Any proof that dive computers improve safety?

[D_B]

DrBill ... I think he's referring to your comment about "a long deco dive"

 

[Wookie]

Well, I am looking for a different kind of accidents. Nor for ones that could be caused by computers, but for those that could be PREVENTED by computers. So I would take as an evidence simply a statistically significant difference in odds ratio to have a DCS accident with and w/o a comp.

As for the rest of what you said, I agree with most of it except that non-square profile dives are not that complex with tables. In my estimate, approx. 3/4 of all Caribbean dives are done along corall walls (most of Bonaire, Curacao, Roatan, Utila, Grand Cayman off Turtle Farm and Cobalt Resort, etc) when you go one way at 55-75 ft and then return at 35-45 ft. These dives are fairly easy to plan since they could be treated as two square dives with zero surface interval. I bet comps use the same algorythm.

You are making stuff up, now. Are you telling me that the Caribbean is the only place computers are used in place of tables, or the Caribbean is the only place that counts? Or that divers only get bent in the Caribbean? I would argue that your 500 dives hardly makes you an expert on Caribbean dive sites. I've been to about 20 Caribbean destinations, and worked in 10, and I wouldn't say that over half are walls, and it might be no more than 40%.

You've narrowed the field too much. Every time someone comes out with an answer to your question, you change the question. Every time someone qualifies their answer, you qualify the question. Let me put it straight. No-one has published data that says diving computers is any safer than diving tables. There is no compiled data available to support such a study if someone wanted to perform one. Collecting data to perform the study would likely be cost prohibitive, given the likely outcome of the study. The outcome doesn't really matter, because most divers like to use dive computers anyway because they are easier than tables. Dive boats and resorts require the use of computers for reasons other than safety, although safety may be the reason cited, it's an easy gathering phrase. You are just as likely to take a undeserved hit while diving tables than while diving a computer. I repeat, diving is not safe. You are in an alien environment, surrounded by fluid that will drown you, pressure that can bend you, all while using life support equipment that can fail. As a nod to Papa Bear, diving can be done safely, but sitting on your couch is far safer than diving.

So at the end of the day, if you want to dive tables and your chosen dive boat doesn't allow it, pick another dive boat. Pick another resort. Shore dive in Bonaire. Go to whine and cheez and complain about your situation. This horse is too dead to be beaten further.

Frank

PS. Your knowledge of deco theory and computer algorithms is sorely lacking if you think that recreational dive computers track N2 uptake based on square profile tables. Go study Buhlmann and Haldane and get back to us. Don't bother studying the Wikipedia answer, it's not near detailed enough.

 

[redacted]

Tarponchik -

So far none of the respondents have provided the data you seek to test your hypothesis. Why don't you determine your specific detailed data needs and post that so respondents can tell you specifically they do not have any such data.

 

[tarponchik]

You can probably come up with a million different "not if they" statements, but what is your overall point or question? You seem to just want to argue a random assortment of individual points with people.

I stand by statement, especially the word "most", indicating that there may be exceptions. BTW, using EAN is not one of the exceptions.

Well, I do not think that your statement that "Gas is the limiting factor for most divers diving a PDC. NDL's are the limiting factor for most divers diving tables" is correct, and I gave you the case when it is definetely not correct. Now let's say, just for the sake of the argument, that you are right. Then there is just one logical explanation for this. That is, that computers allow diving for longer time vs. tables because tables are more concervative than computers. Meaning, computers are less safe.

Regarding your point that " seem to just want to argue a random assortment of individual points with people" you got it wrong, my friend. I've asked for evidence that computers make diving safer, and instead people, including you, are giving me "a random assortment of individual points" on diving with computers. So, do you have any knowledge of such evidence, or do you not?

 

[tarponchik]

soo if there are stats and your so interested in proving computers are useless, why havent you got them yet?

I guess, because I am not the doc at the chamber

 

[Web Monkey]

Well, I do not think that your statement that "Gas is the limiting factor for most divers diving a PDC. NDL's are the limiting factor for most divers diving tables" is correct, and I gave you the case when it is definetely not correct. Now let's say, just for the sake of the argument, that you are right. Then there is just one logical explanation for this. That is, that computers allow diving for longer time vs. tables because tables are more concervative than computers. Meaning, computers are less safe.

Your point is nonsensical. Computers are "less safe" if you use a "less safe" computer or setting. If you use a "safer" computer or setting, then computers are "more safe".

As you increase the "conservatism" (MB level on the Uwatecs), they'll reduce your NDLs and add more stops, making them much safer than any table, if you equate lower nitrogen levels with safety.

Regarding your point that " seem to just want to argue a random assortment of individual points with people" you got it wrong, my friend. I've asked for evidence that computers make diving safer, and instead people, including you, are giving me "a random assortment of individual points" on diving with computers. So, do you have any knowledge of such evidence, or do you not?

Here's a "safety point". A vacation diver goes for a dive and hasn't got a clue about dive planning. Is he safer with a box that says "Go up, you're out of time" or a plastic sheet full of numbers that he hasn't been able to work since OW class 5 years ago?

Terry

 

[tarponchik]

Since a computer is only giving you theoretical answers, it could, at best, only prevent a theoretical accident.

Thanks! I understand what you are saying except I think proper words here IMHO would be not "theoretical" but "probability" and "likelyhood of accident." Would you agree?

 

[tarponchik]

What he's referring to I believe is that the attendants and doctor at the chamber can review the dive profile in the computer to determine if the diver exceeded safe ascent rates, went too deep, etc.

When one of my dive buddies went to the chamber here on Catalina several years ago, I had already reviewed her computer and thought she was fine based on the recorded dive profile. She thought she had ascended too fast. The doctor at the chamber also reviewed her computer and said her profile was well within parameters considered safe and she was released.

You mean, she went to the doc w/o having any synptoms? I am sorry I forgot why I decided you are a tech diver:depressed:

 

[tarponchik]

Every time someone comes out with an answer to your question, you change the question. Every time someone qualifies their answer, you qualify the question.

You are confused, Frank. There were very few people who gave answer to my question (please read the original post again, in case you forgot what the question was). People (you too) just say what they have to say, and this is not necessary answering my question. Sometimes I reply to this side topicks, sometimes I ignore them, but this is my choice. With all due respect, Frank, please limit your commands to your boat crew.

Let me put it straight. No-one has published data that says diving computers is any safer than diving tables. There is no compiled data available to support such a study if someone wanted to perform one.

Bingo! Thank you very much, Frank for your direct and honest answer.

you think that recreational dive computers track N2 uptake based on square profile tables.

I never said I do.

 

[tarponchik]

Your point is nonsensical. Computers are "less safe" if you use a "less safe" computer or setting. If you use a "safer" computer or setting, then computers are "more safe".
Terry

But if computer is tuned to "safer" settings then the diver will be also limited by NDL, not air, right?

My understanding of the statement was the following. Imagine 2 divers that dive together the same profile +/-3 feet. One planned it with tables, one is usung comp. But when the table guy has to surface with 750 Psi because he is limited by NDL, the comp guy still can stay extra time till he runs out of air. So the comp guy comes up later with 500 Psi, cause his comp says he can stay till he runs out of air. However, since they did the same profile, I say that either the table guy was too concervative, or the comp guy was taking his chances. If, however, the comp guy changes his settings to be more concervative, then he also will be limited by NDL, not by air, which will make the original statement erroneous.