The following happened yesterday off the coast of Miami. I've been following this thread and find it appropriate. I'm being serious right now, and I don't feel like getting bashed, so be careful on how you respond. I plan my dives based on my air consumption and task to be completed. I use the rule of thirds. I normally dive solo, whether in a group or not.
We've been diving a few wrecks off Miami for the last few days while the weather was good. Yesterday, the weather (for SE FL divers) wasn't all that appetising, so only two of us showed to the boat for a noon departure. The other guy used to be an instructor down here, although he seemed a little rusty on the previous days less demanding dive. Since there was only two of us going diving, the divemaster(good friend of mine) asked me if I would pair up with this other guy since he(the other guy) hadn't been on this wreck in many years. Against my own judgement, I said yes.
Now, my plan was to get on the wreck via the down line tied off on the bow, enter cargo bays 1 and 2, and then return to the line. I briefed my 'buddy', who was diving air (I was on Nitrox ean29) that I would under no circumstances be entering any overhead environments on this dive. He agreed. My bottom time would be about 10 minutes longer than his, and I planned a NDL dive. My cylinder reflected my dive time with 1/3 for reserve.
I entered the water and descended. When I reached the wreck, he was 8 minutes behind me. We explored CB1 and entered CB2. Upon descending into CB2, I checked him to see if he was OK. He gave the forefinger to thumb OK. I found a lure tangled in some line up under the overhang, so I pulled out my knife to retrieve it. When I turned around, he was gone and the bay(about 30 ft deep) was completely silted out. I couldn't see anything, but knew there was a passage leading into the ship. My dive computer started beeping with 5 minutes to Deco. Normally, this would be my turnaround time, and I would head back to the line. I banged on my tank to see if he would respond. He didn't. I started up to see if he was on top of the wreck. He wasn't. I looked towards the stern, and then started towards the bow to the line. I passed over the 1st bay and no sign of bubbles. When I reached the line, I was entering Deco.
The divemaster was on his way down, as he had timed his reentry based on my profile. He was at about 100' when I picked up his shadow. I signaled him with my light and he raced down the line. I signed to him that the other guy was missing. I looked at my computer and decided I could spend less than 2 minutes getting him searching in the right direction. We fought the current aft on the ship and upon reaching the 2nd bay, we saw bubbles. I signaled low on air and returned to the line. I had the current on my side and ascended diagnally toward the line reaching it at 100'.
I made a stop at 30' and didn't see them coming up behind me. I made a stop at 15' and saw their bubbles coming up the line. As we drifted on the upline at 15', I came out of deco, but had a severe CO2 headache from overexertion in the process of the search. On the line at 100' up to 30', I was concerned about a CO2 blackout as I was still overbreathing my regulator. Without any other diver around, and not being able to surface, I was more than nervous. By the time I got in the boat, my gas was at 125psi.
Now, don't all jump on the bandwagon and say I had poor gas planning. I planned one third for descent and exploration to the turnaround. I dived it. I planned one third for turnaround to the line and ascent. I used all of this and more during the search, the return to the line, and the short seach with the divemaster. Based on my modified plan during the event, my reserve got me through my short hangs and into the boat.
Here's the problem. My back gas gave me a standard reserve that I used. However, it did not give me adequate reserve to conduct an adequate search. Had I not extended myself, this other guy would be a victim of his narcosis and entry into the wreck. I'm trained and I'm meticulous about equip and proceedure. This guy was not, but it wasn't part of the dive plan. Had I been carrying a pony (not planned as part of my operational gas), I could have used it to deco on the line, which would have allowed me to go further into deco on the search.
What is planned, and the reality of a dive gone wrong can be too far apart to not carry a pony. Some will say I should have been diving doubles. I planned a dive that didn't need doubles. I planned a dive that didn't need a pony. Only after a diver getting narced and off plan, did that contention come into play. That could have happened in 60' and a thorough search could have required doubles. Not going to happen. A pony is not a crutch to knowledgeable divers - it is a tool. A tool just as important as an H-valve, sheers, and reel.
