Are dive computers making bad divers?

[Storker]

No one is saying that because you have a computer, or because you fly the computer during your dive, that excludes an understanding of decompression technology or tables or anything else.

Totally agree. And IIRC, I've been arguing that as well.

And the latest posts by the OP suggested specifically NOT using a computer, but rather relying on doing math in your head by estimating the time you spend during the dive at various depths.

I think we pretty much agree that such a practice would be... not very smart.

I don't see how computers make bad divers - getting back to the original question.

I agree: computers in themselves don't. Blind reliance in a computer without a sound feeling of limits (which are rather quickly and easily conveyed with tables), OTOH, do.


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[scubadada]

OK, descend to 130 feet and spend 8 minutes, ascend to 100 feet and spend 8 minutes, ascend to 70 feet and spend 8 minutes, then ascend for the surface. I used EAN 28 so that the pO2 would be 1.4. Using 40/85, this is a deco dive. Using 45/95, this is arguably a no stop with a safety stop. I think we all get what averaging is, I would not use it on anything that was close to a deco dive, I'll stick with my computer.

MultiDeco 4.10 by Ross Hemingway,
ZHL code by Erik C. Baker.
Decompression model: ZHL16-C + GF
DIVE PLAN
Surface interval = 2 day 0 hr 0 min.
Elevation = 0ft
Conservatism = GF 40/85
Dec to 130ft (2) Nitrox 28 60ft/min descent.
Level 130ft 7:50 (10) Nitrox 28 1.38 ppO2, 116ft ead
Asc to 100ft (11) Nitrox 28 -24ft/min ascent.
Level 100ft 8:00 (19) Nitrox 28 1.13 ppO2, 88ft ead
Asc to 70ft (20) Nitrox 28 -24ft/min ascent.
Level 70ft 8:00 (28) Nitrox 28 0.87 ppO2, 61ft ead
Asc to 30ft (30) Nitrox 28 -24ft/min ascent.
Stop at 30ft 0:50 (31) Nitrox 28 0.53 ppO2, 24ft ead
Stop at 20ft 1:00 (32) Nitrox 28 0.45 ppO2, 15ft ead
Stop at 10ft 3:00 (35) Nitrox 28 0.36 ppO2, 6ft ead
Surface (35) Nitrox 28 -20ft/min ascent.
OTU's this dive: 34
CNS Total: 12.8%
49.7 cu ft Nitrox 28
49.7 cu ft TOTAL
　
DIVE PLAN COMPLETE


DIVE PLAN
Surface interval = 2 day 0 hr 0 min.
Elevation = 0ft
Conservatism = GF 45/95
Dec to 130ft (2) Nitrox 28 60ft/min descent.
Level 130ft 7:50 (10) Nitrox 28 1.38 ppO2, 116ft ead
Asc to 100ft (11) Nitrox 28 -24ft/min ascent.
Level 100ft 8:00 (19) Nitrox 28 1.13 ppO2, 88ft ead
Asc to 70ft (20) Nitrox 28 -24ft/min ascent.
Level 70ft 8:00 (28) Nitrox 28 0.87 ppO2, 61ft ead
Asc to 20ft (30) Nitrox 28 -24ft/min ascent.
Stop at 20ft 0:25 (31) Nitrox 28 0.45 ppO2, 15ft ead
Stop at 10ft 1:00 (32) Nitrox 28 0.36 ppO2, 6ft ead
Surface (32) Nitrox 28 -20ft/min ascent.
OTU's this dive: 34
CNS Total: 12.7%
47.9 cu ft Nitrox 28
47.9 cu ft TOTAL
　
DIVE PLAN COMPLETE

My apology, I did not fully understand this averaging system before I replied. My examples included best EAN mix for depth. I did not know this system was diving on air. Who dives air these days, particularly to deeper depths? Also, did not recognize that this was based on Navy tables, more liberal than DSAT/PADI or most commonly used Buhlmann ZHL-16C GFs. I reran the profile given based on air. Even the 45/95 simulation is clearly a deco dive. I have no interest in undergoing a chamber treatment for DCS. This averaging method seems absolutely reckless to me. I have over a 1000 dives using the DSAT decompression algorithm, a relatively liberal choice, I'm not averse to pushing it.

