Incident due to battery change on dive computer

[Pedro Burrito]

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A ScubaBoard Staff Message...

Moved from A&I to Near Misses and Lessons Learned.

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[Abdullah]

Yes, but by playing with some factors, I did manage to get it to be just over 5 minutes of deco at 10 feet. That is basically a safety stop. Of course the factors were an EXTREMELY aggressive ascent. Something I would never even think to do unless a dire emergency. A 5 minute dive to 95 feet followed by a slow, gradual rise could be done without deco. But staying at 70 feet for that length of time and not putting in any stops is just nuts, regardless of what a computer tells you.

I got V-Planner down to 4 minutes at 3 m after his SS. But all of the tables and software in the world are useless if you won't comply anyway.

The lesson here is to believe your indications. The method the OP chose to manage his dive was a PDC. The PDC was indicating that his NDL time was ending, but chose to ignore it because he'd done the dive before. The PDC indicated deco was required and the OP rationalized that he knew more than the PDC and ignored it. His PDC locked out because he blew his deco and he chose to ignore that too (nanny state PDC's lock out to protect you from yourself).

If a PDC is how the dive will be managed, then believe what it is indicating during the dive. Any discrepancies can be sorted once back on the boat, after you've cleared your deco obligation.

 

[MMM]

Well no, but I have on occasion forgotten to change one of my computers to nitrox for my second dive. I will look at one and think "that's doesn't seem right". Then I will look at the other and remember....oh yeah, I forgot to change your buddy. Same idea as what happened here. It is a kind of fail-safe and at the worst, I finish the dive on air profiles instead of nitrox.

But there was no failure of the device in regard to proper function.

I once was carrying a spare pdc in my pocket on a dive. Upon surfacing, it became apparent I had bent it by 1 minute. Other computer said all was well....

 

[AfterDark]

Except for shore diving I have never done a dive in Cozumel that the Padi tables would not have had me in decompression. I have never been in decompression by my computer. I have never known myself to have DCS. I suspect there are a lot like me. Kind of makes the tables look foolish in the computer age.

That is until the computer gets left home or it malfunctions and you can't dive without it. I carry a second mask, knife, redundant air, computer and plastic tables.

Not being prepared is foolish during any age.

 

[RJP]

Except for shore diving I have never done a dive in Cozumel that the Padi tables would not have had me in decompression. I have never been in decompression by my computer. I have never known myself to have DCS. I suspect there are a lot like me. Kind of makes the tables look foolish in the computer age.

Kind of makes someone who doesn't understand why tables wouldn't be the right tool to plan a multilevel dive in Cozumel look foolish.

 

[Rich Keller]

What is not on topic is arguing why not teaching tables in modern computer instruction is wrong. This is an accident and incident forum. Any discussion needs to be directly related to the specific incident that spawned this discussion.

Isn't the main point of these discussions to learn from other peoples mistakes so it doesn't happen again? What I learned is that the OPs plan B if his computer failed was to just keep going and hope for the best. I think knowing how to use the tables in this instance is a much better plan B and therefore a valid part of this discussion. I apologize to the OP for giving him a hard time about not using the tables IF he was never taught how to use them in the first place. It never occurred to me that OW training standards had dropped so low as to exclude basic survival skills.

 

[KeithG]

Isn't the main point of these discussions to learn from other peoples mistakes so it doesn't happen again? What I learned is that the OPs plan B if his computer failed was to just keep going and hope for the best. I think knowing how to use the tables in this instance is a much better plan B and therefore a valid part of this discussion. I apologize to the OP for giving him a hard time about not using the tables IF he was never taught how to use them in the first place. It never occurred to me that OW training standards had dropped so low as to exclude basic survival skills.

but there was no computer failure. so no need for any type of backup (computer or tables). so stop mentioning tables! or backup computers! the real topic is ignoring the available information.

the first failure was ignoring his instruments. and then a second failure occurred when he got back in the water after he knew he had a violation on the first dive. i would consider both of these as serious judgment errors.

no equipment failures occurred. only human decision failures.

the OP simply decided to ignore his instruments because he thought he knew better because he had "done this dive before".

 

[Charles2]

I was not happy with my decision to dive without a properly working computer and also very unhappy to find that a Dive Master certified diver would do the same. Lost quite a bit of sleep that night and decided that was never going to happen again.

Sooner or later, everyone winds up at a significant decision point that reinforces lessons that we already knew. I'm just glad that you finally got to yours, that you were lucky enough to be unharmed (or worse), have learned enough to modify your future behavior, and have the guts to post about it here.

Be safe out there.

 

[boulderjohn]

Isn't the main point of these discussions to learn from other peoples mistakes so it doesn't happen again? What I learned is that the OPs plan B if his computer failed was to just keep going and hope for the best. I think knowing how to use the tables in this instance is a much better plan B and therefore a valid part of this discussion. I apologize to the OP for giving him a hard time about not using the tables IF he was never taught how to use them in the first place. It never occurred to me that OW training standards had dropped so low as to exclude basic survival skills.

