A ship sponsor, by tradition, is a female civilian who is invited to "sponsor" a vessel, presumably to bestow good luck and divine protection over the seagoing vessel and all that sail aboard. In the United States Navy

United States Navy

The United States Navy is the naval warfare service branch of the United States Armed Forces and one of the seven uniformed services of the United States. The U.S. Navy is the largest in the world; its battle fleet tonnage is greater than that of the next 13 largest navies combined. The U.S...

 and the United States Coast Guard

United States Coast Guard

The United States Coast Guard is a branch of the United States Armed Forces and one of the seven U.S. uniformed services. The Coast Guard is a maritime, military, multi-mission service unique among the military branches for having a maritime law enforcement mission and a federal regulatory agency...

the sponsor is technically considered a permanent member of the ship's crew and is expected to give a part of her personality to the ship, as well as advocate for its continued service and well-being.