Quote: (Originally Posted by
jkaterenchuk)
G
I wonder what others have done in this same situation?
John
I applaud the diver for halting this chain of events in time
.
something Dave Sutton wrote a while back really stuck in my mind. He mentioned that people are too afraid of O2 and are too reluctant to use it. He mentioned being quite liberal with it on ascent and in the shallows, something I have taken to heart as it seems that the biggest common denominator is hypoxia.
since picking up manual CCR diving, the school of livable consequences has taught me to lay on the manual 02 add on a regular basis as a matter of course in the shallows.
In this case i would have laid on the o2 and then cross checked my po2 on my HUD with the po2 on my handset, but I can see logic in having the dilluent be the default as it's more likely to give you a breathable gas at the surface and at depth. If you are going to leave one thing to reflex I can see why we are taught to go with a dilluent flush.
The one thing I concluded from the "oh so wonderful" discussion on HUD design is that mCCR's in particular really need real time po2 on the HUD and that the color of the lights are not so critical because you are always interpreting the real number rather than expecting an alarm to allert you that something is wrong (or in this case, getting in the habit of ignoring it). Set point has become an optimal range rather than a single point for me. I keep it up about as high as I can at or near the surface with regular, liberal pushes on the manual o2 add button (.6-.9) and then bump it up as it becomes easier as I go deeper (1.1-1..4).
And to be clear, I don't think mCCR's are "safer", it's more that they engender a school of livable consequences where it appears that pretty consistently such events are near misses rather than fatalities. I think it's because the diver is forced into a pattern of habitual po2 monitoring, being much more likely to react in time even when distracted (in this case, the last possible second still counts). With each screw up or near miss the diver is compelled to ramp up the monitoring interval, entraining a monitoring interval that actually relates to necessity.
When I owned and dove the evolution, I never really knew when I was monitoring enough... the question on my mind was always, when's the system going to fail, not when am I going to fail the system. When I felt relaxed, I'd do it less, when I felt a little nervous, I'd do it more and nothing could be more erroneous. Conversely the more relaxed I became, the more prone to error I was.