Type I Bends Hit in Chuuk

[bleeb]

Not to "armchair" this too much but...
I can understand you yielding on the first 21m stop but you really should have spent the rest of it recalculating your obligation to make sure you had it right.

In the interest of understanding the psychology of how bad decisions get made, I'm also curious about this. To put a slightly different slant on things, could the OP maybe comment on what was going on during the 21m/70' to 9m/30' deco stops that could have impacted mentally rechecking the deco profile, such as work load, buddy monitoring, water conditions, etc. The OP commented in post #2 "By this time I now knew we were in trouble, and was praying we did enough time at the deep stops and at the sub-optimal Nitrox 50 segment to ward off a Type 2 Neuro or Spinal DCS Hit." Was this as you reached 6m/20' or was the issue nagging at the back of your mind earlier and only became definite at shallow depths. Not having any deco background, I assume there's a protocol for adding to later stops as soon as you've realized there's a problem with your earlier stops?

Thanks for sharing, and hope you have a full recovery.

 

[nereas]

Nice analysis. Thanks for sharing so we can all learn from it.

Yes, great analysis, thanks!

 

[nereas]

In the interest of understanding the psychology of how bad decisions get made, I'm also curious about this. To put a slightly different slant on things, could the OP maybe comment on what was going on during the 21m/70' to 9m/30' deco stops that could have impacted mentally rechecking the deco profile, such as work load, buddy monitoring, water conditions, etc. The OP commented in post #2 "By this time I now knew we were in trouble, and was praying we did enough time at the deep stops and at the sub-optimal Nitrox 50 segment to ward off a Type 2 Neuro or Spinal DCS Hit." Was this as you reached 6m/20' or was the issue nagging at the back of your mind earlier and only became definite at shallow depths. Not having any deco background, I assume there's a protocol for adding to later stops as soon as you've realized there's a problem with your earlier stops?

Thanks for sharing, and hope you have a full recovery.

Peer pressure, even only a peer of 1, is often the cause of many bad decisions.

Take a look at the subprime mortgage market!

 

[mselenaous]

Kev,
Thanks for sharing the learning experience with everyone. Glad to see you back in the water again a few weeks ago on the Mr C.
Happy Holidays,

 

[Kevrumbo]

In the interest of understanding the psychology of how bad decisions get made, I'm also curious about this. To put a slightly different slant on things, could the OP maybe comment on what was going on during the 21m/70' to 9m/30' deco stops that could have impacted mentally rechecking the deco profile, such as work load, buddy monitoring, water conditions, etc. The OP commented in post #2 "By this time I now knew we were in trouble, and was praying we did enough time at the deep stops and at the sub-optimal Nitrox 50 segment to ward off a Type 2 Neuro or Spinal DCS Hit." Was this as you reached 6m/20' or was the issue nagging at the back of your mind earlier and only became definite at shallow depths. Not having any deco background, I assume there's a protocol for adding to later stops as soon as you've realized there's a problem with your earlier stops?

Thanks for sharing, and hope you have a full recovery.

What was overwhelming was trying to reconcile quantitatively my buddy's running deco profile with the profile I recalculated on-the-fly after extending the bottom time. Intuitively, his deco stops through the Eanx 50 range (21m/70' to 9m/30') as we progressed felt "short" --and then my brain processing capacity became utterly saturated. I assumed we were going to make it up by adding time to later stops through the Oxygen range (6m/20' to-the-surface) [yes, to answer your question there is a protocol].

My dive buddy had contingency tables in his wetnotes, based on the program called Decoplanner; these tables were slightly more liberal than the profiles I was used to using --so I decided to continue with my buddy leading the decompression profile and ascent. It was when we completed the Eanx 50 range that I realized that nearly 30% reduction in the expected time for the 21m/70' to 9m/30' range was drastically less than the norm . . .it was then I knew we made a serious error in reformulating the deco ascent profile.