MultiDeco 4.10 by Ross Hemingway,
ZHL code by Erik C. Baker.
Decompression model: ZHL16-C + GF
DIVE PLAN
Surface interval = 2 day 0 hr 0 min.
Elevation = 0ft
Conservatism = GF 45/95
Dec to 130ft (2) Air 60ft/min descent.
Level 130ft 7:50 (10) Air 1.04 ppO2, 130ft ead
Asc to 100ft (11) Air -24ft/min ascent.
Level 100ft 8:00 (19) Air 0.85 ppO2, 100ft ead
Asc to 70ft (20) Air -24ft/min ascent.
Level 70ft 8:00 (28) Air 0.65 ppO2, 70ft ead
Asc to 30ft (30) Air -24ft/min ascent.
Stop at 30ft 0:50 (31) Air 0.40 ppO2, 30ft ead
Stop at 20ft 1:00 (32) Air 0.34 ppO2, 20ft ead
Stop at 10ft 4:00 (36) Air 0.27 ppO2, 10ft ead
Surface (36) Air -20ft/min ascent.
OTU's this dive: 21
CNS Total: 7.3%
50.2 cu ft Air
50.2 cu ft TOTAL
　
DIVE PLAN COMPLETE

 

[doctormike]

I agree: computers in themselves don't. Blind reliance in a computer without a sound feeling of limits (which are rather quickly and easily conveyed with tables), OTOH, do.

I think that we are in agreement with each other about the diving aspects of the discussion.

 

[phoenix31tt]

I agree: computers in themselves don't. Blind reliance in a computer without a sound feeling of limits (which are rather quickly and easily conveyed with tables), OTOH, do.

But would you agree that one doesn't need to learn how to use tables or even know what a table is to have a sound feeling of limits etc...


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[Storker]

But would you agree that one doesn't need to learn how to use tables or even know what a table is to have a sound feeling of limits etc...


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There's a lot of stuff " one doesn't need to learn". That doesn't mean that the old stuff (e.g. tables) is unnecessary and without value. Quite to the contrary IMO...


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[bfw]

I would say that for the average OW diver knowing the maths behind how the tables were achieved would be way too much. Now if you want to go deep or tech, knowing the additional information would probably be useful

As I said, that was in a Deep class. All divers should at least understand the principles behind the tables on a qualitative level
- what is happening while diving,
-what is happening during a surface interval,
-that the rate at which the body can deliver/remove nitrogen to/from different types of tissue varies,
-that the rate at which nitrogen goes into/comes out of solution varies by the difference between saturation at current pressure and the level currently in solution,
-that the problem occurs when the rate at which it wants to come out of solution in a given tissue exceeds the rate at which the body can remove it.

I always found it useful when teaching the tables to use a revolving credit as a partial illustration.

 

[phoenix31tt]

There's a lot of stuff " one doesn't need to learn". That doesn't mean that the old stuff (e.g. tables) is unnecessary and without value. Quite to the contrary IMO...


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Typos are a feature, not a bug

The NDLs for first dive are available on your computer...

The pressure groups are used as a way of referencing where to start for a repetitive dive

So tell me... what value would I gain from learning to use the table (aside from the fact that if I'm in a location and my computer fails I can use the tables after a few hours to do more dives)...

I learned and still know how to use the tables btw so it's not like I'm a computer only person... I just don't see how it helps me now...

I sure as hell know learning how to use a table didn't teach me anything I wouldn't learn while learning to use a computer (as it relates to deco and limits of course)

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[FinnMom]

You guys make it sound like the only thing on which two no-computer guys can 100% agree is that any 3rd no-computer guy is wrong.

It would be no surprise if extremely few average divers trust that they could possibly know enough about what they doing to try diving without a computer.

 

[Storker]

So tell me... what value would I gain from learning to use the table (aside from the fact that if I'm in a location and my computer fails I can use the tables after a few hours to do more dives)...

None, of coursre.

I learned and still know how to use the tables btw so it's not like I'm a computer only person... I just don't see how it helps me now...

You learned the NDLs on the tables, not on the computer, and now you're telling me it didn't give you anything. Am i the only one who sees the disconnect here?

 

[phoenix31tt]

None, of coursre.


You learned the NDLs on the tables, not on the computer, and now you're telling me it didn't give you anything. Am i the only one who sees the disconnect here?

You missed the edit?

I sure as hell know learning how to use a table didn't teach me anything I wouldn't learn while learning to use a computer (as it relates to deco and limits of course)


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