A 350 tonne bridge section of the former container ship Rena lies on the seafloor near Motiti Island today as salvors attempt to re-rig the crane barge's lifting blocks for another lift.

The section was carried to the eastern side underwater, suspended from the crane barge RMG 500 that cut and lifted the section from the back end of the sunken wreck at Astrolabe Reef earlier this week.

Resolve Salvage and Fire have been working to lift the section clear of the water and place it on the accompanying deck barge RMG 1000 for cutting up.

But spokesperson for the ship's owners and insurers, Hugo Shanahan, says the chains securing the section shifted during the operation, preventing salvors from lifting the section high enough from the water to get the second barge underneath.

It is now lying in about 35 metres of water east of Motiti Island where it will be re-rigged for the lift.

Roger King, a consultant with TMC Marine Consultants London, describes the operation as a 'Four-D” problem; it's difficult, dangerous, deep, and there are lots of delays.

The salvage has continued since the former container ship struck the Astrolabe Reef on October 5, 2011.

The latest chapter involves cutting the ship's six-storey accommodation block off the rear of the hull, now lying in water up to 50 metres deep on the north eastern face of the reef.

The wreck's owners and insurers say because it is made of lighter gauge steel than the hull, the ‘house' represents a pollution threat as it decays, and is being removed.

They also stated previously that removing the accommodation section opens easier access to the ship's rear hold, which will make clearing container and cargo debris easier.

The owners and insurers are on record saying once the current salvage and clean-up is complete, they want to leave the remainder of the wreck on the reef.