Place of dive tables in modern diving

[lowviz]

OK, guys. I had my say.

Press on...

 

[tursiops]

If you start with a PDC, this insight is lost.

Isn't the point that you don't have to START with a PDC to teach about deco, why it is important, and how to calculate it; the PDC is the end point of the training, not the beginning. You start by talking about on-gassing/off-gassing, and how depth and time affect that. You can make a very simple but telling point with the Rule of 120, and then point out how that is not very accurate except for one depth and for a first dive. How do you get more accurate? Bring in the rule of 192000/Depth^2=NDL for the PADI RDP.....and ask them if they really want to be underwater, watching their air, looking for their buddy, minding their depth, and doing squares and division in their head? And then add that when the dive is over, they still have some nitrogen in them, thus reducing their limits for repetitive dives. How to keep track of all this? Once they realize it is a necessary thing to do, and reasonably complicated, bingo out comes the computer. it is the tool to calculate, not the means to understand.

 

[lermontov]

@stuartv I get that.

But would you consider that there is a subtle difference between being able to comprehend the values vs. being able to come up with something half-valid on your own?

you mean like ratio deco?

 

[stuartv]

@stuartv I get that.

But would you consider that there is a subtle difference between being able to comprehend the values vs. being able to come up with something half-valid on your own?

Sure, there is a difference. But, what are you going to do? Give students some problems like, for example: "Okay, you've planned these dives. What do you think you would get for an NDL on your 2nd dive if you change the SI from 1:00 to 1:30?" I could see throwing some questions at them like that then having them do the actual planning to see how close there guesses were. In which case, how does it teach them any more by doing the planning to check their guesses using tables instead of software?

Or what am I missing?

Yes, an entry-level Shearwater. I wouldn't be at all surprised if they beat deep 6 to an under $200 DC.

A new Shearwater is still a fair bit less expensive than what it seems like a fair number of people buy for their first computer.

And who said anything about "entry-level"? Your blanket statement that nobody can tell them what any computer will do for a given profile certainly didn't.

Lastly, Shearwater was just an example meant to represent any computer using Buhlmann w/GF (or any other published algorithm). There are Buhlmann/GF computers available that are less expensive than a Shearwater. So, your statement really was way off from the actual facts.

 

[stuartv]

you mean like ratio deco?

No. This conversation is strictly about recreational sport diving, where there are MUCH simpler ways to sanity check the NDL a computer is telling you.

 

[lermontov]

No. This conversation is strictly about recreational sport diving, where there are MUCH simpler ways to sanity check the NDL a computer is telling you.

just teasing

 

[lowviz]

...//... Bring in the rule of 192000/Depth^2=NDL for the PADI RDP..... ....

Where did you get that???


I use 222,222/Depth^2 as it is easy to remember. I found that equation by fitting USN NDLs using TableCurve 2D.

 

[tursiops]

Where did you get that???


I use 222,222/Depth^2 as it is easy to remember. I found that equation by fitting USN NDLs using TableCurve 2D.

I used the PADI RDP instead of the Navy tables. For the old Navy tables, 216000 is more conservative than 222222, even if it is not as cool.

 

[lowviz]

Ah. Yes, it is.

That is the beauty of first principles, you can do stuff with them...

 

[dmaziuk]

A new Shearwater is still a fair bit less expensive than what it seems like a fair number of people buy for their first computer.

And who said anything about "entry-level"? Your blanket statement that nobody can tell them what any computer will do for a given profile certainly didn't.

No, I said if you're buying an entry-level computer, then nobody can tell you how it'll behave. It is not entirely true, of course, as you can find a DSAT computer still somewhat within "entry-level" price bracket, and DSAT is a reasonably well understood. But you can't say that about "RGBM" ones, and let's face it: what the bleep is PZ+ anyway?

3 out of 4 DCs under $200 @ LP are not running DSAT (discount the genesis module-onlies), and it's worse for under $300. (I the tech. specs on i100 @Lp, BTW: "Algorithm: not specified by the manufacturer")

PS. Which ZHL+GF computers are less expensive than Shearwaters?