Forgot to set computer nitrox mix, what a PIA

I was feeling great. I got on the boat, the seas were 1 ft, and I had my gear setup on my tank before we left dock. This is usually the time I set my computer and I completely forgot.

I'm doing a drift dive on Juno Ledge on a boat out of WPB. Max depth was 88ft and my average depth was 70ft. I've dove this profile many times, so I didn't freak out when I looked at my computer 25 minutes in and it said I had a deco obligation. I typically call the dive around 45-50 minutes, but opted to call the dive early (37 min) when I saw some other divers shooting their SMB. I ended the dive with 1200 psi.

On the SI, I was shocked that my computer completely locked me out. It wouldn't let me adjust anything that had to do with diving. So now it's going to just be a depth gauge and bottom timer on the 2nd dive.

I was diving solo this day, but hanging around other divers as to not be completely alone. So on the 2nd dive, I told the DM that I was going to hanging around him and surface when he does. He shows me that he has nothing but a bottom timer... My next thought was that the 2nd dive was going to be interesting . Again, it's a common profile I dive. I just planned to make it a shorter dive than usual.

My 2nd dive had a max depth of 91ft, but I averaged 68ft. I was avoiding the bottom unless I saw something cool since I had no visibility on my NDL. I'm not sure where everyone took off to, but the DM and I found ourselves together without anyone else. So we just went looking for stuff. After 35 minutes he signaled he was ready to go up. I figured it was as good a time as any so I surfaced with him. I surfaced with 1500 psi.

Anyways, back to the topic on hand, why does the computer lock you out? Why am I not able to fix the nitrox mix setting? Is it that users of the computers can't be trusted? That would be ridiculous. I would have been better served if I could have fixed the setting for the previous dive and set it up for the 2nd dive. FWIW, I'm diving with an Oceanic Geo 2. I couldn't even change the dive mode to gauge mode.

Thoughts?

got asbestos underwear?

I don't know that specific model, but usually, the computers I have used will lock you out if you fail to complete the deco obligation. So If you surfaced, "against computer advice" it will most likely lock you out.

On Suunto computers, some of them have air mode, nitrox mode and gauge mode. They will not let you change from one mode to the other unntill the "No fly" time has passed. If set in Nitrox mode and you dove 21% nitrox, usually change in gas will be allowed.

Sounds to me as if you ignored your deco obligation (pr what the comp thought you were diving) and surfaced before it got done, and "bending" your computer.

My advice... Quit being a typical Male... and RTFM! ;D

I don't think you are going to like the answers you get on this. It did what you told it to which was monitor your nitrogen loading at the settings you gave it. And it locks you out for a reason, that being that according to the specs you ignored your deco obligation. According to the settings you could be at risk so it stops you from diving. And when this happens, you don't just switch to another computer or not use a computer at all, you are supposed to be locked out and not diving. It doesn't know what the tank is set for. Just going by "this is my normal profile that works" is not a good practice and not what they teach you because you can easily be put at risk by that strategy. I don't think the point is whether it is too aggressive in locking you out because it did what is supposed to do based on the settings. You were lucky to be on a boat where they apparently don't care about your diving because some boats would have set you out on seeing your locked computer.

Imla:

I don't know that specific model, but usually, the computers I have used will lock you out if you fail to complete the deco obligation. So If you surfaced, "against computer advice" it will most likely lock you out.

On Suunto computers, some of them have air mode, nitrox mode and gauge mode. They will not let you change from one mode to the other unntill the "No fly" time has passed. If set in Nitrox mode and you dove 21% nitrox, usually change in gas will be allowed.

Sounds to me as if you ignored your deco obligation (pr what the comp thought you were diving) and surfaced before it got done, and "bending" your computer.

My advice... Quit being a typical Male... and RTFM! ;D

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Thanks. I didn't really have a deco obligation based on the profile and my nitrox mix. It was frustrating and disappointing to be locked out. Thanks for the no fly info. And I won't forget again, at least I hope not

Hi MrChen. Its true that many (most?) computers will go into a lockout mode for a critical violation such as skipping deco. Unfortunately the computer doesn't know it had the wrong mix to determine your NDL and there is no way to reset the computer to recalculate the correct NDL. That's why many people that dive two computers will choose ones with the same or very similar algorithms. Otherwise you risk violating the NDL in the more conservative computer if you are not careful and that computer will shut down for that day's diving, just as you experienced.

Lisa

Shasta_man:

You were lucky to be on a boat where they apparently don't care about your diving because some boats would have set you out on seeing your locked computer.

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I've yet to be on a boat which checks diver's computers. Besides, that, I was well within the limits they expected from the divers. They said they'd start getting worried if they didn't see divers in 1 hr, expecting nitrox divers to start their ascents no later than the 50 minute mark. This was part of their dive brief, so I was well within the profile they expected the divers at the surface. For them to tell me to sit would be nuts and would be the last time I dove their boat. Last time I checked a computer wasn't a requirement to dive. In fact, the guide didn't have a computer. This is all off topic and worthy of a 2nd thread.

Part of my frustration stems from the fact that I'm a software developer. I understand the difficulties of implementing a feature with a limited input interface, but being locked out was frustrating.

---------- Post added July 18th, 2014 at 05:52 PM ----------

rhwestfall:

got asbestos underwear?

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Because I dove without visibility on my NDL? I dove the dives conservatively in comparison and surfaced earlier than I would have otherwise. My computer still gave me bottom time and depth.

MrChen, most boats don't check computers, however most computers beep excessively when deco is omitted. If you exited the water with a computer that is screaming...I would surely check it, and make you get back in to clear your deco. Sounds like your computer went into gauge mode, which is common with recreational computers when deco is omitted.

Two things I have to ask.....

1. Forgetting to set the computer to Eanx happens..I get it. But why would you not just stay under and clear the deco?

2. If you are going to disregard the computers suggestions, why even own one?

Just be glad it wasn't the other way around. Quite a few years ago someone made the opposite mistake. He was planning to do a dive on a high percentage of nitrox and set his computer accordingly. He made a last second decision to switch to a tank with air in it, but he did not change the computer. He therefore greatly exceeded his air NDLs and got badly bent.

When I read about that, I wrote to PADI and pointed out that their BWRAF buddy check leaves out a very important piece--the instruments used to measure the dive. When people are putting their gear on before a dive, it is common that the last piece to go on is anything on the wrists, and those are easily forgotten. Changing the nitrox mix is also very easy to forget, as was true in your case. I said they needed to add that to the list. I got a very enthusiastic response saying they really liked the idea, agreed with it, and were currently working on a new acronym that included it.

It never happened.

Consequently, I added it and made my own new acronym. I teach it to my OW students, and perhaps you will find it useful in the future.

I added an I for instruments, which includes making sure you have your computer and it is set properly--BWRAIF. The mnemonic I use is Bruce Willis Ruins Another Independent Film.

Not too long ago, I made a post about my dive where I dove without a computer (the battery died) so I looked at my sons computer. I knew the maximum depth and had done the dive many times before and had a timing device. The thread got locked and i got banned for 90 days for what was determined to be promoting unsafe dive practices... I hope the OP doesn't suffer the same punishment..