Tuesday, August 7, 2012

Commercial Diving - Divers: Nakai; Esteban & Sergio

Our dive focus changed during the last two week ends. We received a call from a Marine Shipping Agency to locate and move a 3000 lbs anchor and chain gear from a 30 feet deep location to the original 60 feet sand patch. This kind of anchoring systems  are used by the barges and some freighters while at G.T. Harbor.
We set out very early on a Saturday loaded with our commercial equipment and rigging including lift bags, chains, shackles, ropes, etc.
We were told the chain had a marker up on the surface. To our surprise we found the marker way off shore by the actual drop off. Once moored in place, we dove down to investigate. Our findings were the giant mooring buoy was still attached to the chain being held by the weight of the anchor at about 45 feet of water. The anchor was teetering at the very edge of the wall in 140 feet of water and we estimated its weight at over 4000 lbs may be 6000 lbs. In a very precarious position ready to fall into the blue!
We realized the maneuver had to change now from "moving" to "securing" the rigging so as to not loose it.
We worked hard inspecting the deep area, setting up lift bags and finally connecting a tow line from the Bloody Bay tug boat to the chain. With all these forces in place we managed to move the kit up the wall to a more stable area away fro the drop off and about 20 feet shallower. Unfortunately the tug boat Captain was not very delicate and the tow line broke. Having ran out of bottom time and late into the day, we had to stop operations until next week end.
Following Friday and after showing our findings to the shipping agency, we were provided with an extra 6000 lbs lift bag and we set out to complete the job as stage 2.
Two other divers came with us. The Tug Boat took the mooring line attached to the buoy and we rafted next to them. The 6000 lbs bag was taken down and inflated but the anchor stay down. Then we added our own bags and with a total up force of close to 9000 lbs of lift, the anchor was "light" but did not abandoned the sea floor.


Our next and last resort was to connect a deep tow line by the anchor. Esteban and I descended to set the sling and giant tow rope and shackle close to the anchor shank. After our safety stops we descended once more now to 90 feet and 70 feet to re-inflate the bags for maximum lifting power. Back on the surface, we prepared the Tug for the towing operation with the snag that the big floating line and one big shackle drifted under the props of the Tug, so we had to stop and dive for a few minutes to clear the line.
As soon as a light pull was exerted by the Tug, the giant metal buoy and two of the lift bags came to the surface, clearing the anchor from the bottom floor and allowing the Tug to re- position the anchor. The other two divers guided from the surface the direction for the Tug to go and do the drop. A great flat sandy area was found in about 60 feet away from coral heads and the drop off. Anchor was set down, all bags and gear cleared out and the operation was completed before the approaching storm (that is here now!).
Last Sunday though Esteban and I returned to the area and retrieved a  mooring line and thimble for big freighters (weighing about 100 lbs). We found the piece while inspecting the area however we had ran out of bottom time at those depth to effect the salvage at the time.
Until next dive!

No comments:

Post a Comment