The removal of second piece of Rena's 700-tonne accommodation block has been put on hold as a result of the ship's stern moving during Cyclone Lusi.
However, salvors are preparing for the removal of a 600-tonne port side piece of the wreck.
The first piece of the accommodation block was cut and lifted from its location on Astrolabe Reef almost two weeks ago. It was initially thought the second piece of the accommodation block could be lifted from the wreck after divers had a clear seven-day window to survey and reset the lifting chains on the new piece.
Last week divers noticed the position of the Rena's stern had changed after Cyclone Lusi and spokesman for Rena's owner and insurer Hugo Shanahan said they would not progress with the second cut and lift of the accommodation block until an underwater sonar survey could be completed on the wreck.
He said it was something they had to do before they could make any decision to move forward.
"The underwater sonar survey has been commissioned to secure a 3D computer model of the ship's position to confirm the extent of the movement and any effect this may have had on the structure."
The high-end piece of sonar equipment is being brought in from the United Kingdom.
The remaining bow section would also be surveyed over the next few weeks and a new operations plan would be devised after that.
Mr Shanahan said the survey should be completed by mid-April and salvors would remain busy in this time with preparations to remove the 600-tonne port side piece.
"This port side piece broke away from the major aft section, which is what the accommodation block is connected to," he said. "It's estimated that it will take 19 days to cut and lift this piece in three sections on to RMG 1000 (barge) before it can be brought ashore."
Captain John Owen, senior claims manager for Rena insurer The Swedish Club, said the survey would help clarify any updates necessary to the assessment information of their resource consent application to leave the wreck on the reef.