Bendy computers

[John Gulliver]

Re computers vs tables, the following posting by John Bantin on Diverent last May puts the case well, in my opinion:
"No computer manufacturer will guarantee that its product will stop you getting a DCI incident.
However, I believe it is very wrong to say that using a rough table is more safe than using a computer with an algorithm designed to match the sort of diving you are doing.
I have done as many dives as almost anyone. I have dived deeper than it is now recommended to dive using air. I have done six (6) dives a day for periods of up to five days on several ocasions. I have done three and four dives per day for a non-stop period of 20 weeks while dive-guiding. And I have done this now for 22 years and always with the guidance from an in-water diving computer.
In fact, have used a diving computer since the time when other divers used to try to physically tear it off my wrist because they thought it was dangerous. I now use a minimum of two because if I have a failure I do not want to have to stop diving for 24 hours. (I usually use three.)
I may get a DCI tomorrow. However, I have recently had the retinas of my eyes examined for damage and, contrary to expectations, NONE has been found so I have not had a DCI incident yet. I believe that the correct use of the right diving computer has been the single most important contribution to my diving safety.
Computer manufacturers are striving to make them even safer (eg. Suunto RGBM, Uwatec Smart and others).
If you pre-plan your dive using a PC you are using a computer but simply foregoing the opportunity to make changes during the dive. This is all very well if you have the discipline to stick to a strict regime but that is usually out of the question on most leisure-dives (world-wide) because, how can you plan for the effects of an up-current or down-current?
I never had the advantage of youth because I started diving only when I was 33.
I am now an old diver. I never was a bold diver. I am certainly not superman when it comes to fitness.
Use your computer(s) and understand the significance of the information displayed. Understand the concept of continuous decompression. Have perfect control of your buoyancy and always ascend slowly especially through that last couple of metres. Never kid yourself that diving can be without risk."

[MATTBIN]

Hmm, I wonder. I like JB's attitude etc and I know how JG dives so I dont want to upset either, BUT.. just because JB hasnt got bent (yet - and hopefully never) doesnt mean any one of us wont, we all have different physiology. However the point being made I suppose is not to trust the computers to be spot-on and just intepret the info and make a judgement call. Am I correct in saying that JB dives mainly warm water, could that be a factor. I am surprised that he hasnt been damaged in some way as statistically the deep dives combined with multi dives and multi days are the ones likely to result in a bend.
Matt

[John Gulliver]

JB dives anywhere and everywhere, on average 30 hours a month. He can probably more than match anybody on this forum or Divernet as regards experience, training and diving in varying conditions, with every possible kind of equipment.
The basic point is that a dive computer is in principle no different from any other computer - it just gives you a heap of information,which you can choose to ignore or use as you wish. It's up to you to use it intelligently. It doesn't mean that you can forget all the fundamental rules that you've learnt, though.

[Andy Winterburn]

I read the post from Peter K with sympathy and read it again carefully to learn.
I also recall reading on a number of occasions and from a number of sources, that to plan a dive and dive that plan, with or without a computer does NOT mean that you are immune from a DCS hit.
Perhaps people, and Peter and the guts to say it himself, become complacent, perhaps the computer didn't provide the 'perfect' profile. On the other hand the march over the hills could have done the damage.
A friend of mine climbed down to Dotty dived the same profile, stops and all as the others in his party. He got the DCI hit and the chamber others did not.
The thing to learn here is 'There but for the grace of god go I' and modify our practices. That is until we forget again.

[darthmoll]

Still no answer from ann marie, wot a surprise, what is it they say about empty vessels?

[Stephen H]

Show me a dive profile on a computer and I'll show you a table that says you 'missed' stops on that dive. It's just the nature of computers v tables. A table will always assume that you descended directly to the maximum depth at the recommended rate, stayed there for the entire duration of the bottom time and then ascended directly to the surface or first stop, again at the correct rate. Even on intact wreck on a perfectly horizontal bottom there will be some time spent shallower than the max depth that the computer will allow for but a table will not.

The point is that millions of dives have been done on computers and AFAIK no-one has ever succesfully sue a manufacturer for product liability after a bend.

FWIW I was bored one day 10 or so years ago so I gathered up the incidents reports for the previous 6 years or so and compared the number of bends. This covered the period when computers became much more affordable and reliable after the Decobrains and Edges. There WAS an increase in the number of bends over the period but it wasn't a huge jump. The increase wasn't significant enough for one single contributory factor to be suggested.

I daresay bends have increased threefold since the mid eighties but since there are many more divers doing lots more dives deeper and longer it is difficult to say whether or not the actual rate has increased or simply the overall number of bends.

(Edited by Stephen H at 9:52 am on Jan. 26, 2003)