Computer VS. Tables

[TN-Steve]

Using the tables, could you get an approximation of your pressure group this way?

1. After the dive, put your computer over into 'dive planning mode'
2. See what your NDLs would be for a couple of depths, (say 30, 50, 70) feet, and jot those down
3. Go to the tables and see what group would correspond to those NDLs. (rounding to the conservative side always).

That way, worst case, somebody now drops a tank on your computer, now at least you've got a starting point for figuring where you are at in terms of residual nitrogen and can plan from that.

If I were in that position, I'd probably bump it up by a group anyhow, just because...

Does this make sense?

Steve

 

[boulderjohn]

Thanks for the explanation. I did receive an eRDPml with my course materials, but the training itself was definitely computer centered.

Did you get the special computer diving booklet that included different knowledge reviews for chapters 4-5? Did you get a link to the online simulator? If not, then what they did was try to use up their old inventory of table materials while teaching the computer version of the course. In my experience, people requesting the table version of the course is a pretty rare thing these days. I haven't had to teach it for quite a while.

It really could be OK, as long as they really do teach all the content in the computer version of the course. I have heard stores of students being told to read the manual. That is not OK, because the student does not know what to look for when reading the manual. For example, the course goes over how to plan repetitive dives with a generic computer and tells the student to look for that feature on the specific model being used. When we have the many computer v. table debates on ScubaBoard, there are invariably a number of posts from people claiming that you can't do that with computers, when in fact you can do it with every computer in existence. Another example is emergency decompression. Many computer users don't realize that computers will guide them to the surface if the accidentally exceed their NDLs. The course again teaches them this concept and tells them to look for the specifics on their computers.

 

[LeadTurn_SD]

Using the tables, could you get an approximation of your pressure group this way?

1. After the dive, put your computer over into 'dive planning mode'
2. See what your NDLs would be for a couple of depths, (say 30, 50, 70) feet, and jot those down
3. Go to the tables and see what group would correspond to those NDLs. (rounding to the conservative side always).

That way, worst case, somebody now drops a tank on your computer, now at least you've got a starting point for figuring where you are at in terms of residual nitrogen and can plan from that.

If I were in that position, I'd probably bump it up by a group anyhow, just because...

Does this make sense?

Steve

It makes sense, but I still would not do what you are suggesting. Unless the tables are using the exact same algorithm as your hypothetical tank-crushed computer, you probably cannot switch from one to the other.

Best not to "mix and match".

What I would do was take my depth and time for the dive(s) completed that day, and compute Residual Nitrogen the old school way using your table of choice. The problem is that this will usually result in excessive conservatism, but at least that eliminates any potential conflict between the computer algorithm and table algorithm.... all of this assumes you recorded or remembered max depth and bottom times and surface intervals from the prior dive(s) that day...

Best wishes.

 

[TN-Steve]

It makes sense, but I still would not do what you are suggesting. Unless the tables are using the exact same algorithm as your hypothetical tank-crushed computer, you probably cannot switch from one to the other.

Best not to "mix and match".

What I would do was take my depth and time for the dive(s) completed that day, and compute Residual Nitrogen the old school way using your table of choice. The problem is that this will usually result in excessive conservatism, but at least that eliminates any potential conflict between the computer algorithm and table algorithm.... all of this assumes you recorded or remembered max depth and bottom times and surface intervals from the prior dive(s) that day...

Best wishes.

I see your point. I'm not sure I'd want to do it myself, Probably the safest thing would be put yourself into a 12 hour time-out, and then go from the tables at that point. I'm willing to speculate, but I'm not 100% sure I'd like to experiment on myself.

Steve

 

[MichigandiverJon]

Thanks everyone. Some good ideas but as Steve said I'm not sure I'd want to experiment on myself like that. I was just looking for a better way to track my dives on paper. Bottom line here I'm thinking is knowing the tables is great and necessary, but with logging multilevel computer dives leave the tables and letters out of it and write it out based on the computer info?

 

[Searcaigh]

I normally just log max depth and if on a reef, then I may add multi-level. I occasionally also mention critters and the depth I see them, primarily to relocate and photograph them.

 

[industrious95]

If you did a 5 minute safety stop after a 15 minute dive to 100 feet, the tables will give you a nitrogen load of 20 minutes at 100 feet.

Your computer sees 100 feet as 100 and 15 feet as 15. If you want to be conservative, by all means follow the tables, but the Suunto algorithms have been used and tested for many years. And Suunto, by the way, has a reputation as being a conservative computer.

 

[Skittl1321]

Did you get a link to the online simulator?

My PADI class had a book on computer use (it was pretty basic; I didn't feel like it taught that much, but then again, every computer is a bit different.) but there was no online simulator.
We spent a few minutes in class playing with the shop's computers and seeing how the dive plan mode worked, but that was it.

In my log book I just log max depth, average depth, and total time. And if I am doing a second dive what the SI was.
It's really more for notes than planning though.

 

[Hawkwood]

If you had the book "how to choose and use dive computers" there is a code printed in it that allowed you to download the "dive computer simulator".

The simulator leads you through various scenarios that show you how/what dive computers can do. When we teach, we typically spend a couple of hours with the simulator going through the scenarios.

 

[Skittl1321]

Oh, then I probably had access to it, but just never went there. It wasn't used as part of the class.