The U.S. Navy was established by vote of the Constitutional Congress in 1775, but it was not until 1798 that the U.S. Department of Navy was founded. Throughout it feats in battles around the globe, the Navy has been shrouded in tradition and custom. Many of those customs, including the way in which naval vessels are boarded continue in modern-day military life. Boarding a vessel necessitates adherence to certain protocol regarding the U.S. flag and the officer of the deck (OOD).
Prepare to board the Navy vessel by locating the ensign (flag) and the officer of the deck (OOD). The ensign is generally flown at the fantail of the ship. The OOD could be standing at the gangway or on board the vessel.
Salute the ensign. The salute is always done in uniform (by Navy officers and personnel, as well as personnel and officers of all other branches of the U.S. armed forces) and is achieved by standing at attention with feet together and raising the right hand with fingers and thumb straight and touching the bill of the hat or the temple above the right eye, with upper arm extended parallel to the ground. Non-uniformed members of the U.S. armed forces pause before the ensign and stand momentarily. Civilians have no duty to salute, but may follow the protocol for non-uniformed members of the armed forces and pause before the ensign.
Salute the officer of the deck (OOD). Members of any of the branches of the armed forces must salute the OOD only after halting, saluting the ensign and then turning toward the OOD. Civilians do not have a duty to salute Navy officers.
Request permission to board the vessel. After saluting the OOD, military personnel must say, "Sir [Ma'am], I request permission to come on board." If the vessel is not your vessel, add the purpose of the visit by stating, for example, "to visit a friend."
Walk aboard only after being given permission by the officer of the deck (OOD). Come aboard after receiving permission from the OOD in the form of a "come aboard" or in other similar words.