I posted that I execute the dive with a PDC. Didn't post I don't use a PDC just that I don't trust them. Hence the watch , depth gauge and air tables for back up. Hope your reading comprehension improves!
[sarcastic response on]
Yeah but, backing up one device with three (that all must not fail/get lost or the other two are pointless plus one of which is also still electronic), is not helping things.
To return the jibe, I hope your reasoning process improves!
[/sarcasm off]
Because seriously, backing a dive computer with anything but a different dive computer runs into lots of problems, and does not function as much of a backup in the real world.
The most obvious is that people who dive with computers generally come to take full advantage of the multilevel aspect they provide, making a timer and depth gauge not work with tables. Very few people on typical vacation tourist dives know their dive ahead of time, and with good reason. Why not see what is interesting to see? What if the sting ray is ten feet deeper than the plan? With a table the only answer is to miss the close up view of the ray or the turtle etc. But technology has made that unecessary. Dive on a computer and the dive becomes more free form and more fun.
On top of that, it is a flaw to increase the failure points of the backup to three separate devices that all must work for anyone to be of use. It does not make for more security. I have seen more watches get lots than any other piece of gear because they have tiny pins holding the strap, and less hardy O-rings. Once someone moves into a proper dive rated watch, then they are getting into the amount of money that can easily buy a far more useful backup dive computer. Example: I have completely lost way more than twenty watches working as a guide, and I have blown out twice that many band pins. (I have only lost one dive computer.) This does not count watches flooding, because I long ago learned to treat watches as disposable because it there is no way to count on a watch after a battery change. And then add the fact that almost all dive computers are recoverable even after a battery compartment flood, and watches aren't, and well, dive watches just start to make less and less sense compared to computers.
....
Look, in the end, people should and will do what they want with their money, and vacation time. I am not telling anyone what they should do, rather I am pointing out that the reasoning that says someone should back up a computer with anything but another computer is faulty. And then, on top of that, giving some real world examples that help point out flaws with diving with tables, dive watches and depth gauges that are independent of the flaws of strict reasoning that makes them thewatch depth gauge and tables a bad idea.
People who spend thousands to travel to dive, and yet do not carry computers, backed up with backup computers are missing out on a lot of fun, usually because they have not thought it all the way through, or because they want to be 'old school'. Which is fine, just not well reasoned out, especially when someone thinks they are backing up a computer with a table.
