Rupertus, again homeported at Long Beach, arrived there on 3 August 1966. A year later, she sailed for the Far East again, arriving on "Yankee Station" in the Gulf of Tonkin in July. With when a series of explosions temporarily disabled the carrier on 29 July, Rupertus maneuvered to within of the crippled ship and remained alongside for a period of three hours, assisting in fighting fires, cooling magazines, and rescuing personnel thrown into the sea. Rupertus then participated in "Sea Dragon" operations, involving the interdiction of waterborne logistics craft staging from North Vietnamese ports, and drew enemy fire off Đồng Hới, North Vietnam, which resulted in minor shrapnel hits. Assigned to gunfire support off South Vietnam in October, she returned to Long Beach on 4 December.
