Divers: Myself, a brand new DMC. 26 years old, generally in good shape. Diver 1, about 40, has considerable experience and is a little heavyset, but appears to be in decent shape. Diver 2, also about mid 20's, some experience and in good shape. Both were AOW, myself having complete rescue diver and just started DMC,
Dive Site: USNS Vandenberg. Vis was 30+, current pretty mild for the location.
Being a DMC, I usually get paired with either single divers, or a pair of divers unfamiliar to the area. In this case, in was the later. I was paired up with them, and upon telling them my background, everyone agreed that I should lead the dive. Having probably 15+ dives on the Vandy, I felt pretty good about the dive planning and shared my plan for the first dive. We would descend on ball 5, head to the bridge area, then follow the current back the port side back to the stern. I briefed that despite the plan, we would turn the dive at 1800 psi. Once we descended the mooring line, I did air checks with everyone, and we were all +/- 100 psi with each other. We made out way along the main deck (about 90 fsw) to the bridge, then went up through the structure and out the port side bridge wing. When I checked on everyone's air, we were all at about 1700 PSI, so perfect time to follow the current back to the stern. When we got the mooring line, I did another air check, and the older gentleman was at 700 PSI! At this point I went ahead and offered my octo, as I was at about 1250 psi. He declined, and we began our ascent, with me checking on him every 10 feet or so. At about 30 feet, he ran out of air, and I gave him my octo with 1100 PSI. Once he had the octo, I showed him my SPG to show we were ok on air. The company I work with hangs a tank at 15 feet in case someone does run out of air. Once we safely got to this tank, he switched over, but was getting a lot of seawater with each inhalation. There was another diver close by that saw the situation and was carrying a pony, so he came over and donated the pony reg to the OOA diver, with which we completed the safety stop and made it back to the boat.
Once on the boat, obviously I felt at blame so I talked to the gentleman. He could not have been nicer, didn't blame me at all and was thankful to both myself and the diver with the pony. After a post dive debrief, he wasn't sure why he burned through so much air on the way back to the mooring line. However, he did say that once he saw he was low on air, he started to take quick, shallow breaths, which is something I know now is not conducive to conserving air and actually results in quicker air consumption. Even if there was no hang tank or diver with a pony, we both could have shared air and been safe, as I surface with about 750 PSI remaining. All in all, I think I was more shaken up than he was, me being a new DMC. He had no faults to anyone involved, and our second dive went perfectly and was very enjoyable.
Lessons learned: Be ultra conservative when diving with people you are unfamiliar with. Although we discussed general air plans before the dive, I should have been better with doing checks with those I was guiding. More checks are never a bad thing. Take into account the stress of diving a new location and how that may effect air consumption. I was the only one who had ever dived this fairly large wreck, so they were counting on me to know the proper route. Always take a more conservative approach on the first dive. Had I done this, I would have known more of our limits for the second dive. Lastly, don't be afraid to call a dive. Had I not had a good talk with both my dive group and the divemaster and discussed what had happened and how better to conduct the dive, I probably would have called the second dive on the Vandy, or at least not lead. Luckily I had a lot of support and discussion for lessons learned on the surface interval, so I felt fine guiding the second dive and it went as perfect as could be. I also could have made the approach to the bridge a bit shallower, no reason to transit the entire wreck at 90 feet when I could have done 70 feet, the dropped down to where I wanted to be. a 10 meter difference would have had a significant impact on air consumption given the 450 feet or so we transited. Last lesson learned: if you use a hang tank, remember to turn it off after it is used to prevent any leak during the SI. On my way back down I did secure it, but still, the little details can make the difference. Anyway, I am open to any and all criticism about this dive and want to learn how I can best prevent any of this in the future.
Hopefully this wasn't too long, thanks for any insights! Since then I have guided a ton of dives, all just as planned.