Have you read the thread?

The computer did not fail at all. The diver did not use it properly.

When students are taught in their courses to use computers, they are taught how to plan with them. They are taught how to use them to stay within decompression limits. They are taught how to use them to guide their ascents. They are taught how to follow the computer guidance in case they accidentally go into decompression. The diver did none of the above--not one.

They are also taught what to do if the computer fails, but in this case the computer did not fail.

Is it your contention that if he had been taught how to use the tables, he would have known how to use the computer properly?

 

[Wookie]

Have you read the thread?

The computer did not fail at all. The diver did not use it properly.

When students are taught in their courses to use computers, they are taught how to plan with them. They are taught how to use them to stay within decompression limits. They are taught how to use them to guide their ascents. They are taught how to follow the computer guidance in case they accidentally go into decompression. The diver did none of the above--not one.

They are also taught what to do if the computer fails, but in this case the computer did not fail.

Is it your contention that if he had been taught how to use the tables, he would have known how to use the computer properly?

John has nailed this. I see this on the boat with recreational divers often. They know we offer 5 dives a day. They know most make 5 dives a day. They know that if others do it safely, they should be able to also, so when they forget to set the O2 percent for the first dive, they know they are safe even though their computer is screaming at them, as it has defaulted to 50% O2 and 79% N2. They get all bent out of shape when they come up with a bent computer, and we make them sit out until their computer unbends. Or if they can go on tables, which is impossible after dive 2.

What they don't know is that most computers are O2 limited by dive 3 on day 2 if they have been diving nitrox, and their computer doesn't actually have an O2 algorithm, but a O2 counter, like most recreational computers do. They don't know that many divers on recreational computers will take it easy on the second day, maybe not diving the bottom of the reef and staying near the mooring. They don't know these things because their training failed them.

It doesn't matter what training they got, pick any of the alphabet soup of agencies, it doesn't matter. I don't expect, nor do I think it is reasonable to expect a PADI or SDI instructor teaching a computer OW course to know how every computer works, and for those who got taught back in the table days, anyone with $400-$1200 in their pocket can walk into any dive sop, or better yet, log on to LeisurePro or Scubadotcom and buy whatever computer they can afford. They have been told that computers "let them dive longer than tables", so the "computer will keep you safe". Don't get me wrong, computers will give you more bottom time than a set of dive tables for 99% of recreational dives, and I don't cut tables for the vast majority of the diving I do, but the trick is to understand what the computer is telling you.

The only way to understand that is to get trained on the computer. Now, you can go to your instructor, shop owner where you bought the thing, or read the manual and comprehend on your own, but it isn't the same as driving the car. When driving the car, it isn't critical or even desirable to understand how an internal combustion engine works. It helps if the car doesn't start, knowing that you're missing either fuel, spark, or compression, but as long as you're cruising down the interstate at 73, knowing how it's all working doesn't matter. Not so with a dive computer, and I think this thread is a perfect example of that. The OP doesn't understand conservatism. He just knows that if he sets his computer for most conservative, he has a shorter allowable bottom time than if it's set for least conservative. Since he wants the max bottom time he can get, he sets it for least conservative, because it will keep him safe, right? He also knows that if his computer craps out, or locks up, it wasn't really his fault, so as long as someone else has a computer, he'll be fine.

This shows a gross conceptual error on what a computer does, how it works, and how it helps the diver make informed decisions about his dive. If he hasn't gotten those simple concepts down, what makes anyone here think he can figure out what the tables or v-planner or any other decompression tool will be helpful to him in planning and executing his dives? This is obviously the holiday diver who makes dives at the expense of safety, not through malice or a lack of caring, but a lack of understanding of what he is doing to his body. He's the same guy who tells his wife not to worry her pretty little head, because his OW instructor drummed it into his head back in OW class: Diving is safe. And because diving is safe, he hasn't made proper preparations for his family in the event the worst happens to him, because what could possibly go wrong?

Am I being a little harsh? I reckon I am, because this is what I see the training agencies making diving. I see very little to no decompression theory taught until Divemaster/Divecon. I'm betting if we asked out OP what a tissue compartment is, how many his dive computer algorithm considers, and which are fast or slow, we'd get the chicken look back. While those questions aren't relevant to OW diving, they were taught back in the day, along with Boyle, Henry, Charles and Dalton. Now, 20 years later, I couldn't tell you which law was which, but I could give a pretty good explanation about goats, caisson workers, 20 year old hardbody navy divers, and why you don't dive following a computer violation.

This should be knowledge we are born with. Sadly, we've removed Darwin's theory from the equation.