The fire on board the submarine INS Sindhuratna could have started from the sailors' deck above the battery pit of the vessel, Navy said on Tuesday.
"A preliminary assessment of damage sustained onboard was carried out by a specialist team of Western Naval Command. Based on preliminary inspection of third compartment (sailors' accommodation), the likely seat of fire has been indicated as the mess deck, which is located one deck above the battery bit," a Navy release said.
Certain electric cables were observed to be "burnt in this area and the cause for initiation of fire at this location would be ascertained in due course by the high level Board of Inquiry".
On the status of batteries, the Navy said Kilo Class submarines carry 240 cells, distributed equally in forward and aft battery pits.
The batteries currently "installed on Sindhuratna have till date completed about 113 cycles as against 200 cycles available for exploitation... The batteries which were being exploited by Sindhuratna at the time of incident were therefore operationally in-date," it said.
On the status of the battery compartment in the vessel, the Navy said, "Preliminary inspection shows no damage has been observed thus for. Further, there are no signs to indicate any initiation of fire from the battery pit. The batteries appear to be clear of any damage and would now be put through normal checks and maintenance routines prior operationalisation."
Image: INS Sindhuratna docked at the naval base in Mumbai
Photograph: Sahil Salvi