Accidental DECO and mild panic in a non tech certified diver.
- Thread starter caruso
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johndiver999
Contributor
If you were going to dive with your sister as a buddy, then you should have set your computer to air OR very carefully monitored her deco status on a 110 ft dive. After 30 minutes, if you had any sense of diving, you would know that she would be in deco or close to it. This is a significant diving error in my book.
In addition, I would not have done what you did with your sister on the ascent. The OP indicates she took off and presumably started to ascend rapidly. In that situation and finding her at 15 feet with a 10 foot ceiling, I would have confirmed adequate gas supply and then I would have her descend to 20 feet or, at least stay at 15. Since she apparently already did an accelerated ascent and had a short deco, I would have cleared it at 15 or 20 and then done a safety stop at 15-20. The deco probably clears a tiny bit faster at 10, but I personally would have encouraged her to stay a little below her deco ceiling if there were no time, gas supply or other issues of significance.
This is really a pretty significant lack of awareness of basic diving protocols. If you are going to do a deeper dive with someone who has the capacity to go way into deco (due to exceptionally low gas usage) and the two divers are using vastly different mixes - you gotta be looking at her computer during the dive.
In addition, I would not have done what you did with your sister on the ascent. The OP indicates she took off and presumably started to ascend rapidly. In that situation and finding her at 15 feet with a 10 foot ceiling, I would have confirmed adequate gas supply and then I would have her descend to 20 feet or, at least stay at 15. Since she apparently already did an accelerated ascent and had a short deco, I would have cleared it at 15 or 20 and then done a safety stop at 15-20. The deco probably clears a tiny bit faster at 10, but I personally would have encouraged her to stay a little below her deco ceiling if there were no time, gas supply or other issues of significance.
This is really a pretty significant lack of awareness of basic diving protocols. If you are going to do a deeper dive with someone who has the capacity to go way into deco (due to exceptionally low gas usage) and the two divers are using vastly different mixes - you gotta be looking at her computer during the dive.
Caveeagle
Contributor
If your point is that risk of exceeding MOD by a few feet when diving EAN36% is virtually zero, ...then I would not try to debate you. However, this is precisely because the entire concept of MOD and risk of o2-tox has been hammered home since Nitrox training has become common. Staying within recreational limits od <130’ and <40% will make it very unlikely you will ever run into an issue. But pushing outer edges of those limits certainly narrows your margin of error.
Think to the pre-90s, where divers would push the limits of air diving, even while in a single tank rec gear profile. I personally know a diver who did several bounce dives to some pretty crazy depths. This was in an era when it was pretty safe to assume nearly all tanks were a consistent 21%. Making light of the potential risk in diving rich EAN mixes is inviting complacency and a disregard for safe boundaries.
Pre-90s is also when we used the 120 Rule. She would have been in deco after ten minutes.
I'll add this addendum to my post on the first page.
I dive a CCR, and have done for a long time now. Most of my buddies are OC.
I wear an OC computer on my right wrist. This allows me to track my buddies deco' obligations. I can switch gases, on it and accelerate the decompression if I wish. By default I set it to air, if my buddy is using Nitrox, i reset the computer before the dive to match.
Having my OC computer gives me an indication of my buddies decompression obligation. At 4 or 5 minutes NST remaining, I will check with my buddy how he/she stands.
An additional note. If you are using a different computer to your buddy, even a different model from the same manufacturer, there is no guarantee that you will have the same NST time, or the same decompression data. (Obviously if either of you has done a dive prior to buddying up then one of you will have a residual nitrogen loading.)
I dive a CCR, and have done for a long time now. Most of my buddies are OC.
I wear an OC computer on my right wrist. This allows me to track my buddies deco' obligations. I can switch gases, on it and accelerate the decompression if I wish. By default I set it to air, if my buddy is using Nitrox, i reset the computer before the dive to match.
Having my OC computer gives me an indication of my buddies decompression obligation. At 4 or 5 minutes NST remaining, I will check with my buddy how he/she stands.
An additional note. If you are using a different computer to your buddy, even a different model from the same manufacturer, there is no guarantee that you will have the same NST time, or the same decompression data. (Obviously if either of you has done a dive prior to buddying up then one of you will have a residual nitrogen loading.)
Thanks for sharing, @caruso. You had to have known what you were opening yourself up for.
I hope that you and your sister will spend some time with one another on the surface, learning/relearning deco theory and her computer.
Online she will find both instructional videos plus a pdf of the manual.
+1 to Dan T's post
Remind your sister that even "mild panic" can kill or injure.
I hope that you and your sister will spend some time with one another on the surface, learning/relearning deco theory and her computer.
Online she will find both instructional videos plus a pdf of the manual.
+1 to Dan T's post
Remind your sister that even "mild panic" can kill or injure.
Yes, 100ft is still 100ft. Doesn't have to be hugely detailed, but it's much easier to gas and plan topside than underwater on the hoof.
Yes.
I remember diving a wreck on the south coast. I was buddied up with a diver i didn't know that well. It was a straight forward 30m ish dive (90-100ft). He was wearing a Suunto like me. We had something like a 30 or 40 minute bottom time planned, so a small amount of deco to do.
He indicated up earlier than I expected, so i popped a DSMB, started the ascent, leveled off at 6m, and started the hang.
After my computer cleared I queried if he was clear to ascend. No, so 3 minutes later I queried again, No. When i checked we had significant time left.
When we finally got out. I found out he had turned the conservative setting on on the computer. The suunto had altitude settings (A0, A1, A2), and Conservative settings (P0,P1, P2). He had turned his up to level P2, the max.
The rest of the boat found it highly amusing that I had spent the shortest time on the bottom and the longest in the water.
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