More than 500 t of debris has been -removed from the field surrounding the wreck but the weather is challenging…
Nautical failure was the reason why container ship »Rena« ran aground off New Zealand, close to the port of Tauranga[ds_preview], in October 2011. More than one and a half years later wreck removal and recovery of cargo is still going on. Svitzer reached the vessel five days after grounding and started to pump out the remaining fuel oil. Braemer Howells and Unimar were in charge of recovering wreckage and cargo as well as of cleaning up the coast and coastal waters. In July 2012 Resolve was initially retained by Swedish Club to reduce the bow section to 1 m below the lowest astronomical tide. After the vessel broke up on the reef in early 2012, the bow section remained atop the highest point of the Astrolabe Reef while the stern settled at a depth up to 65 m below. Surrounding the two sections was a debris field of approximately 10,000 m2 comprising mostly metal wreckage from the ship and cargo containers. To date, more than 500 t of debris has been removed from the field. Debris recovery for the coastline of the Bay of Plenty mainland and islands is continuing.
The salvage plan for the bow provides the use of helicopters to lift cut sections weighing as much as 3 t to a nearby barge. The bow section continued to list during the operation, and reached 34° to starboard. As the bow reduction came close to completion, Resolve began the debris field cleanup operation. The »RMG280« shear leg crane barge was used to raise wreckage weighing up to 50 t from the reef and from deeper water. Resolve has applied multiple, sophisticated technologies including Ultra Short Base Line or USBL Accoustic synchronized with on-site navigational technology. Diver tracking, Bathymetric Data and GPS positioning of the barge and crane are integrated to provide real time imaging of the entire operation.
The 11,000 t stern section is fully submerged and resting at a 55–60° list on the reef. The deepest part is lying in 65 m of water, with the top of the accommodation block 10 m beneath the surface. The exterior of the accommodation block is substantially intact. The hold covers have broken away from the hull and much of the cargo has spilled into the debris field. Inside the hull the tangle of debris makes it difficult to determine what cargo remains in the lower holds.
Heavy weather conditions have been the greatest challenge for the salvage team. Astrolabe Reef is in an exposed location and is subjected to open-sea conditions with swells of up to 8 m. The reef rises steeply from the sea floor, which amplifies swell and wave energy at the surface. When seas are too high to allow for wreck cutting operations at the reef, the barge can pull back to deeper water where cargo and debris removal and some cutting operations may continue.
At the end of April divers were able to re-enter cargo hold four and start removing debris to assess the partially intact container of beads located. Remaining 18 containers in the bow are empty and have disintegrated in the hold. Of the original 1,368 containers on board, 1007 have been recovered. Of the 361 that have not been recovered, 58 have been located, with the rest (303) still in the wreckage of the hull or lying unidentified in the debris field.
