The searching effort started on Sunday led by Head of Search and Rescue Agency M Syaugi and Head of Simalungun District JR Saragih.
The sonar scanning can be used to search for an object in a depth of 2,000 meters.
The Head of Medan SAR, Budiawan, said they also operated another sonar equipment that can search in the depth of 600 meters.
"It is important to find the location of the vessel. We predict there are still victims inside the boat," Budiawan said.
At least 183 persons are still missing after the Sinar Bangun MV sank on June 18.
The SAR agency also operated Dauphin A 365 helicopter to assist the search and help the evacuation.
Several personnel also searched the victims in the coastal area.
The SAR team also used 17 inflatable boats and speed boats to search for the victims within a radius of 40 kilometers.
Previously, the SAR team has found 19 survivors and three dead passengers.
Reporter: Bayu Prasetyo
Editor: Suharto
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