INS Betwa was salvaged to its upright position using complex hydrodynamic calculations and rigging, the Indian Navy said on Thursday.
The guided missile frigate slipped while undocking at the Naval Dockyard in Mumbai on December 5, 2016 and, according to an Indian Navy statement, the initial stabilitsation of the ship was achieved on December 29.
After that, on January 16 a contract was signed with Resolve Marine to set the ship upright.
"The Indian Navy is confident that with in - house expertise and sustained efforts, the ship will be made fully operational by her scheduled date of refit completion, which is by April 2018, " the statement said.
The process employed to get the ship on even keel involved "complex hydrodynamic calculations and rigging up of intricate measuring and monitoring systems", the statement said.
As the ship was undergoing major refit and mid - life up - gradation since April 2016, majority of the equipment and machinery had already been removed for routine servicing and replacement with upgraded equipment.
The vessel was undergoing a refit at the dry dock in the naval dockyard in Mumbai when it slipped during undocking, or the process of re - floating a ship back in water, on December 5, killing two naval personnel and injuring 14 others.
The frigate slipped from her dock blocks and tilted.
Officials initially said it appeared that the dock block mechanism had failed.
A Board of Inquiry headed by Flag Officer, Offshore Defence Advisory Group, Rear Admiral Deepak Bali was ordered to look into the incident.
INS Betwa - - inducted in the navy in July 2004 - - was part of Task Force 54, tasked to evacuate nationals of India as well as those from Sri Lanka, Nepal and Lebanon married to Indian nationals from the conflict zone during the 2006 Lebanon war, as part of Operation Sukoon.