Jamie Morton is the NZ Herald's science reporter.

Rena salvage job continues

The stricken ship Rena on the Astrolabe Reef off the coast of Tauranga. File photo / Bay of Plenty Times
The stricken ship Rena on the Astrolabe Reef off the coast of Tauranga. File photo / Bay of Plenty Times

One of the most lengthy, tricky and costly ship salvage jobs in history is dragging in the Bay of Plenty, as the team working on the wrecked container ship Rena prepare to cut and remove the vessel's submerged accommodation block next month.

The block is a large feature of the sunken stern section, which lies wedged at a 55 degree angle to starboard down to a depth of 65 metres on the eastern side of Astrolabe Reef, off the Tauranga coast.

The Rena has remained stuck on the reef since it grounded there on October 5, 2011, spilling 350 tonnes of heavy fuel oil into the sea.

Specialist salvage divers of Resolve Salvage and Fire have the main responsibility in the overall scheme of the project, which involves burning rigging holes and clearing internal pathways to enable approximately 2000 metres of large industrial three inch wire chains that will effectively slice the house into two 350-tonne blocks.

In the last week, divers have been preparing a B-Deck starboard aft chain path, which involves removing internal structures such as pipework, creating vents to allow gases to escape and marking out and burning holes to eventually feed the wire cutting chains through.

Rigging holes are also being burnt to install specialist protector equipment used during the lift operation.

Diving on this task has been at depths of approximately 46 metres, while other diver preparations have involved cutting down and removing major protruding features such as the large funnel, which will reduce drag and weight once the lift operation starts.

Once cut, the two sections will be lifted onto a second barge to be transported to port where they will be dismantled for scrap and, where possible, recycling.

A team of small craft will be stationed at the reef to collect any debris released during the operation.

The entire operation - a logistical nightmare which has involved a race to pump Marmite-like oil from fuel holds and cranes plucking away containers stacked in high leaning towers - has now reached the point where nothing of the Rena is visible from above the water.

At the last estimate, the cost of the disaster and salvage to the owners had hit $300 million, making it one of the costliest salvage jobs in history.

Meanwhile, the ship's owners still haven't made a call on whether they will seek to leave all or part of the remaining wreck on the reef.

Assessments of the wreck's environmental, social and cultural impacts are due to be complete by the end of the year, and until then the owners say any decision to lodge a consent application won't be made.

- NZ Herald

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