Well, I did screw up. That's all there is to it. And no, it's not appropriate to blame it on my computer. However, it did add to the problem.
If I wasn't using the computer at all, I'd have done my second dive at 12 minutes... Plain and simple. Instead, at the point where I turned the dive, my computer was reading "3 minutes," not "1 minute." I know the log doesn't show that, but perhaps I looked at the 'puter a few seconds before actual rock bottom. However it happened, I understood three minutes, not one.
Nonetheless, computers don't do square profiles... In other words, as I ascend, the NDL display INCREASES. My key was to never hit zero, but I did. That's what put me into deco. I saw three minutes and turned the dive, but it wasn't enough. I was already too close. I wasn't but maybe 20 feet or so from the anchor line... But getting to it, communicating with my buddy, thumbing the dive, and beginning the ascent apparently took more than a minute. Also, I was still ongassing for many feet... Which also took me past zero in my NDL.
So, mistake number one was cutting it that close. Again, that's something that I would not have done had I been diving my plan, which was 12 minutes surface-to-surface. Instead, I thought, "I'll ascend when this thing tells me it's okay and that way get a few more minutes out of my dive."
Mistake number two, which wasn't obvious until I posted that profile, was taking a whopping 10 minutes to ascend to my "safety stop." I'm not sure why I did this... I don't remember consciously thinking to slow my ascent so much. I was aiming for 30 ft/min, not 8! This second mistake was the real reason why I went into deco, I think.
So if your plan was 12, and the computer algorithm told you 12, why did you think that being at 98 16 minutes into your dive was "believing the computer"?
Well, because I wasn't 12 minutes at 100'... It was a multilevel dive. And my dumbass thought that perhaps the computer, which had been with me the entire dive, was more accurate, since it had real data to go on instead of "the plan." When it said "three minutes," and I took two, I thought I was fine. Unfortunately, that was not correct. I should have stuck to the plan.
The fact that the plan - both with and without the computer - was the same, only proves the validity of the plan, which I ignored. Instead, I went by the "real data" that was on my wrist, which promptly put me into deco.
The lesson isn't to avoid computers, IMHO... It's to dive the plan. The fact that I can create an accurate plan with or without the computer makes me wonder why I spent $400 on a computer.
And frankly, if I hadn't had the "false security" of that thing on my wrist, I'd have never tried to push it. I'd have simply been back on the surface at 12 minutes... Or I probably would have made sure I had a rock bottom of 80 feet at 20 minutes total dive time instead, or something equivalent.
IMHO the computer got your ass out of the fire.
Hm. Well, I can certainly see that point of view, but I believe that the best way to have avoided this whole shebang would have been to dive my plan.
Tell me this. what would you have done if you happened to find yourself at 98 feet 4 minutes past your planned time if you didn't have the computer to walk you through your deco?
1. I should have taken better care not to get myself into that situation.
2. Assuming the above situation, I'd have done the following: In my PADI OW class, I was taught that if I blow my tables for no more than five minutes, then I'm to ascent to 15 feet and do a deco stop for no less than 8 minutes. If I added a normal 3 minute "safety stop" of 3 minutes to the mix, then I'd have decoed for a total of 11 minutes at 15 feet... Very similar to the 12 minutes at 10 feet that my computer mandated. There's more, too... No flying for 24 hours... No diving for 6... You know, standard stuff. This is all printed right on the PADI OW tables.
That's the extent of my training. I have not been taught decompression technique yet... Another reason why I should not have blown my tables like I did. Instead, I made decisions based on the information that was given to me which was a mistake... I should have stuck to my plan.
Actually, I guess what I really want to ask is what the hell were you thinking when you decided to blow plan?
Lol... Great question. Maybe others can learn from my mistake if they just understand what I was thinking at the time. Maybe then they can recognize it and avoid it like I should have.
I was thinking, "Hey, cool... This gizmo on my wrist says that it's okay to be down here another three minutes... Maybe I can get just a couple more bubbles in. I love diving!"