Weather hampers salvage of Rena

Aluminium ingots are among the debris on the seabed.

Salvors now need to use specialist dive equipment to reach part of the Rena wreck which has sunk to a depth of between 65 to 68m.

David Billington, Maritime New Zealand's (MNZ) response and recovery manager, said Cyclone Lusi resulted in a significant change in the form of the ship which had made the salvage operation more technically challenging and hazardous.

"Every time there is a bad weather event Rena further breaks down which compounds the problem," he said.

Removal of the second piece of Rena's 700-tonne accommodation block was put on hold as a result of the ship's stern moving further down the reef during the cyclone.

Mr Billington said the front part of the wreck was down in a depth of between 7m and 30-35m, while the back end of the stern was down about 65-68m, requiring highly specialised diving equipment to reach. A team of 45 salvors was involved in the salvage operation, including a group of divers, he said. "It is fair to say there is multi-million dollars worth of assets and resources associated with this salvage operation," he said.

That included using two big heavy lifting cranes, a hydraulic grab to recover debris, heavy lifting helicopters, several barges and a team of salvors.

He described the estimated 3000 tonnes of debris on the seabed as looking like a "car junk yard".

Among the debris field between the bow and aft sections is scrap metal, rubber tyres, wiring, aluminium ingots, some bags of magnesium oxide and several tonnes of plastic beads.

There were 1368 containers on board at the time of the grounding. In total, 1053 containers had been recovered or accounted for but 315 remained unrecovered. That included 281 among the debris field, 32 containers on the seabed close to the ship. Two others were also located on the seabed but could not be identified due to damage. Mr Billington said the majority or 1300 tonnes of steel had been removed from the front section of the wreck. But, an estimated 11,000 tonnes of steel still needed to be recovered.

The removal of the Rena was always going to be done in a staged process and required taking large bite-sized chunks to "eat" away at the metal frame of the wreck. Once brought to the surface, the debris was sorted and taken to shore for recycling or disposal.

"I can understand why people are upset and concerned about the boat still being on the reef. But the Crown, MNZ, the salvors and The Swedish Club [the insurers] are doing all we can to remove it as fast as we can. But, the salvage operation is weather-dependant and also subject to strict health and safety guidelines." Last month the Waitangi Tribunal heard evidence from representatives from three Motiti Island iwi and hapu groups about the Crown's conduct after the Rena's grounding. They called on the tribunal to support their calls for the ship to be removed, despite Rena's owner lodging a resource consent application to leave sections of the wreck in place on Otaiti (Astrolabe) Reef. The Tribunal is expected to release preliminary findings on Thursday.