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5 Meters short

A couple of weeks ago, a couple of interns were diving when they came along a chain wrapped around a large concrete block about 18 meters (60 feet) deep. Knowing that if they salvaged the chain, the tank filler Dang could perhaps sell it, Jono whipped out a DSMB. This combination of letters stands for Delayed Surface Marker Buoy. These buoys are carried by divers in a pocket and at the end of the dive they are inflated at about 15 feet/5 meters. The 165cm long, 10cm wide “safety sausage” rises to the surface and serves as a warning for other boats to avoid the area, or it can be used to get the dive boat to pick up the diver. The plan was to tie off the DSMB to the chain, inflate it, and then later they could salvage the chain. These SMB’s have a lot of lift actually, so when they inflated it, it rose up, taking the end of chain with it. However, as the chain was lifted, more and more of it became suspended by the SMB. Interestingly enough, the SMB was capable of lifting about 8 meters of chain. As I mentioned, the SMB’s are deployed from 5 meters, so there is a 5 meter long piece of string attached to the orange tubes. Between the length of chain, and the string, the SMB was still some 5 meters below the surface. No worries, the Jono rose to the surface and took a couple of compass bearings off some landmarks and had the location plotted out. The dive team returned to the boat only to be told that there was no time to recover the chain. The Jono swam back out to get his SMB, but 5 meters is pretty deep. In our silty water he was unable to recover his SMB. Cost off his 5 meter error: $10 for a new SMB. Two weeks had passed and we finally returned to the dive site again. I grabbed Glenn and decided to search for the missing bit of chain. I had the bearings and a depth so I figured we could get very close to the location, then do a search pattern to find it. We swam out to where the bearings crossed then descended. Four meters down we hit coral. Since a circular search is not very practical in areas with large obstructions and the chain was in 18 meters of water Glenn and I headed straight out till we pass the coral. Immediately the bottom dropped to 15 meters. The new problem was that the current was quite strong here. After comparing computers to make sure we both had suitable bottom time I left Glenn in the middle of our circle and swam out about 3 or 4 meters. Glenn had one end of the reel and stayed in the middle of the circle. I would swim around on the other end of the line. When I made a complete circle I would signal to Glenn for more line and make another circle. We had a coral wall on one side so I really only had to make half circles, which made things easier. On the end of the second half circle, I found the SMB, or what was left of it. It was about the size of a postage stamp; the rest of the SMB had been ripped off in the current. Glenn joined me and we untied the string and weight at the end to give that back to Jono. Proof that we’d found his mistake. When Jono had told me about this chain, I had an idea of what we would find, and why Jono’s salvage operation was doomed to fail from the beginning. People generally do not just coil lengths of chain around concrete blocks for divers to locate and swim away with. Never the less, I started to unravel the chain. The current was pretty strong so I removed my fins and handed them to Glenn. Standing on the block I kept running through what was probably 20 meters of chain until I found what I had expected: the chain was securely attached to the block. Jono had found a mooring chain that had sunk after the mooring buoy had either been removed or broken off. Some more inspection on Jono’s part probably would have saved him some trouble and his SMB. Now Glenn and I had some problems of our own though. The current was very strong here and a free ascent would sweep us pretty far away from the boat. Our computers would call for a 3 minute safety stop at 5 meters which would have to be ignored as well. We started pulling ourselves along with our arms and finning to head into the current. I had little hope to find the anchor line in the murky water but figured we could go up current, then head shallower. We’d ignore the safety stop and hopefully end up at the back of the boat with little surface swim. The problem was at 18 meters, air wouldn’t last long. We were working hard but we did find a $10 clip on the bottom. SCORE! Down to the reserve, we suddenly spotted another mooring block. Unlike the one we’d been at just minutes earlier, this one’s chain ran to the surface. When we saw Jono, I told him that we’d found his SMB. “Just a wee bit of patching is required,” we told Jono as he came aboard the boat. I’m not sure he thought the same when he saw the speck of orange at the end of the string.


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