Had a similar experience with a school classmate who came over to El Salvador to dive while I was just starting my DM training. Knowing he was a little hard headed, I decided to give him the benefit of the doubt (it had been over two years since we had graduated, he had got his OW license, maybe he opened his mind a bit). As soon as we got on the boat, I started to see my friend just I remembered him when he had a little trouble setting up his gear.
I quote my friend: "Where I learned the inflator hose was over the right shoulder".
Riiiiiiiight. I just smiled and reassured him that on every BCD I have seen it is over the left shoulder. But, anyway, I helped him do his predive safety check and we were in the water.
Immediately the group went left and my friend went right. I started banging on my tank to get the attention of the instructor who - with a certain twinkle in his eye - pointed at me, pointed at my friend, and made the buddy sign. I understood. I was to catch him.
I spent the rest of the dive keeping equidistant from the instructor and my friend to the limit of the visibility (maybe 5-10m). When I had to make a choice between the two I would swim over to my friend, get his attention, and signal back over towards the direction of the group. Apart from a slight issue with him shooting up towards the surface at random intervals, we finished the dive "without too many problems".
On the second dive we went to a wreck where all that remained was the skeleton of the hull. The visibility was less than 5m and the surge was increasing. Needless to say, group went left, friend went right. I got the instructor's attention and signaled I was going to catch him. Once I caught up to my friend, I realized my wife thought I was signalling to her to follow and before I knew it we were all three separated from the group.
Luckily, I knew the layout of the ship well and we had said if we got seperated we would meet at the tower of the ship. So I grabbed my friend and signalled to my wife the direction of the tower. We all made it back to the tower and were reunited with the group. Phew!
A great lesson for me that day. I felt like I did everything right and the instructor thanked me for the support with a wink and a smile. It was definately a challenge, most of all because as much as I wanted the group group to stay together and swim like little ducks in a line, I knew the my friend was in need and I was sure that the other divers had the necessary skills.
It's a lot of tough decisions, but I have to say this far I have loved every dive.
A