Scores of people are feared dead after a ferry capsized off the coast of south-east Indonesia on Thursday.
Fifteen people survived, but four days after the disaster rescue teams said they did not expect to find any more people alive.
The ferry was officially carrying 35 passengers and 15 crew, but witnesses have said that up to 200 people were on board.
Boat accidents are common in Indonesia, due to overcrowding and poor safety.
"From our experience, when we reach the fourth day of rescue, there is a big chance we will not find any survivors," Sumpeno Juono, head of a local rescue agency, told Reuters news agency.
"If possible, we will flip the ferry into normal position so that the evacuation process can become easier," he said.
The ferry sank in rough seas hours after leaving Merauke, in the province of Papua, on its way to the town of Tanah Merah.
Mr Juono said the ferry left Merauke - 3,800km (2360 miles) east of the capital, Jakarta - carrying vehicles, heavy equipment and diesel oil.
He said the ship did not have any safety equipment.
Rescue operations have been hampered by heavy rains and 4m-high (13ft) waves.