Bent. I guess it really can happen to me.

[RJP]

I would have done that profile without a second thought.

There's something else going on.

As would I, and three more dives just like those two on a liveaboard trip. Maybe four more dives that day shore diving in Bonaire.

 

[TechDeep]

I'd like to reply with quotes, but there are so many responses, I'll try to answer as many questions as I can. I do appreciate all the responses.
Dive was on air.
The times quoted are total dive times, all inclusive.
Average depth of first dive was 45.5 ft. Second dive - 47.1 ft. Both were fairly square, 50 ft. dives.
No alarm whatsoever was tripped on the computer.
Algorithm used is Buhlmann-GF (ZHL16C)
There is no conservatism setting for this computer when used in REC mode, and I am intimately familiar with the manual.
The computer is a Liquivision Lynx that I have been using for 2 months, with about 30 dives logged on it.

Jim - in general I agree with what you are saying, and don't consider it finger wagging at all. I appreciate your responses, with the possible exception of me not being a diver you would dive with. I really think if you knew me and my diving practices better, you would not have an issue diving with me. No one that I have ever dove with in 20 years has ever considered me an unsafe diver. For example, you asked about a backup plan. I do carry an analog console on a hose that has a pressure gage, depth and time. I also have a dive watch that has depth as well. I think a bomb could go off, and I would still know how deep and how long. However, even with all that backup if my computer fails, (as it did last month) I abort the dive, using my backup gear.

Now, having said all of this, I am going to admit some things that are what they are. Not excuses, just practices that I have adopted that I will change from this point on....

On dives less than 60 feet, I have relied solely on my computer for NDL time. The last time I remember checking my NDL time on my last dive Saturday, it was at 12 minutes. That was when I was starting my ascent. I saw this as adequate padding at the time. Anything deeper, I plan out first. Part of this may have come from working with students so much on dives shallower than 60ft. I don't see any way of planning all those dives, and I guess I just slid into the habit of not planning these dives like I do deeper dives. Plus I've dove this wreck successfully many times.

This incident has made me feel lazy, complacent, and maybe a little bit not as smart as I thought I was. I actually feel lucky that it happened, as it has served as a wakeup call. Yes it is nice to have had 20 years of diving with only this one major incident. But the thing that goes along with 20 years of diving is that you're 20 years older than you used to be, and maybe age has more to do with DCI than I thought it did.

Anyway, I have 27 more days to think about it.....

---------- Post added September 3rd, 2013 at 11:33 PM ----------

It doesn't really matter. vPlanner is happy with that profile, with no deco and no safety stop and anything from a 10'/minute to 30'/minute ascent rate. I would have done that profile without a second thought.

There's something else going on.

flots.

Any ideas on what that could be? I was comfortable with this profile myself until I looked more closely at the tables. If something else is going on, I would sure like to figure out what it is.

 

[supergaijin]

The profile - Dive 1-55.5 ft. 42:49. Surface interval 43:55 Dive 2-55.5 ft. 44:21. Ascent rate was less than 30ft./min. on both dives, much slower on first dive. I'm getting all of this information as it was uploaded from my dive computer to my PC. I think the slow rate on the first dive was due to seeing a bunch of barracuda, and having plenty of air. Like I said, this is a profile that has not caused any issues in the past. Plenty of air remained on both dives, nothing unusual as far as the dives went. I was not cold, and did not over exert myself. I dive solo with a redundant air source in the form of a 13cf pony bottle, which was unused.

Full 3 min. safety stops on both dives.

Had you planned this dive out on tables would you have done it? I

I'd throw that damn computer in a box until until I'd developed the discipline and good sense to plan my dives as square profiles beforehand and then MAYBE allow a little extra for the computers sampling rate.

Yeah I'd call that a deserved hit.

Why use tables at all Jim if you're MAYBE not going to follow them?

Statistically taking a hit from diving within the parameters of modern computers is very, very small already. It would be great to have computer brand and the profiles posted but on first reading, these sound like very ordinary dives except for perhaps the short surface interval.

Good on the OP for not 'shrugging off' the initial symptoms and then following up by calling DAN and going to the hospital. This could have gotten worse.

 

[ianr33]

Sometimes stuff just happens. Deco is not an exact science.

I would consider 3 minutes as a "minimal" safety stop rather than a "full" safety stop though.

 

[mathauck0814]

You are certainly right that using square profiles and tables, you were considerably in violation of NDLs, especially given what you say are the ascent rates. DAN's published study on ascent rates compared 60FPM, 30 FPM, and 10 FPM ascent rates, and the 10 FPM ascent rate was the worst.

Can you link the study? Haven't seen that one.

 

[ianr33]

If that's the study I think it was the methodology was dumb. A 10 ft/minute ascent rate from the bottom is less an ascent rate and more an extension of your bottom time. Need to get up to the depth at which offgassing starts reasonably quickly. A 1 foot/minute slow ascent from a 300 foot dive is not going to help much!

 

[TechDeep]

Good on the OP for not 'shrugging off' the initial symptoms and then following up by calling DAN and going to the hospital. This could have gotten worse.

Had I not lost the use of my arm and hand, I can honestly tell you it would have been shrugged. But what I could not get out of my mind was the way the oxygen resolved the symptoms. Sure, the 2 hour ambulance ride and the 4 hour chamber ride were major inconveniences, but then again, so is waking up paralyzed.

 

[Scubadude_LA]

Although I see some light in all the posts here, food for thought and keeps us in check:

Seems to me that any user error can safely be ruled out here. IMHO the only arguable standout is the somewhat short SI by some standards, but on two dives in this category I too would have relied on the computer monitoring my saturation, flying it without a worry. If not why even wear a computer, they are absolutely useless at that point, just dive it square and if you want to do multi-level then build that into a shorter BT at the deepest depth and spend the residual on the shallower parts of the dive, the extended bottom time from a multi-level computation would be useless if you could not trust it. Granted I wouldn't do that on a trimix dive, it would be table driven with the Predator as a backup. But on these dive, really??

As stated deco is all theory and not exact. We can all have a bad day for no explainable reason. And we all make mistakes.
Sort of interesting to me are the comments on dorking off at say 20' forever at the end of rec dive and such. I do on recreational dives and consider it offgassing, pretty much extending the last stop.

Solid call with the O2 causing the symptoms to subside, classic way to tell for sure. Did you get off the O2 and see if the symptoms came back? Just curious.
Hope you get back in the water soon and get this past you with no residual worries. Any added info you get over time would be appreciated, I'm getting older too

 

[lowviz]

...//...Any ideas on what that could be? I was comfortable with this profile myself until I looked more closely at the tables. If something else is going on, I would sure like to figure out what it is.

Dehydration? DCI Avoidance, decompression sickness / DCS / decompression illness / DCI / diving and the bends, London Recompression & Hyperbaric facilities - The London Diving Chamber

PFO?

Sawtooth dive profile?

Physical stress?

 

[H2O Gal]

Thanks for sharing your story. Just goes to show that you can never predict when DCS can hit--people have pushed the tables and walked away unscathed and others have gotten bent while diving within the limits...