Accidental DECO and mild panic in a non tech certified diver.

[Soloist]

To the best of my knowledge- there has never, ever been a single documented case of a recreational single tank diver breathing <40% EAN getting an 02 hit at any depth. Not one.

Seriously? We have to go down this road again?

 

[bullfroger]

Want to be the first huh?

 

[scrane]

Perhaps this should also be posted in this thread.
Poor diving techniques I noticed during this week's trip.

 

[caruso]

This wasn't a diving skills issue it was a procedural one.

 

[Johnoly]

....3- I suppose I bear some responsibility ......

NOPE!.....It's not your responsibility to provide a teaching lesson just minutes prior to splashing.

I, like others, see it happen all the time with vacation divers who are following in a straight line of ducks behind the DM along the reef. At the 3/4's point, the DM turns around to everyone and asks them to look at their gauges. Immediately several start heading for the surface because it's the 1st time they looked at it the whole dive. They are just conditioned to follow the DM no matter what.

Thanks for the writeup and glad she's not injured because we all know................panic kills.

 

[Peter69_56]

I have often seen divers with significant number of dives, who do not understand their computer and chose not to research it so they can. It seems they are happy to use it as a depth gauge and little more. On being questioned, they usually respond with "I have no interest in learning any more about it". The premise being that as they dont dive "deep" (and what is deep to them, compared to say me?), they have little need of the NDL timer, or deco information.

Thats sad, as they fail to understand or realise that its packed with essential information about the dive and trying to keep you safe. To have their attiutude is just stupidity at best. They fail to realise due often to their shallow diving, often under shallow piers or offf shallow beaches, that on a boat dive to say 20-30m, you can reach NDL on a single cylinder, thus have a need to understand NDL and deco, even in the most basic form.

Darwinian people at best, but risking the lives of others.

Knowledge is not only power, but safety as well!

 

[Marie13]

Yes, problem there is that due to numerous depth changes, and this wreck in particular has areas of up to 25-30' of relief, that max bottom time based on a fixed depth is going to change.

Even if your depth changes, it still gives you an IDEA of what your NDL will be.

 

[Dan]

We're about a half hour into this deep wreck dive and I've still got about 10 minutes left. I signal to her "is it ok" if I go and check out this forward hold one more time, she glances at her gauges, shrugs an "ok" so in I go, she follows and here I am pointing out 4 huge lionfish when she suddenly bolts for the line and starts ascending like she was about to miss a train.

I catch up to her on the line at 15' and she's totally freaked out- very unlike her. Gesturing, eyes wide, looking all around and pointing to her computer which says DECO, with an up arrow and "10''" and "1 minute". She's stopped at about 15' and has no clue. I calm her down with reassuring signals and gesture she follow me up to 10' but of course that's the last thing she wants to do. Luckily she trusts me when it comes to all things diving and gear related (although possibly not so much after this dive). We get to 10' and the DECO obligation is gone almost immediately.

To my understanding, once you are on DECO, you don't have to go to 10' depth. That's just the depth ceiling for minimum decompression time. At 10' depth, you will accrue the shortest deco obligation time, which is 1 minute in her case. As long as you are ascending at the rate < 33'/min, the deco obligation time will start to decrease. You may even accrue no deco by the time you reach safety stop.

I remember diving passed NDL and seeing my SUUNTO D4 a blinking up arrow with 10 and 4 on left and right side of the blinking up arrow, respectively, indicating that I have passed my NDL and it's time to go up to 10' depth and stay there for 4 minutes. However, as I ascent slowly up to the shallow, the display stopped blinking and the deco obligation time steadily went down to 3, then 2, then 1, then 0, then back to normal NDL display with some remaining bottom time before I reach the 20' depth. At 15' depth, it displayed safety stop with 3 min count down.

So, just take it easy, no rush, especially since she has low air consumption, she should have plenty of air left in her tank.

 

[Caveeagle]

To the best of my knowledge- there has never, ever been a single documented case of a recreational single tank diver breathing <40% EAN getting an 02 hit at any depth. Not one.

FWIW, I calculate my MODs at 1.6, but I dont understand your point that seems to suggest no risk for diving EAN <40% past their MOD.

Whether you are calling dives “recreational” or not. There have most certainly been divers who have o2-toxed diving mixes in the 21-40% range. I would have to dig up specifics, but I do know of a Florida instructor who convulsed doing a deep air dive in Mexico, early 90s.

 

[caruso]

There have most certainly been divers who have o2-toxed diving mixes in the 21-40% range. I would have to dig up specifics, but I do know of a Florida instructor who convulsed doing a deep air dive in Mexico, early 90s.

I'd really like to see one example. Just one. A single tank diver within recreational depths breathing a mixture of 40% or less 02.