Dive Computer No Deco Computations Question

[JMarc]

We are in Basic Scuba, guys. Perhaps you should not be inventing extreme scenarios to try and prove a point. The underlying issue here is whether a Suunto locking you out during a dive is a good idea or not. Do you think it is?

I'm someone who deals in trade-off and not absolute. The lock out seems a sensible option depending on the circumstances. And the more you insist on simple options because we are in Basic Scuba, the more sensible it looks along with the user guide instructions of going to 5 meters and empty your tank.

 

[Bento.Box]

We are in Basic Scuba, guys. Perhaps you should not be inventing extreme scenarios to try and prove a point. The underlying issue here is whether a Suunto locking you out during a dive is a good idea or not. Do you think it is?

It doesn't lock you out during a normal dive.

If you are discussing deco diving worst cases in which you are unable to reliably hold your depth, you are in advanced scuba territory, well outside what a padi aowd diver experiences and what a recreational dive computer is meant to support.

 

[tursiops]

I'm someone who deals in trade-off and not absolute. The lock out seems a sensible option depending on the circumstances. And the more you insist on simple options because we are in Basic Scuba, the more sensible it looks along with the user guide instructions of going to 5 meters and empty your tank.

Even the PADI RDP does better than that. depending on whether you exceed NDL by more or less than 5 minutes. Suunto seems to design for the least capable diver, including adding a 1% safety factor on whatever O2 pecentage you set...just in case.

 

[runsongas]

Sheesh. Well, at least you tried to help. Some people just can't be helped.

Really makes me wonder, though. Why did they buy the computers if they aren't actually going to use them? While I'm not a fan of lying to your computer by setting to Air when diving NX32, I understand why some do. However, if you then just ignore the warnings and guidance of the computer, what good is it. I just can't understand the reasoning there.

it was a way to add conservatism on old computers that were fixed algorithm/settings where they didn't have extra conservatism levels you could switch to. also seen it recommended here to divers that kept diving after discovering they had a PFO but didn't opt for surgery.

 

[JMarc]

This is really amazing advice - to me anyway

When an exceptional procedure for a deco violation does become an in water recompression therapy? The boundary is fuzzy. DCS is treatable. Drowning less so.

 

[Belzelbub]

It was once a very common practice. People with the necessary credentials to be published in scuba magazines recommended diving with nitrox but using air tables/computer settings for many, many years. It never made sense to me, but they were the respected scuba authorities. Go back through enough ScubaBoard discussions and you will see it argued many times.

Yeah. I’m clear that many do that. I’m not a fan of the practice of using air settings while diving Nitrox, but I do get why some do. As long as you don’t exceed MOD, it provides a safety buffer. Though that buffer may be purely theoretical.

What I can’t wrap my head around is people who do that, then proceed to ignore the warnings/alerts on the computer.

 

[tursiops]

It doesn't lock you out during a normal dive.

Of course not.....why should it? The point is that exceeding your NDL is not a normal dive, and vacation divers do it all too frequently, sometimes without even knowing it, especially if they are diving a conservative computer and following someone with a less conservative computer.

If you are discussing deco diving worst cases in which you are unable to reliably hold your depth, you are in advanced scuba territory, well outside what a padi aowd diver experiences and what a recreational dive computer is meant to support.

I am not discussing deco diving worst cases, or even deco diving by a trained deco diver; I, and the thread, are discussing NDL divers exceeding their NDL, sometimes without even knowing it, and then being clueless about what their computer is trying to tell them.

What I can’t wrap my head around is people who do that, then proceed to ignore the warnings/alerts on the computer.

But, it happens. We had a lady on a trip a few years ago who came up from her dive and said I think my computer is broken, it doesn't seem to be working right anymore. She had exceeded her NDL, ignored the DECO alerts as meaningless to her, and was concerned that now the comptuer seem to be acting strangely (i.e., it was locked out). She was NOT a brandd new diver but only dived maybe one trip every year or two.

 

[dmaziuk]

When an exceptional procedure for a deco violation does become an in water recompression therapy? The boundary is fuzzy. DCS is treatable. Drowning less so.

There are threads over in A&I and Dive Medicine about a Polish guy who didn't drown because the boat crew wouldn't let him. So he died in the chamber instead.

 

[Bento.Box]

Of course not.....why should it? The point is that exceeding your NDL is not a normal dive, and vacation divers do it all too frequently, sometimes without even knowing it, especially if they are diving a conservative computer and following someone with a less conservative computer.

It was the implication that Suunto is bad because it can lock you out during a normal dive where you stay inside your dive envelope.
This is clearly not the case. And I'm happy about that, otherwise I would have thought about replacing my Suuntos.

You can not not know that you exceeded NDL because your computer tells you so.
Following someone under violation of your dive rules is a conscious decision, for which a diver accepts the risk when doing so.
There is a "what happens if we get separated" part in the dive briefing for a reason.

I am not discussing deco diving worst cases, or even deco diving by a trained deco diver; I, and the thread, are discussing NDL divers exceeding their NDL, sometimes without even knowing it, and then being clueless about what their computer is trying to tell them.

But Suunto dive computers are very clear about what they are telling you.

But, it happens. We had a lady on a trip a few years ago who came up from her dive and said I think my computer is broken, it doesn't seem to be working right anymore. She had exceeded her NDL, ignored the DECO alerts as meaningless to her, and was concerned that now the comptuer seem to be acting strangely (i.e., it was locked out). She was NOT a brandd new diver but only dived maybe one trip every year or two.

But if she disregards her dive computer because she doesn't care, then it also doesn't matter what it shows. It's not better or worse for her if she completely took it off, if it showed error or if it tried to impose some "educated guess" on how to potentially fix a deco violation.

The scenario in discussion was a very specific one, in which the diver is unable (not unwilling!) to maintain bottom AND ceiling limits and expects a problem resolution for an extended (!) deco violation from their dive computer either as a supplement or authoritative input on how to proceed.
And this is simply an unlikely scenario and it requires advanced scuba medical knowledge and risk management to find the optimal procedure.

 

[boulderjohn]

Yeah. I’m clear that many do that. I’m not a fan of the practice of using air settings while diving Nitrox, but I do get why some do. As long as you don’t exceed MOD, it provides a safety buffer. Though that buffer may be purely theoretical.

What I can’t wrap my head around is people who do that, then proceed to ignore the warnings/alerts on the computer.

I don't know why, but for some reason the mere existence of Nitrox muddied the thinking of intelligent people. College professor Alex Brylske, editor of Dive Training magazine and author of the Encyclopedia of Recreational Diving, wrote on more than one occasion in Dive Training that when using nitrox, divers had two (and only two) choices: greater safety or greater bottom time, but not both. He said divers could either

1. use air table/computer settings in order to achieve greater safety in terms of DCS, thus not extending dive time, or
2. dive to the limit of nitrox table/computer settings to get longer bottom times, but ending up with the same nitrogen saturation as they would have by diving the limits for air.

It never seemed to occur to this obviously veery intelligent and knowledgeable man that there were options between those two. You didn't have to go so far as dive what was essentially 21%, and you weren't required to dive to the limits of the nitrox settings. According to him, if you were diving to 80 feet using EANx 36 on the PADI tables, you could either dive for 30 minutes (air limit) or 55 minutes (nitrox limit). It was not possible for some reason to do an 80 foot dive for 40 minutes.