Computer Algorithms, Objective Evidence of Whether One is "Safer"

[rjack321]

If you don't use a computer (and rely upon tables) that is fine, but unless you never do multi-profile dives, you're only kidding yourself

I haven't used a computer in a decade and do multilevel recreational, cave and decompression dives all the time. I'm not kidding...

 

[TSandM]

I haven't "used" a computer in about six years . . . I have VPM running on my X1, but rarely pay any attention to it.

The paper cited is an interesting one in that it compared the behavior of a variety of personal computers when subjected to a known set of profiles. But again, this isn't human data.

 

[JohnN]

I haven't "used" a computer in about six years . . . I have VPM running on my X1, but rarely pay any attention to it.

The paper cited is an interesting one in that it compared the behavior of a variety of personal computers when subjected to a known set of profiles. But again, this isn't human data.

Hardly a fair comparison. If you were diving GUE protocol, you wouldn't have done those dives without He.

 

[KeithG]

Could you look at this from a different angle?

Does DAN (or anyone else?) have data on reported DCS incidents that also includes the type of diving and the computer used?

i do not think this will answer the original question, but it may provide food for thought and discussion.

 

[Lorenzoid]

Could you look at this from a different angle?

Does DAN (or anyone else?) have data on reported DCS incidents that also includes the type of diving and the computer used?

i do not think this will answer the original question, but it may provide food for thought and discussion.

It is indeed interesting that the incident reports we see rarely note the type of dive computer. Of course, if they did, then the report would have to note what the computer indicated and whether the diver said he obeyed the computer's indications. That would add a lot of complexity to these reports. I suspect that this kind of data just isn't normally gathered when a DCS incident is reported.

Another thought is that DAN and others who publish DCS incident reports may not want their reports to be misinterpreted as suggesting the type of computer was relevant to the incident.

 

[redacted]

I haven't used a computer in a decade and do multilevel recreational, cave and decompression dives all the time. I'm not kidding...

Above or under water on the computer usage?

 

[Subcooled]

The following message is based on theoretical study more than experience. I have not dived deeper that 50mts and I have not done more than half an hour of deco. I am not a decompression theorist, either. While keeping these caveats in mind, read further.
_________________

For certain dive profiles it is possible to deduce and memorize conservative good approximations of the results of decompressions algorithms. This is called dive planning at home. A bottom timer is needed though. For my modest diving this seems to work just perfect. I do carry a cheap computer, but it's the time, depth and cylinder pressure that are relevant. I haven't dived The Big Sawtooth Tunnel, though so perhaps this does not work on every site. I have heard that some people use a ready made standard system called ratio deco.

The 'problem' with all algorithms is that they match statistics. Statistics made of severely lacking data. Several key factors are missing such as pulse, hydration level, and many more things. The result is a rough estimate. Minor differences are probably pure artifacts and as such irrelevant. The extrapolations outside the common diving envelope are... extrapolations to the unknown. But there's something glorious about beeing a crash test dummy, that attracts many young men. And some older. And some women.

Also take a look at the various parameters of VPM (and there are Many) and you'll understand that it can be made to produce anything you ever want. Your particular body may not comply, but that's a different issue. Other algorithms have parameters inside them too.

It would be more important to compare ones body against the standard body, prior to diving, to choose appropriate conservatism level.

Perhaps the "I'm tired now, next time I'll add some conservatism" approach would be a usable one. You could call this learning to know your body. The algorithm, for sure, does not know it.

 

[Subboy]

But no one is referring to the topic: is it there any tested study that reveals more risk in DSAT than in others computers?
And in the other hand, DSAT becomes more conservative when you approach 40 meters and go into a minor Deco?

 

[Agility]

And in the other hand, DSAT becomes more conservative when you approach 40 meters and go into a minor Deco?

Yes see A sense of algorithm - Divernet
It is an old article but so are the algorithms tested

Does DAN (or anyone else?) have data on reported DCS incidents that also includes the type of diving and the computer used?

AFAIK there is a DAN database, Marroni held a lecture in Vienna at the DAN Safety Stop presenting some preliminary data showing that many of the "undeserved" hits had occurred in dives with GF high >.75
http://ns1.daneurope.org/web/guest/send-your-dive-profile

 

[Subboy]