I thought I might provide the other half of Mike G's diving experience off the Sanctuary at Aumentos Reef last Saturday and fill in some of the missing information. I'm Greg, Mike G's buddy for that dive. There's plenty to be learned by all involved. Here we go:
Background on tech divers that MIke G hooked up with:
Both were experienced IANTD divers and said they'd been down to 300 fsw. Both were breathing Nitrox as their main gas. Tech diver 1 had an LP85 stage bottle (yes an 85) of unknown content, tech diver 2 had 40cuft stage bottle with 50% O2. During their first dive at Fire Rock, both tech divers incurred a 5 min deco obligation. I didn't inquire about the profile of their second dive at Aumentos. Marker gear: one of the tech divers and a 185# Halcyon lift bag and a 6" LP hose on his stage bottle to inflate it with. He'd removed the LP hose locking feature to simplify inflating the bag. He also said that his method of deploying the bag was to connect his reel to it, inflate as appropriate, then drop the reel, then release the bag while letting the cave line run between his thumb and index finger. He said the bag shots to the surface faster than the reel lets line out and that the reel rises to his hand. It must take a bit of practice to pull that off.
Aumentos Dive Summary:
During the dive briefing, the captain warned us that we were in a high traffic area and to be sure to ascend on the anchor line or deploy a surface marker at depth prior to surfacing. On board Mike G and I buddied up. Mike M buddied up with the "other diver" whose name none of us recall. Mike M and "other diver" (Team A) planned to descend and remain near the anchor. The four of us then agreed to dive as a team of two buddy pairs. I made it clear to everyone that if Mike G and I decided to leave Team A that we'd let them know before we left. Then all four of us met at the anchor line. The current was so strong that only Team A could hold on to the anchor line, so I held on to "other divers" tank valve while we waited for Mike G to join us.
When Mike G arrived, I reviewed the plan again including that Mike G and I would let Team A know if we decided to leave. Everyone acknowledged the plan and Team A descended. Mike G and I agreed to descend, I descended first. At 30 ft I stopped to look up and check on Mike G. He was at ~10ft. I signaled OK, he replied with OK. I resumed my descent and joined Team A. I looked up the anchor line and could see the faint silhouette of the boat, but Mike G was not there.
Analysis: I assumed Mike G had aborted the dive and re-boarded the boat because he'd been ill the entire trip. I felt sure that I could have seen him if he had been in the water. In fact, I should have surfaced to look for him. As it turned out, however, I wouldn't have found Mike G because he decided to continue his descent after he was swept away from the anchor line, and he eventually hooked up with the tech divers.
Analysis: When Mike G let go of the anchor line to clear his mask and was swept away by the current, he should have assumed the current would remain just as strong at depth, which it was, and surfaced.
So, the dive continues with me buddied up with Team A. At approximately 25 minutes (guessing) into the dive, Mike M decided he was low on air and needed to surface. Neither the "other diver" nor I were aware that Mike M had decided to leave.
Analysis: Mike M didn't let me or his other buddy know that he was leaving. Had I known that Mike M needed to ascend, we would have called the dive. Mike M put himself at unnecessary risk and should have insisted that we end the dive.
Analysis: When "other diver" and I realized Mike M was missing, we should have searched for him and then surfaced instead of continuing the dive.
35 minutes into the dive the "other diver" wanted to surface due to low air. We agreed to end the dive. I swam toward the anchor and found it dragging across the sand floor and then lift and rise to the surface. This must be at the 5 minute point of the 10 minutes that Mike G was on the surface waiting for the Sanctuary to pick him up after leaving the tech divers.
"Other diver" and I began our ascent. I held my safety stop for 4 min given that both dives were relatively deep and because I chose to hold it at 20ft to avoid being struck by a passing boat. I also pulled out my non-dump valve equipped surface marker. I attempted to inflate it, but as Mike G explained, my lips seemed to be too cold to inflate it at 20 ft depth. My plan was to hold it above me so that it would surface somewhat before I did - better than nothing.
By the time I surfaced, the Sanctuary was back waiting to pick me and "other diver" up with Mike G onboard. The crew hustled us onboard then drove over the pick up the tech divers. They had orally inflated an SMB at depth and reeled it to the surface.
So, I hope the individuals involved don't feel that I'm laying any blame on them, because I'm not. What I do want is an accurate record of the incident and enough information for everyone to learn from it.
Conclusions:
- Diving in a group tends to weaken buddy bonds. That's what happened here and I've seen it happen with other large diver teams. Try to resist it.
- Surface deployable SMB are difficult to use at depth in cold water and offer limited boat strike protection if you can't surface it at depth.
- We should have asked the Sanctuary to deploy its current line before we started the dive.