Dive Computer advice please

[scubadada]

As per the post by @dmaziuk It is my impression that dive computers will only lock you out if you fail to clear a mandatory decompression stop. There is no acceptable excuse to not recognize that your computer has gone into deco and then to clear the short deco obligation it has given you. This is like "accidentally" running out of gas because you did not pay any attention.

 

[Lorenzoid]

Would not knowingly purchase a dive computer that "locks out" for violating it's expressed "limits".

To each his own. I think whether the lockout, uh, feature is something to avoid like the plague or nothing to be concerned about depends on the kind of diving one does. A conservative diver, maybe an older person, who limits their dive time and depth and does only a couple of dives per day may never get close to NDL. I've gotten more conservative as I've gotten older, and my roughly 1-hour 60-70 ft max, multi-level reef dives generally leave me nowhere near NDL. I have a Shearwater, but for that kind of diving I could use any computer.

 

[dmaziuk]

I've gotten close to NDLs and over them, and somehow I never managed to get my computer into deco violation lock-out. One just has to Read The Fine Manual and pay attention.

Up to a point, obviously: I am told one can plan a "technical" deco dive in Suunto DM5 and dive it with a Zoop, but I wouldn't expect that to be the best tool for the job.

 

[Belzelbub]

To me, it’s the principle of the lockout and what happens after that bothers me. I have purchased computers in the past that would lockout. I’ve never locked them out. However, going forward I won’t buy any computers where I can’t at least turn off the lockout.

After a lockout, the computer continues to function in gauge mode. It will still display depth and time. No purpose in doing that if there is supposed to be no more diving. It just doesn’t keep a record of the dive and additional tissue loading is unknown. A computer that doesn’t lockout will continue to log and track tissue loading, and provide information to the diver.

Basically, the lockout is ineffective. The divers who would benefit most from the lockout are those that either don’t monitor or don’t understand their computer. And, they may continue to dive anyway.

But, it’s all irrelevant. If you want a computer that will lockout, there are plenty of options. If you want one that won’t, there are options there as well.

 

[admikar]

Would not knowingly purchase a dive computer that "locks out" for violating it's expressed "limits".

Lock out computers are usually cheaper. Guess what is main driving factor for people that can't be bothered to read the manual or take extra diving education?

 

[Bloody Marvelous]

To be clear, I'm not a proponent of what I'm about to describe, but it is what is recommended by many agencies:

You can dive Nitrox on an Air profile, and go into "deco". Knowing that you've got a massive safety margin and ignoring the deco obligations can be argued to be a totally valid way of ending the dive. In that case there is no reason to lockout the diver as he's well within the real NDL, he just exceeded what the computer was telling him.

Again, not a proponent of feeding your computer garbage information, and then not following what the computer is telling you. If you're diving Nitrox, set the correct percentages. If you want to give yourself a safety buffer, don't ride the NDL.

 

[Angelo Farina]

For me, every dive is a deco dive. This was the case when using tables, my planned dive was always the first on the table for the chosen depth which mandated for a short deco stop.
Same with a computer now, I always plan to EXCEED slightly the NDL..
I gather the proper resources (logistics, gas, redundancy, equipment, training, etc.) for dealing with a mandatory deco stop.
Then, if something happens forcing me to shorten the dive (getting cold, for example) I will end up within the NDL.
But that is the unplanned case.
If everything runs as planned, I will do my llanned deco stop before surfacing, and doing so the computer does NOT lock me out, as doing planned deco stops is just normal rec diving in most of the world.
Of course, if I miss the mandatory deco stops the computer locks, telling me to avoid further diving for 24h, which I think is correct, as this means that my body went in an extraordinary and dangerous condition.

 

[rongoodman]

To be clear, I'm not a proponent of what I'm about to describe, but it is what is recommended by many agencies:

You can dive Nitrox on an Air profile, and go into "deco". Knowing that you've got a massive safety margin and ignoring the deco obligations can be argued to be a totally valid way of ending the dive. In that case there is no reason to lockout the diver as he's well within the real NDL, he just exceeded what the computer was telling him.

The only time I ever had a missed deco message was on a Shearwater being used as a backup which I hadn't set up properly to track my rebreather. It was quite unhappy with me, but after I realized my mistake and cleared the error message it continued to function, as it should have.

 

[admikar]

Of course, if I miss the mandatory deco stops the computer locks, telling me to avoid further diving for 24h, which I think is correct, as this means that my body went in an extraordinary and dangerous condition.

That's all relative.
All these computers will lock you out, regardless of how much deco you missed.
Why would you be in danger if a computer with GF of 20/60 locks you out for 1 minute of skipped deco? While you could be clear doing the same dive on GF 30/70, hell you could even be NDL the whole dive.
I prefer to make my own decisions regarding my safety.

 

[Lorenzoid]

That's all relative.
All these computers will lock you out, regardless of how much deco you missed.
Why would you be in danger if a computer with GF of 20/60 locks you out for 1 minute of skipped deco? While you could be clear doing the same dive on GF 30/70, hell you could even be NDL the whole dive.
I prefer to make my own decisions regarding my safety.

What ARE the GFs used by computers that have a lockout feature? Some aren't Buhlmann, so who knows. Regardless, these computers generally allow a diver to set a conservatism level. If a diver sets conservatism to high and then does not dive so conservatively and messes up a deco stop and gets locked out, I would say that should be no surprise to the diver. That diver has made their own decision regarding their safety, just as you do with a computer not having a lockout feature.