Ghazi's existence was revealed when signal addressed to naval authorities in Chittagong was intercepted, requesting information on a lubrication oil only used by submarines and minesweepers.
Though we don't have enough ships to escort the aircraft carrier in the Bay of Bengal,the very profile of the Ganges Delta which is shallow gave enough confidence that it was too shallow to support a submarine for about 50 miles or so. So it was decided that aircraft carrier will travel only in this area. It was clearly caliculated that the submarine has to get at her it will have to surface, because it cannot stay down in shallow waters. so vikrant sailed with only two ships as escorts. 

At the same time concerted action was taken to disseminate information designed to mislead the enemy about the true location of the aircraft carrier, and to foster confidence that the carrier was stationed at Visakhapatnam.
Contracts were placed for delivery in Visakhapatnam of large quantities of food, especially meat and fresh vegetables, allegedly destined for the Eastern Fleet ships. A private telegram was allegedly sent from Vishakhapatnam from one of the sailors of the aircraft carrier, inquiring about the health of his ailing mother. All these activities were apparently successful in deceiving the enemy. 25 November, the Pakistani command sent communication to the Ghazi saying that "intelligence indicates the finding of an aircraft carrier in port".

On December 3, they thought the Vikrant was still at Vizag because we had worked up a lot of fake wireless traffic, about requiring supplies that could only be meant for a carrier, out of Vizag.

With all the ships sailed to Andamans and it was INS Rajput the lone ship that is keeping the vigil over the waters of Vizag. In narrow channels, ships, during an emergency or war, always throw depth charges around them to deter submarines. INS Rajput just did that and One of them hit the Ghazi. The blow-up was there, but nobody knew.

It was a fisherman who discovered a lifejacket which had 'Made in America' written on it. At that time there was only one ship in harbour, the Rajput which needed some repairs. All the others had sailed to the Andamans. She left a few days later, about 8 in the evening or so. After an investigation about the location where the life jacket found and a deep water diving exercise have got the news that it was INS Ghazi and the log book was still on display in the navel museum.