A 250 tonne chunk of Rena has broken off and fallen into the sea taking vital salvage equipment with it.
The 25m length of steel ripped off the main body of the Rena wreck in high winds and rough seas this week. The piece is considered one of the heaviest parts of the ship.
No one was on board at the time but salvors' gas cutting tools worth tens of thousands of dollars were lost.
The salvage company says the broken piece of Rena poses no environmental risk, as every trace of oil had been removed.
Frank Leckey, senior salvage master for Resolve Salvage and Fire, said he expected to retrieve the equipment and the piece off the Rena, which lay in the water off Astrolabe Reef.
"We will have to put divers in the water and get a crane to retrieve the stuff."
Mr Leckey anticipated the piece of steel would be cut into four sections then lifted out and removed.
The broken piece could be seen lying beneath the water alongside the ship yesterday.
The colour of the water surrounding it indicated its sloping depth, one part breaking the water's surface.
Mr Leckey said his crew had been preparing to cut the aft side of the ship, which was "dangling away at the back" and had placed their equipment on a makeshift platform near the loose section of the Rena before poor weather set in. "Of course our equipment went with it."
Although the incident had delayed salvage operations by a day and the retrieval would cost more money, it had not impinged greatly on the operation, Mr Leckey said.
Already about 400 tonnes of steel had been removed and things were on track to be completed by December, he said.
Salvors were removing the section of Rena that remained above the water but cutting pieces off one by one.
Mr Leckey said his crew had to wear life-harnesses while working.
"When it's rough, the actual Rena moves. It sways and rocks and rolls and is kind of unstable."
Yesterday, the ship appeared to have given up its fight, lying across the reef.
Where white surf once lashed up against the pierced hull, calm water eased through gaping holes.
The word Rena remains steadfast on the side of the hull, but the rest of the ship resembles a decaying body. The former white inner walls are yellowed and rusted.
Grime can be seen where the sea water rests inside the body and the gashes where metal has been cut leave the ship looking more like a broken Lego piece instead of the impressive 236m cargo ship of 11 months ago.
News of the chunk falling into the sea comes in a week where the captain, Mauro Balomaga, and navigation officer, Leonil Relon, were released from prison after serving just half of their seven-month sentences.
The men were jailed on May 25 for charges under the Resource Management Act 1994, Maritime Transport Act 1994 and Crimes Act 1961 but were deported back to the Philippines on Thursday, their jobs still waiting for them.