Computers that don't lock out tangent.

[Ghost95]

Morning all, I didn't want to hijack the thread of someone looking for computers that don't lock you out, but I have a question.

Why and to what type of diving would that be important?

It seems if you omit a deco stop the computer model would become invalid for further diving right?

 

[NAM001]

Those that do RD. Ratio Deco. The RD stops may not match with the computer generatied stops as far as either depth or time goes. RD may say 2 min at 60,50,40,30,20 and 5 min at 10. The computer may say 5 min at 40 8 min at 20 6 min at 10. Following RD will violate the computer recommendations. Violate the puter and it locks out when you miss or cut short a stop.

Now have your computer in high conservative mode. you do a 100 ft dive and over stay the calculated NDL of say 10 minutes. You know that if you had set the conservatism for low you would not be in a deco condition , so you go up with out stopping. This can also easily happen if you dive two computers and the conservatism are set differently and you did not catch it until too late. You surface one puter is ready to go again and the other is locked up.

 

[Ghost95]

Thanks for the reply. If you're running an RD dive plan, then you're using the computer more as a timer I guess?

I guess the tech side, which I don't know much about, might use it but on the rec side I'm still not sure I see the reason. Just interested though.

Thanks.

 

[tbone1004]

Morning all, I didn't want to hijack the thread of someone looking for computers that don't lock you out, but I have a question.

Why and to what type of diving would that be important?

It seems if you omit a deco stop the computer model would become invalid for further diving right?

violating a deco stop doesn't make the computer model invalid. With the Shearwater computers and others, it just tracks the tissue levels as normal. Depending on the violation, getting back in the water may be better for you than not.

In teaching scenarios it is critical to not have a computer that locks out on you from a student safety perspective. If a student screws up and shoots to the surface, certain computers can/will lock you out for rapid ascent, skipped safety stop etc, but you still have students on the bottom and need to bring them up safely.

 

[Jonn]

If you’re close to NDL with a class of unqualified students, surface rapidly to assist one student, and go back down to deal with the rest, you’re unambiguously violating the limits and ‘deserve’ a deco hit, right? That’s no good! That’s why your computer is locked up in the first place; your physiology has no ‘educational exemption’ and the model of it in the computer doesn’t either. What would your agency and insurance have to say about that?!

 

[tbone1004]

If you’re close to NDL with a class of unqualified students, surface rapidly to assist one student, and go back down to deal with the rest, you’re unambiguously violating the limits and ‘deserve’ a deco hit, right? That’s no good! That’s why your computer is locked up in the first place; your physiology has no ‘educational exemption’ and the model of it in the computer doesn’t either. What would your agency and insurance have to say about that?!

please read up on the physiology that is going on with this and the reasons that computers will lock out. Blowing safety stops counts with some, having too rapid of an ascent counts, neither of which mean you actually hit NDL. I'm sure my agency and insurance companies would much rather have me chase the student who bolted and prevent him from embolizing then go back down to get the rest of the students than letting one embolize or having students at the bottom who have to make an unsupervised ascent. All of those are far worse, but more importantly by going back down with a computer that is actively tracking your tissue loading, it will give you an ascent profile that is unlikely to leave you with an underserved hit since you went back down and made an appropriate ascent.

@Duke Dive Medicine care to weigh in?

 

[Jonn]

You’re right about my ignorance of the underlying mechanics of decompression. I vaguely understand gas precipitation out of liquid, I can see it when I open a bottle of pop, but I’m hardly going to write my own algorithm! That’s just the point: I mostly treat the computer like a black box and trust it to keep me safe, so I follow it’s instructions unless I have a very good reason not to.

There are emergencies where I might make the choice to put my health at risk and ignore the computer. There are situations where taking those sorts of risks is appropriate, where playing the hero is the right thing to do. Those would be emergencies though! After solving them, if I survive, my diving would certainly be done for the day and I would take care to not encounter the same situation in the future. You seem to be taking this hobson’s choice “if a runaway trolly would you switch the tracks” situation as routine enough that you’re buying equipment specifically to handle it gracefully, like nothing happened at all.

Your computer doesn’t know or care about other divers who might or might not be embolizing or otherwise need your help, it’s only there for you. Perhaps you should you have another competent diver ready to handle these ‘routine emergencies’? Are you sure you’re not becoming complacent about all this?

 

[tbone1004]

[QUOTE="Jonn, post: 8745856, member: 476593"Perhaps you should you have another competent diver ready to handle these ‘routine emergencies’? Are you sure you’re not becoming complacent about all this?[/QUOTE]

yes, it has never actually happened to me because I don't let the situation get to that point. That said, it can happen, I've seen it happen to others, and I've solved that problem for others. It's not something I'm willing to risk and prefer to buy computers that don't do stupid things and since it is standard with all technical computers to not lock you out and those technical computers are also the best recreational computers, I'm not going out of my way to get it. That said, it is also much more dangerous to have the lockout as there are many reports of divers getting locked out and then ignoring it and diving anyway. Much better to have a computer that is tracking everything and trying to keep you safe versus one that says "tough luck, if you want to dive again I'm not going to do anything for you other than count depth and time, hope you don't die"

 

[NAM001]

Thanks for the reply. If you're running an RD dive plan, then you're using the computer more as a timer I guess?

I guess the tech side, which I don't know much about, might use it but on the rec side I'm still not sure I see the reason. Just interested though.

Thanks.

you should be but there are those that do not for various reasons.

 

[Duke Dive Medicine]

please read up on the physiology that is going on with this and the reasons that computers will lock out. Blowing safety stops counts with some, having too rapid of an ascent counts, neither of which mean you actually hit NDL. I'm sure my agency and insurance companies would much rather have me chase the student who bolted and prevent him from embolizing then go back down to get the rest of the students than letting one embolize or having students at the bottom who have to make an unsupervised ascent. All of those are far worse, but more importantly by going back down with a computer that is actively tracking your tissue loading, it will give you an ascent profile that is unlikely to leave you with an underserved hit since you went back down and made an appropriate ascent.

@Duke Dive Medicine care to weigh in?

Your explanation makes sense to me.

Best regards,
DDM