Promotion In the United States Navy, promotion to lieutenant is governed by United States Department of Defense policies derived from the Defense Officer Personnel Management Act (DOPMA) of 1980. The United States Coast Guard follows the same policy regarding promotion to lieutenant. DOPMA guidelines suggest that at least 95% of lieutenants (junior grade) should be promoted to lieutenant after serving a minimum of two years at the lower rank. In the Royal Navy, promotion to lieutenant is done in line with seniority. Officers are typically promoted after serving as a sub-lieutenants (OF-1) for 30 months. However, promotion may be quicker if a candidate has previous naval service and commissions from the ranks (upper yardsman/senior upper yardsman). "First lieutenant" in naval usage The first lieutenant (1st Lt or 1LT) in the Royal Navy and other Commonwealth navies, is a post or appointment, rather than a rank. Historically, the lieutenants in a ship were ranked in accordance with seniority, with the most senior being termed the first lieutenant and acting as the second-in-command. Although lieutenants are no longer numbered by seniority, the post of "first lieutenant" remains. In minor war vessels, destroyers and frigates, the first lieutenant (either a lieutenant or lieutenant commander) is second in command, executive officer (XO) and head of the executive branch; in larger ships, where a commander of the warfare specialisation is appointed as the executive officer, a first lieutenant (normally a lieutenant commander) is appointed as his deputy. The post of first lieutenant in a shore establishment carries a similar responsibility to that of the first lieutenant of a capital ship. In the U.S. Navy or U.S. Coast Guard, the billet of first lieutenant describes the officer in charge of the deck department or division, depending on the size of the ship. In smaller ships that have only a single deck division, the billet is typically filled by an ensign; while in larger ships, with a deck department consisting of multiple subordinate divisions, the billet may be filled by a lieutenant commander. On submarines and smaller Coast Guard cutters, the billet of first lieutenant may be filled by a petty officer. Rank insignia The insignia of a lieutenant in many navies, including the Royal Navy, consists of two medium gold braid stripes (top stripe with loop) on a navy blue or black background. This pattern was copied by the United States Navy, the United States Coast