History behind Dive computer error mode

[ballastbelly]

"also confuse the user, as it stands apparently people get confused between remaining NDL and ascent time, is having and extra 'in error but limping back to the surface but all bets are off' mode actually a help on average"

Yes I think limited segment display on consumer dive computers limits the amount of information & disclaimer that can be conveyed.

As is the screen is already cluttered & cryptic. A DC with a multi line text screen would be easier to use but reduce battery life. Btw thanks for all the info in the thread, good reading

 

[flots am]

Wow, that should be completely unacceptable. I'm shocked they would go into an error mode while in the water instead of trying to continue working something out, especially since you were following a deco schedule you couldn't have been wildly outside of parameters.

It sounds broken. I can't imagine a DC that intentionally wouldn't give you time, depth and pressure (if AI) while underwater, even if it couldn't calculate an ascent profile.

OTOH, that's exactly why I won't use a computer for a deco dive. I know that no matter how much brown stuff hits the fan, the printed vPlanner plan taped to my wrist slate isn't going to crash or bug-out.

After spending a lifetime as a software engineer, I would never trust my life to a single computer, built with proprietary hardware, in a supposedly-waterproof box, running on a maybe-OK battery, running unknown software. There's no chance for a sanity check.

I can read the vPlanner plan before splashing and know that 5 deco stops totaling 16 minutes is reasonable for a 130' 20 minute dive on EAN28, and that once I tape it to my slate, it's there.

If I had John's buddy's computer (or any computer, really), my first stop could have been "err" or "blank", which is difficult to perform.

flots.

 

[Hatul]

Is it really bizarre?

I don't know if the oceanic ones are helium computers, but getting a 21m ceiling on air takes some doing. Using Suunto's PC software planning an air dive to 60m for 80m or 90 minutes gets you there, alternatively a 100m dive on 10/50. The Zoop claims its depth sensor is good to 80, the Oceanic manual I looked at said it would just say "Up!!!" beyond 100m. These seem like very unlikely profiles for a recreational or light technical diver who would use these computers.

I notice that the oceanic has a violation mode #1 which is like the Suunto error mode but with 5 minutes rather than 3. Maybe the oceanic would suit the OP better.

I suggest that these are reasonable parameters of behaviour beyond the intended usage of the devices.

I used to think that a lockout after a violation was reasonable too, until one hit me. I described the details in another thread, but I was doing repetitive diving with two computers: Galileo as my primary and Suunto Vyper as a backup. After a 47 minute surface interval the Vyper severely limited my ND times and went into deco, the Galileo had unlimited ND times when I surfaced not quite completing the Suunty deco stop and after a 6 minute safety stop. The Suunto locked out for 48 hrs. I did not think this was reasonable since the surface interval penalty was overly severe. And personally would stay away from Suunto.

 

[KenGordon]

It sounds broken. I can't imagine a DC that intentionally wouldn't give you time, depth and pressure (if AI) while underwater, even if it couldn't calculate an ascent profile.

OTOH, that's exactly why I won't use a computer for a deco dive. I know that no matter how much brown stuff hits the fan, the printed vPlanner plan taped to my wrist slate isn't going to crash or bug-out.

After spending a lifetime as a software engineer, I would never trust my life to a single computer, built with proprietary hardware, in a supposedly-waterproof box, running on a maybe-OK battery, running unknown software. There's no chance for a sanity check.

I can read the vPlanner plan before splashing and know that 5 deco stops totaling 16 minutes is reasonable for a 130' 20 minute dive on EAN28, and that once I tape it to my slate, it's there.

If I had John's buddy's computer (or any computer, really), my first stop could have been "err" or "blank", which is difficult to perform.

flots.

On every multiple gas dive I do I bend a computer. It is my backup. If the primary (unbent) computer died I would still be ok as I have a slate with a plan to follow and the bent computer tells me depth and time, just like the computer in a bottom timer. I'd use a gauge mode if it had it, but being a lowly Zoop it does not.

Can you be sure V-planner will not bug out? Isn't it a single point of failure without a computer too? Recently I had a vplanner update which reset the settings from metric to imperial. This left me looking at pre-existing plans for 56m dives wondering why it thought a 20 minute dive was no stop.

I may be wrong, but I suspect Suunto have more QA effort than Vplanner's developer.

 

[flots am]

Can you be sure V-planner will not bug out? Isn't it a single point of failure without a computer too? Recently I had a vplanner update which reset the settings from metric to imperial. This left me looking at pre-existing plans for 56m dives wondering why it thought a 20 minute dive was no stop.

I may be wrong, but I suspect Suunto have more QA effort than Vplanner's developer.

The difference is that if vPlanner has a problem, it's while I'm sitting at my desk, not at 150' inside a wreck.

