Did everything right ( I think) still, buddy got bent??

[nitrojunki]

Narcosis, any chance in sharing the name of the instructor? I would like a chance to avoid instructors that do not pay closer attention to the students.

 

[Hank49]

Dave,

You didn't mention if you were diving tables or computers and which ones.

If you were diving tables, 108 ft for 35 minutes puts you on a staged decompression dive with a 2 minute stop at 20 feet followed by a 21 minute stop at 10 feet. I don't know if you made the required stops, but you followed it up with a 35 ft dive for 40 minutes. As an L diver (assuming you made the 2 decompression stops), your max bottom time at 35 feet was 39 minutes. You should have made a 2 minute stop at 10 feet.

"Saturday at 3:00 pm we did a dive to 108 feet averaging 65 feet for 35 minutes, a SI of 18 minutes and then a 2nd dive to 35 feet averaging 22 feet for 40 minutes".

Walter, if he stayed at 108 feet for 35 minutes he would have needed all that deco but he says, and I don't know how he figures this, that he averaged only 65 feet. Same for the second dive...an average of only 22 feet, so he should have been credited some off gassing time and shouldn't have needed the whole 23 minutes deco on the first dive. Or am I missing something?

 

[Teamcasa]

I’m going to print this post out, including the bounce dive info and go over it with my newly certified brother who wants to set some personal deep dive record right away.

I am glad everyone is OK now.

 

[Walter]

"Saturday at 3:00 pm we did a dive to 108 feet averaging 65 feet for 35 minutes, a SI of 18 minutes and then a 2nd dive to 35 feet averaging 22 feet for 40 minutes".

Walter, if he stayed at 108 feet for 35 minutes he would have needed all that deco but he says, and I don't know how he figures this, that he averaged only 65 feet. Same for the second dive...an average of only 22 feet, so he should have been credited some off gassing time and shouldn't have needed the whole 23 minutes deco on the first dive. Or am I missing something?

You're missing where I said, "If you were diving tables." If they were diving computers, they certainly would get credit for shallower portions of the dives. Computers are a great deal less conservative than tables for exactly that reason. I dive computers to get more bottom time, but you need to be aware when you are pushing limits. Dives with profiles like this are pushing limits. I might make a no staged decompression dive with my computer that would result in minimal decompression on tables, but tables would have required over two hours of staged decompression. Over two hours is not minimal decompression. I never use "average depth" in calculating decompression status and I do not believe it is a wise practice.

BTW, 131 feet for 62 minutes requires a 4 minute stop at 40 ft, a 19 minute stop at 30 feet a 32 minute stop at 20 feet and a 68 minute stop at 10 feet.

The online table I was reading earlier today was not very clear and it resulted in me misreading the table. If it had been a 130 ft dive, it would have required a 16 minute stop (not 6) at 30 ft. The rest of the stops are as earlier reported.

 

[sea nmf]

Hi

In the end I'm left to wonder why. We did everything by the book (except for the short SI's) we did deco stops using 50% EANx even though our computers said we didn't need to. The instructor and myself didn't bend? I just don't get it.



Dave.

Even if there were no problem with the profiles, by you admitting that the SIs were too short, you have to know that it wasn't by the book. That alone could account for the DCI.

 

[DiverBizz]

I just cant believe you had such short SI between all dives. How could this be a class with a certified instructor?

 

[dumpsterDiver]

The information is too vague for me to decide just how agressive those dives were. If you maxed out the computer on the bottom and then ascended so slowly that you continued to max out at shallower depths, then the deep dive could have been very agressive. I am amazed that an instructor would select profiles (and particularly, the short SI) that you described for a training activity. Certainly not good practice.

Lots of people can get away with diving agressive profiles similar to what you might have done (but with longer SI). But I believe that you really need to be careful when you first start doing aggresive profiles.

Progressing slowly into stupidity is sometimes safer than jumping. I know commercial fisherman that do agressive profiles every day, but I think that this type of diving can not be handled by most people and probably shouldn't be done by anyone.

The only scary part about the whole story is that you seem to be so surprised by the outcome.

 

[z3r0c00l]

I get the feeling he also used the 50-50 gas to reduce decompression - a more conservative choice is to pretend 50-50 is air for decompression times, while also keeping in mind your O2 levels and clock. Decompression is harder for a reason - it is a difficult process that is not an exact science. Your first decomp dive could have been simply a longer dive at 100 feet btw...

 

[PerroneFord]

The only scary part about the whole story is that you seem to be so surprised by the outcome.

Let's see...

Multi-day deco diving..... check
Dives below 100ft.... check
Surface intervals too short to allow bubbling to stop.... check
Bounce dives.... check
Ignoring signs of bends and continuing to dive...check
No oxygen cleanup (yes I know IANTD gives you 50% first)... check


So, all the makings of a potential monster case of DCI, and yet the divers and apparently the instructor can't seem to figure out what went wrong.


In your position here's what I would do:

1. Demand money back from instructor based on incompetence.
2. Contact IANTD with this story. Send a message to Dituri or Mount personally.
3. Stop decompression diving until you understand the issues more clearly
4. Locate a real instructor who does this kind of diving regularly and understands it.
5. Do not do another deco dive without available oxygen
6. Get a PFO test if you plan to do decompression diving.


I am glad you are both ok, but quite frankly, I'm more surprised you're not in a hospital than you are that something went wrong. Actually, you can probably skip the PFO test. You all just gave yourself a few of them underwater. Good news is you all passed.

(No I am not a doctor, and you probably should get the PFO test done anyway.)

 

[DiveBandit]

Hey folks, thanks for the info thus far.

To answer some of your questions. The dives were planned on IANTD tables (it was an IANTD class), and we were using a 50% 02 deco mix. We just happened to also be wearing our Sunnto computers which didn't show any deco time by the time we got to 20 feet, thats why I said we did the stops even though the computer said we didn't neet to. We did a 3 minute stop at 20 feet and a 13 minute stop at 15 feet as per the tables. I figured the SI's were kinda short, but i figured the instructor knew what he was doing.