bywarren said: There can be many warning signs that a dive should be aborted, both before and during the dive.
seashell replies: This is true and should be heeded. By the same token, it's not like it is really common either.
bywarren said: I personally know a former dive master who has permanent neurological damage from having to chase a diver who got nacrosis and went the "wrong way". Any diver who allows themselves to experience narcosis is putting both themselves and others in danger.
seashell replies: Do you dive by? Everyone experiences narcosis to some degree whether they admit/accept that or not. In any event, your DM buddy did not get neurological damage from going deeper. Perhaps going deeper caused him to accumulate deco time that he blew off, or perhaps he ascended to rapidly for some other reason, but it wasn't the going deeper that caused his neurological symptoms. If he was chasing a diver who was ascending too rapidly, in an effort to stop that diver's too rapid ascent, that could cause the problems to which you refer. In that event, narcosis would have abated as the divers went more shallow. If narcosis was indeed involved in this circumstance, perhaps your DM buddy meant that the diver in question, became agitated at depth due to narcosis and panicked and went rapidly for the surface?
bywarren said: The Blue Hole dive is not a dive where the dive masters should have to watch 20 divers at 20 different depths trying to avoid narcosis.
seashell replies: Agreed, however, that is not what I said either. If a diver feels significantly narced they can often alleviate the symptoms by ascending a foot or so. Ergo, if the diver is at 133' and feels a bit giddy, then ascending to 130' may be all that is needed to feel more normal.
This is another reason that I always recommend that the divers intending to do the Blue Hole, do some deep dives before they go to BH. That way they will have some idea of how they may feel. There is no guarantee of degree of narcosis at a certain depth. Some people are more affected by it than others, and some people are more affected by it different days and at different depths. Who knows maybe it has to do with lack of sleep, hydration, mood, rate of descent or the phases of the moon (joke). Ergo, you just need to learn to recognize it within yourself early enough so that you can take steps to ascend a foot or so, if need be.
bywarren said: It is just my opinion that if a diver gets narcosis on a group dive when the profile is to dive to depths of 130ft or greater, they should abort their dive for both their own safety and the safety of the others.
seashell replies: Well, that's a difficult call. Once you are at 130' on the Blue Hole dive, (or even higher) abrupt abort can actually create a safety hazard for the aborting diver, their buddy and others in the water. Better to learn to recognize your symptoms and ascend a foot or so until you feel less giddy. Pause, think, react. After you have ascended that foot or so, and are feeling less giddy, you can try to descend again, often the narcosis will not be as noticeable on the second attempt to go to depth.
bywarren said: There is no reason to hang out at 80ft in the Blue Hole where there is nothing to see and have the dive master not be able to devote all of his attention to the divers that are diving the planed dive.
seashell replies: Certainly not, and I've never advocated anything of the sort. bywarren have you ever made the Blue Hole dive?
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