. Guess you just have to be careful--use your finger--or get them enlarged ( for old folks like me).

 

[KeithG]

I claim the wrong question is being asked and echo what a few people have already mentioned:
- dive table NDLs are simply an artifact of a deco algorithm
- so are computers
- They provide exactly the same information.
- Tables confuse most people, especially when a second dive is involved
- unfortunately, computers also confuse too many people (too dumb to dive?)

The real question is: should all divers have a firm grasp of basic deco theory? I. e. Deep and long gets worse! This nugget combined with knowledge of a few sample depth/NFL times would go a long way. Next piece of complexity would be to ensure they understood that subsequent dives on the same day will reduce your NDLs. This is the idiots guide to basic decompression theory. It's all they need to know.

None of this basic stuff requires knowledge of tables or how to operate a computer. Mentioning Tables is a red herring.

Learning how to work the tables for a subsequent dive is non trivial for too many people. Learning how to use the plan feature of a DC also seems to be a stretch for too many as well? Sigh...

Comitting to memory a few common NDL limits for your algorithm of choice is a good idea. This is what we should be arguing about.

I was taught on tables and used to know their NDLs. but I now know the NDLs as provided by my computer.

 

[lowviz]

...//... The real question is: should all divers have a firm grasp of basic deco theory? ...

No, just how long you can stay at the party.

...//... Mentioning Tables is a red herring.

********. One loses ones catch overboard fighting to find the red herring that one thinks one saw in the net. Nobody today gives a **** about tables...

...//... Learning how to work the tables for a subsequent dive is non trivial for too many people. Learning how to use the plan feature of a DC also seems to be a stretch for too many as well? Sigh...

Follow the DM on the vacation dive. Problem? What problem?

...//... Committing to memory a few common NDL limits for your algorithm of choice is a good idea. This is what we should be arguing about.

Aren't we? Does a simulator leave you with that???

...//... I was taught on tables and used to know their NDLs. but I now know the NDLs as provided by my computer.

This puts you at a serious disadvantage in this discussion.

 

[Eric Sedletzky]

Computers have revolutionized how divers dive and how their profiles look.

Back when there was only tables, divers tended to plan dives based a lot more on square profiles. If they dived a wall or a reef they tended to try and maintain a more even depth to make keeping track easier and truer. I know that I used to.

Now with computers, divers have a lot more freedom to do sawtooth profiles on rugged terrain or if going along a wall and see something interesting shallower or deeper they just go there without worrying about it, the computer will constantly adjust their NDL.
I don’t know if it’s physiologically better or worse, or if it matters? Is an NDL an NDL no matter how you slice it?.
They sure are having more fun diving, that’s for sure. A lot more freedom and less to worry about. However, it seems to me that going up and down all over the place isn’t a great idea, kind of like shaking up a soda bottle. I’ve read stuff about it and people warn against this.
But, people don’t seem to be too worried about it and do it without hesitation.
It would be interesting to know some stats whether computers have actually increased DCS in any way for people who tend to have squirrely profiles and fly their computers, as opposed to when people were stuck diving more steady depths with tables.

 

[KeithG]

Computers have revolutionized how divers dive and how their profiles look.

Back when there was only tables, divers tended to plan dives based a lot more on square profiles. If they dived a wall or a reef they tended to try and maintain a more even depth to make keeping track easier and truer. I know that I used to.

Now with computers, divers have a lot more freedom to do sawtooth profiles on rugged terrain or if going along a wall and see something interesting shallower or deeper they just go there without worrying about it, the computer will constantly adjust their NDL.
I don’t know if it’s physiologically better or worse, or if it matters? Is an NDL an NDL no matter how you slice it?.
They sure are having more fun diving, that’s for sure. A lot more freedom and less to worry about. However, it seems to me that going up and down all over the place isn’t a great idea, kind of like shaking up a soda bottle. I’ve read stuff about it and people warn against this.
But, people don’t seem to be too worried about it and do it without hesitation.
It would be interesting to know some stats whether computers have actually increased DCS in any way for people who tend to have squirrely profiles and fly their computers, as opposed to when people were stuck diving more steady depths with tables.

I disagree with your premise as a universal behaviour.

As a vacation diver I was taught to dive by half's. Half your tank into the (if any) current then return at half depth back to the boat. None of our dives were square profile. Always 2 level. But pur table based plans were worst case square profile.

We dived the to limit of the tables NDL but "knew" we "should" be safe since half of our dive was not at maximum depth.

But we were still a little nervous since we did not know how to calculate a real NDL for our split level dives.So how safe were we really?

Then we bought a dive computer and "discovered" that our rule of halfs diving pattern was extremely conservative.

 

[AfterDark]

Computers have revolutionized how divers dive and how their profiles look.

Back when there was only tables, divers tended to plan dives based a lot more on square profiles. If they dived a wall or a reef they tended to try and maintain a more even depth to make keeping track easier and truer. I know that I used to.

Now with computers, divers have a lot more freedom to do sawtooth profiles on rugged terrain or if going along a wall and see something interesting shallower or deeper they just go there without worrying about it, the computer will constantly adjust their NDL.
I don’t know if it’s physiologically better or worse, or if it matters? Is an NDL an NDL no matter how you slice it?.
They sure are having more fun diving, that’s for sure. A lot more freedom and less to worry about. However, it seems to me that going up and down all over the place isn’t a great idea, kind of like shaking up a soda bottle. I’ve read stuff about it and people warn against this.
But, people don’t seem to be too worried about it and do it without hesitation.
It would be interesting to know some stats whether computers have actually increased DCS in any way for people who tend to have squirrely profiles and fly their computers, as opposed to when people were stuck diving more steady depths with tables.

Saw tooth profiles at least from my perspective are the BIG advantage to diving PDC's . If PDC's didn't allow divers to perform saw tooth profiles with relative safety I wouldn't own two! It is PDCs not nitrox that has allowed me more time underwater. Nitrox can extend a divers bottom time only if the diver is not a gas hog like myself. Nitrox gets used up as quick as 21% so for me it's a wash, but being able to dive different depths when possible saves me air and increases my time underwater. Tables are just not as good as PDCs for that particular job.

 

[rhwestfall]

 

[rhwestfall]

 

[rhwestfall]

 

[CT-Rich]

Hey, feel free to run tables in your head. Not gonna be my first choice. How reliable are you going to be calculating deco at 90 fsw? The failure rate on DC is really low, compared to the failure rate of a person.

Here is my original pocket table. On the right is my current PDC. Which one of these do you think I could more accurately apply at 90’?

475F5D29-D267-415A-907A-62393EB88A9A

• CT-Rich
• Feb 18, 2018