I can look at the plan and say "Why am I getting a 10m stop when I use feet?" or "Why does this 150' dive say I can ascend directly to the surface" and examine it more closely. It crashes, I can reboot, not crap in my drysuit.

Regardless of what Sunnto spent on anything, it's still a "trust-me" dive where you have no assurance that the machine will continue operating properly or at all. This doesn't go only for Sunnto. It's entirly possible that any software can acheive a state the designer didn't anticipate and do something wrong.

A piece of paper can't. If the plan was good sitting at my desk, it's good underwater.

flots.

 

[boulderjohn]

A piece of paper can't. If the plan was good sitting at my desk, it's good underwater.

But a bottom time, a computer in gauge mode, or a watch can fail just as easily as a computer.

I only use a watch when working with students in a pool. I keep track of how the class is progressing, and I keep track of the timed exercises. One day I was thinking that the class was going really well--we were getting through the skills well ahead of schedule. Then we got out and I glanced at the clock on the wall. At some time during the dive, my watch had stopped for a while and then started up again. It may have happened several times. All I know is that it somehow lost 10 minutes during that segment of the class. Since it was working when I looked at it, I had no way of knowing it until I compared it with the clock on the wall. That's a pretty serious malfunction on a deco dive using a written programmed ascent.

 

[flots am]

But a bottom time, a computer in gauge mode, or a watch can fail just as easily as a computer.

I only use a watch when working with students in a pool. I keep track of how the class is progressing, and I keep track of the timed exercises. One day I was thinking that the class was going really well--we were getting through the skills well ahead of schedule. Then we got out and I glanced at the clock on the wall. At some time during the dive, my watch had stopped for a while and then started up again. It may have happened several times. All I know is that it somehow lost 10 minutes during that segment of the class. Since it was working when I looked at it, I had no way of knowing it until I compared it with the clock on the wall. That's a pretty serious malfunction on a deco dive using a written programmed ascent.

Any equipment can fail, but it's a lot easier and more reliable to look at your buddy's watch than to try to guess what to do when the computer says "ERR".

 

[nimoh]

Any equipment can fail, but it's a lot easier and more reliable to look at your buddy's watch than to try to guess what to do when the computer says "ERR".

couldn't you just as easily look at your buddy's computer?

I personally don't use a computer, but I don't think they are inherently unsafe.

 

[RonR]

It seems to me that all approaches have strengths and potential failure points. Computers can leak or otherwise malfunction- however they can also measure what you actually do with considerable precision, and recalculate if something happens and the plan falls apart. Tables on a slate rely on very simple technology less subject to failure, but are comparatively inflexible. Multiple sources of information seem like a good thing. Most important is having an understanding of the issues and the ability to make knowledgeable decisions, i.e. good training.


On the Cobalt, we included a planning function that starts from your actual saturation state (dive history), and allows the diver to generate a surfacing schedule, exactly as one would with desktop software. It’s something a diver can record on a slate that is based precisely on their previous dive history. Our expectation was that anyone planning decompression diving should be 1) planning the dive and 2) recording the plan on some non-electronic analog device. The computer is still there calculating, telling you your current depth and pressure, and will tell you what is happening if you don’t follow the plan, but the plan would be primary.


At to the OP’s question, I’m not sure liability laws in the US are a full explanation for why lock-outs exist. After all, Suunto, which does have lock-outs, is a European company, and Atomic, which does not, is American. When dive computers first appeared, there was a lot of suspicion, ridicule, and even hostility. Shutting out divers who violated the computer was I suspect at least partially a marketing choice to assuage the suspicion that computers were inherently unsafe. And, in fairness, the current history of algorithm safety had yet to be established. Once you start doing something a particular way, it can be hard to change.

Ron

 

[boulderjohn]

Any equipment can fail, but it's a lot easier and more reliable to look at your buddy's watch than to try to guess what to do when the computer says "ERR".

When the computer says ERR, it still gives time and depth. If you have backup plans, as any deco diver should, you have something to go on. If your watch has just lost some time during your dive and is still running, you would have no reason to to look at your buddy's watch. You would assume yours is working fine when you look at it and just not realize you had more bottom time than you thought. Hopefully, your buddy would be on top of things and you could then try to sort out whose watch was right and whose was wrong.

You did not mention the backup plans you make (and I'm sure you do) that cover contingencies like staying 5 minutes longer than planned or going a few feet deep than planned. But what if you really had some caca on the fan and it took your buddy and you much longer than expected to begin your ascent? You should have plenty of gas because you planned for that, too, but you will be making up your profile on the fly, possibly while thoroughly narced. That's why almost all the people I dive with use one of the following approaches:

1. Paper schedule with computer as a backup, hopefully one that will not quit on you in mid dive because you did not follow it.
2. Computer with another time and depth indicator and a paper schedule as a backup.
3. Two computers for both you and your buddy--4 failures is not likely.