Are dive computers making bad divers?

[Celt]

That's an interesting idea. One minor downside I discovered diving with two computers on a liveaboard is that it meant one more buckle to do and undo five times a day. It's the kind of thing that makes it very tempting to just start leaving the second one behind, because what are the odds. But then if you end up needing it, it won't have all your previous dive info. If computers came in pairs as a rule, I imagine they might come in some type of bracket to either strap them both on your wrist side by side with one strap, or to have them on two sides of the same console.

I'm a little skeptical that divers in the analog days were as attentive to their instruments and tables as some claim or imply. It would be interesting to travel back in time and secretly attach some computers to their gear, then compare the data with their logs.

We didn't watch anything, I dived a 72 with no depth gauge, no timer and no spg, when you ran out of air you pulled the reserve and surface slower than your smallest exhaust bubbles.

 

[Esprise Me]

You can strap a spare PDC to a harness or keep it in a BC pocket for most NDL liveaboard diving. The backup is there in case one dies so you don't have to wait 24 hours to dive again — a rule that most liveaboards enforce when your only computer fails.

Of course having them both in view and easily compared is a good idea for more advanced technical dives, which argues in favor of identical PDCs or at least identical algorithms.

True, although few rec computers these days have exactly the same algorithm unless they're the same brand. My two computers each had at least a turn or two giving me the more conservative reading. At first I followed both; eventually I said the heck with it and just followed the one that was usually more liberal. Fortunately the other one wasn't the type to lock me out for going into deco.

 

[wetb4igetinthewater]

That's an interesting idea. One minor downside I discovered diving with two computers on a liveaboard is that it meant one more buckle to do and undo five times a day.

No bungee mount? That to me is a God send.

 

[Esprise Me]

No bungee mount? That to me is a God send.

Thought about it; I like the one on my compass. But it doesn't work as well if you're switching from drysuit to wetsuit to bare skin (e.g. to wear it as a watch, which I like to do with my Teric on dive trips. The Cressi I might have put on a bungee if I could get the dang straps off.) Then again, a pair of dive computers might look too dorky to wear as a watch, anyway.

 

[Celt]

But could a modern computer cause a poor decision by presenting to much information, it's a lot easier to make a quick decision when you don't have to think about all the information a computer is displaying.

 

[Esprise Me]

What information might be too distracting, and what sort of poor decision might that lead to? It makes sense; I just can't come up with any specifics.

 

[Belzelbub]

But could a modern computer cause a poor decision by presenting to much information, it's a lot easier to make a quick decision when you don't have to think about all the information a computer is displaying.

Absolutely. Too much information, or information presented in a confusing or unclear manner can lead to a poor decision. Part of that can be the fault of the diver, as many don’t seem to know what their computer is telling them. Part of that can also be on the manufacturer for designing a confusing interface.

Even if a diver confuses temperature for depth, the computer will still track what’s happening, but it’s up to the diver to understand what it’s trying to tell them. I think re computers can be especially problematic, as it’s unlikely that the diver is familiar enough with it to be able to quickly understand what is on the display.

 

[dmaziuk]

True, although few rec computers these days have exactly the same algorithm unless they're the same brand. My two computers each had at least a turn or two giving me the more conservative reading. At first I followed both; eventually I said the heck with it and just followed the one that was usually more liberal. Fortunately the other one wasn't the type to lock me out for going into deco.

Can easily be the case with exactly the same algorithm but different sampling and/or recalculation rates, too.

 

[Wibble]

I wanted to make this response separately.

In an earlier post, I gave dive details of a 2-tank dive I did last week. I will repeat the challenge here: explain to me how you and your boys would handle the planning for this 2-tank dive using EANx 32:

Dive One: 103 feet for 81 minutes
Surface Interval: 1:15
Dive #2: 82 feet for 88 minutes

Interesting challenge for rules of thumb and approximation…

103ft is 31m. At 30m it’s 30 mins on 32%, thereafter it’s 1;1 for decompression. 81-30 ~= 50, so 30+25=55mins on the bottom and 25 mins of accelerated deco.

Second dive’s shallower but there’s the short surface interval. Would plan for roughly the same timings on the second dive, 55mins bottom and 25 to 30 mins of decompression.

But I’d check it in MultiDeco and would follow the computer's TTS calculations.

Bzzzzz whrrrrrr….MultiDeco says that estimate isn’t a million miles out using 50% as the deco gas. Estimate errs on the side of caution.

 

[BlueTrin]

Interesting challenge for rules of thumb and approximation…

103ft is 31m. At 30m it’s 30 mins on 32%, thereafter it’s 1;1 for decompression. 81-30 ~= 50, so 30+25=55mins on the bottom and 25 mins of accelerated deco.

Second dive’s shallower but there’s the short surface interval. Would plan for roughly the same timings on the second dive, 55mins bottom and 25 to 30 mins of decompression.

But I’d check it in MultiDeco and would follow the computer's TTS calculations.

Bzzzzz whrrrrrr….MultiDeco says that estimate isn’t a million miles out using 50% as the deco gas. Estimate errs on the side of caution.

What are the rules of thumbs you used in the first paragraph?

Where are the 81 and 25 coming from?