sea appointment and in June 1949 was appointed gunnery officer of the Black Swan-class sloop , commanded by Commander Bhaskar Sadashiv Soman. He served on the Jumna for eighteen months. In January 1951, he was posted to the newly established Gunnery school in Cochin as an instructor. He was promoted to acting rank of lieutenant commander on 30 June 1952. Later that year, he was selected to attend the Defence Services Staff College, Wellington. After completing the staff course, he was appointed staff officer (gunnery) at Naval headquarters on 25 August 1953. He was promoted to substantive lieutenant-commander on 25 November 1953. Pereira led the naval marching contingent during the Republic Day parade on 26 January 1954. In December 1954, he was appointed gunnery officer and flotilla gunnery officer of the Black Swan-class sloop INS Cauvery (U10) and in March 1955, of the Navy's first cruiser – the Leander-class cruiser . Delhi was under the command of Captain Benjamin Abraham Samson. In May 1956, he took over as officer-in-charge (OIC) of the Gunnery School, Cochin. Later that year, he was promoted to the acting rank of commander. Pereira was promoted to the substantive rank of commander on 30 June 1958, and in October was appointed executive officer of INS Delhi, stationed at Bombay. He was to have a short stint as XO of Delhi, since he was diagnosed with tuberculosis and was hospitalised in February 1959. He recovered in about ten months and was appointed OIC of DEMOB centre at Bombay. In May 1961, he was appointed XO of the shore establishment . This also included the responsibility of the naval barracks at Bombay. On 18 April 1962, Pereira was appointed commander of the 14th frigate squadron and commanding officer (CO) of the Blackwood-class Anti-submarine frigate . Apart from Kuthar, the squadron consisted of and . Pereira was considered by the then Flag Officer Commanding Indian Fleet (FOCIF) Rear Admiral Adhar Kumar Chatterji as the best all round CO in the Indian Fleet and considered him suitable for higher sea-going commands. In June 1963, Pereira was posted to Bombay as the drafting commander, tasked with the planning of expanding manpower requirements for operational and administrative efficiency of the navy. After an eighteen-month stint at Bombay, he was appointed director of weapon policy & tactics (DWPT) at Naval HQ in December 1964, with the acting rank of captain. He served in