... I'd like to hear more of the specifics of your dive...
In my case, the prudent gas plan called for two bottom gas tanks rather than the single 80's we ended up using. In those days Nitrox had just become available on the Island - still no ready source of Helium - and we used a 32% travel gas staged at 130', with a line run from the stages to the wreck. To make a long story short...
(1) my safe second started a "small" freeflow at 180' or so. No big deal, I just switched to that one and breathed it... the increase in gas consumption was tolerable and I'd watch it closely.
(2) my #1 buddy (over 5000 dives) wanted to stretch our planned bottom time by "just a little." Ok... but only a very little - one minute.
(3) when we came up to the top of the hull for our swim back to the line, a little current on the nose had picked up - had to work a little to get back to the line.
(4) I decided I had enough gas to retrieve the line rather than make the direct swim to our stage bottles (my buddies did take the direct route).
---
Analysis:
A 200' dive on air becomes a serious overhead environment after only a few minutes. Any catastrophic gas failure requiring an ascent all the way to the surface would be certain DCS, perhaps even fatal (see "Rouse.") I made two stupid decisions on this one. First, the decision to go with a single bottle of bottom gas was stupid. Had my freeflow been a serious one I'd have been totally dependent on my buddies to get me back to my stage bottle, and with the current picking up they weren't much better off on gas supply than I was. Second, the decision to leave the nitrox stages at MOD was stupid. The reasoning was, of course, to eliminate the possibility of getting confused and breathing the wrong gas at depth - a reasoning that made sense when carrying two bottom gas bottles and enough bottom gas to execute an air deco profile in the event we got blown off the wreck and couldn't get back to the stages, but double stupid considering we'd decided to carry only one bottom gas bottle. That nitrox would be just fine for an emergency ascent to first stop depth, and I should have kept it with me.
Next three stupid decisions were the handling of the three minor glitches to the plan that occured.
The mild freeflow - I knew immediately why it was happening. I'd rigged a Conshelf second on a Legend first. The Legend is overbalanced and increases IP over ambient as you go deep. My Conshelf was tuned for a lower, constant IP. So I was confident it wouldn't go ballistic on me, but also confident I couldn't stop it with a standard pop-on-the-palm. The decision to breathe that second stage was ok; the decision to continue the dive was stupid, and probably influenced by a narcotic "inappropriate feeling of well being" from air at 180'. The decision on how to handle a freeflow - even a small one - on a deep air dive should be made on the surface, not at 180'. Abort opportunity passed up. Stupid.
Next, my most experienced buddy wanted to stretch bottom time just a little. I should have thumbed it. How many times have I preached "dive the plan" over the years? Again, I can claim narcosis as a contributing factor, but that's no excuse at all. Part of the plan is to *not* get bright ideas on deep air, and to stick rigidly to the planned profile (or make it shorter/shallower). I had enough gas, but... another opportunity to be less than stupid passed up.
When we reached the top of the hull and noticed we had a little current to swim against to get back to the guideline, I made the (stupid) decision to go get the line and follow it, even though the visibility was at least 100' and it was easy to cut the corner to the reef and the stage bottles. (the geometry was a near equilateral triangle, so going for the line was twice as far as the stage bottles, and that first leg was directly into the current at 165', where cutting the corner would have allowed an immediate ascent to 130' and a track at 60 degrees off-current - and I must add that the spool in question was one of my el-cheapo homemade jobs that couldn't have cost more than $5, including the line and brass snap) I wasn't going the leave any evidence of my stupidity behind though, so using my Naval Aviator logic of "better to die than look bad" I made the long up-current swim to where the spool was tied off and dutifully wound it up to the stage, arriving with 156 psi on the digital readout. Stupid.
Made it, though, and it was a long time ago and nobody has pictures so you can't prove it
Rick