 

[Rick Murchison]

... It was when we completed the Eanx 50 range that I realized that nearly 30% reduction in the expected time for the 21m/70' to 9m/30' range was drastically less than the norm . . .it was then I knew we made a serious error in reformulating the deco ascent profile.

Even then y'all would probably have been ok if you'd extended your time at 20' to the end of your oxygen and (weather permitting) 10' for an hour or so (or as long as you could).
Here's the Navy Air table for the dive:
40 - 2
30 - 16
20 - 23
10 - 55
And that's without the benefit of any accelerated deco.
As I said earlier, extending those shallow stops can "forgive" lots of mistakes deep.
Rick

 

[robint]

although I am not a tech diver, I do really appreciate this post and discussions. This is another reason I will never go tech, it is too much figuring/calculating and I hate that. It just isn't for me. My only comments about the dive are #1 - making a decision to change the dive plan at 150' depth isn't good , and #2 - Rick, I like your rules, especially the second one about keeping plans simple. Any time my buddy and I have had issues underwater, it has been because one of us changed the dive plan during the dive and the other person didn't understand all the signals, causing confusion for both of us. It has never caused us to go to a chamber, or even close, but we have had some heated arguments back on the boat!

Kevrumbo, glad all is okay with you and that you learned a valuable lesson!

robin

 

[Ayisha]

...In retrospect, that was a very bad decision as well to delay Hyperbaric Oxygen Therapy (HBOT) as noted above (the Hyperbaric Doc's in Hawaii, and my Supervisor Karl Huggins at the Catalina Hyperbaric Chamber really reprimanded me hard for that one!). Even with resolution of symptoms just by breathing O2 at 1atm for a day, it still would have been risky & foolish to continue diving after such an injury, with potential pathological bubbles still residing in my circulatory system. . .

Hey Kev,

When I did a tour of the Catalina chamber last year, Karl also told us (in laymen's terms) that one of the reasons that treatment should begin as quickly as possible is that when the nitrogen bubbles expand, they can move organs/tissues etc. out of the way of the bubble and cause damage. When the bubble reduces, the hole left by the bubble and the resulting negative consequences can remain. Karl said that if treatment is begun immediately, the chances of permanent damage is reduced, while the more treatment is delayed, the more the chances of residual damage from the effects of the bubbles.

Karl said it more eloquently, and we all got the point!

 

[dumpsterDiver]

I do lotsa dives on air deeper than that solo. I would never consider changing the dive plan and extending the planned bottom time by that much. Maybe I will cheat a few minutes to chase a fish, but not something like add on another 20 minutes BT, on top of a know deco dive. If I even felt the temptation to do something like that, I think I would abort the dive because I would recognize it as a stupid impulse that would be indicative of significant impairment.

Maybe the narcosis was enough at depth to make you stupid, but why would you compound your errors by blowing off deeper stops too? I would not delegate thinking to another diver unless I was totally scared or completely over my head in an emergency, and none of these situations seem to apply.

I have a pretty good idea of my planned deco before a dive and then pretty much follow my computer to get me to the surface, plus I add some deep stops and oxygen (that the computer doesn't know about). If you had simply followed a computer on ascent, it sounds like you would have been fine.

If you are going to act like an idiot underwater, at least look at the computer!!!

 

[Charlie99]

By this time I now knew we were in trouble, and was praying we did enough time at the deep stops and at the sub-optimal Nitrox 50 segment to ward off a Type 2 Neuro or Spinal DCS Hit.

At the 6m/20 O2 switch, I was going to signal my Buddy to do a 30 minute Oxygen Segment, with the sequence 10:5:10:5 (i.e. 10min on O2:5min Backgas Break etc.) with an nice slow 1m/min or 3'/min ascent to surface on Oxygen. He immediately signs back at me a 12:6 sequence, so I think to myself, "Great . . .I'll just signal an additional 12 minute period on O2 after the 6 minute Backgas Break.

Did your buddy ever realize that you had major concerns about the deco by the time you started the several minute long 30' and 20' stops?

Did you have wetnotes or a slate to communicate?