Section 121(3) in The Naval Ceremonial, Conditions Of Service And Miscellaneous Regulations, 1964
(3)Promotion.(a)Midshipment. - On completion of 6 months' afloat training as a cadet and subject to passing the Cadet's Passing Out Examination and being recommended for promotion, cadets shall be promoted to Midshipmen.(b)Acting Sub-Lieutenants. - On completion of [6 months'] [Substitued by S.R.O. 237, dated 24th May, 1975] service as Midshipmen, and subject to passing the Seamanship Examination and being recommended for promotion, Midshipmen shall be granted the rank of Acting Sub-Lieutenant with seniority of the date on which they are promoted.(c)Sub-Lieutenants. - Acting Sub-Lieutenants shall be confirmed in rank with original seniority on the day following the successful completion of their technical courses.(d)Lieutenants. - Confirmed Sub-Lieutenants shall be appointed to sea and shall be promoted to the rank of Lieutenant at the discretion of the Chief of the Naval Staff, provide they have obtained the following certificates from their Captains:(i)that the officer is competent to take charge of a Watch at sea as Lieutenant and to perform efficiently the duties of that rank;(ii)that he is recommended and is fit in all respects for promotion to the rank of Lieutenant.Explanation. - These certificates shall not be granted before the officer has served three months at sea as a confirmed Sub-Lieutenant. No officer can, however, be promoted before the date of his seniority as a Lieutenant calculated in accordance with sub-regulation (6).