of the superstructure that connects the lower tank deck with the main deck and a passage large enough to allow access to the parking area amidships. The vessels are also equipped with a stern gate to allow the unloading of amphibious vehicles directly into the water or to unload onto a utility landing craft (LCU) or pier. At either end of the tank deck there is a turntable that permits vehicles to turn around without having to reverse. The Newport class has the capacity for of vehicles, of cargo area and could carry up to 431 troops. The vessels also have davits for four vehicle and personnel landing craft (LCVPs) and could carry four pontoon causeway sections along the sides of the hull. Frederick was initially armed with four Mark 33 /50 caliber guns in two twin turrets. The vessel was equipped with two Mk 63 gun control fire systems (GCFS) for the 3-inch guns, but these were removed in 1977–1978. The ship also had SPS-10 surface search radar. Atop the stern gate, the vessels mounted a helicopter deck. They had a maximum complement of 213 including 11 officers. Construction and career United States Navy service The ship was ordered as part of a group of eight ships in Fiscal Year 1966. The LST was laid down on 13 April 1968 at San Diego, California, by the National Steel and Shipbuilding Company. Named for a city of city and county in Maryland, the vessel was launched on 8 March 1969, sponsored by Mrs. Kleber S. Masterson. Frederick was commissioned into the United States Navy on 11 April 1970. Following shakedown, Frederick was assigned to the Amphibious Force, Pacific Fleet, and was homeported at San Diego. She made over thirteen major deployments to the Western Pacific and Far East. Frederick earned one award of the Meritorious Unit Commendation and three battle stars for Vietnam service. Frederick was decommissioned on 5 October 2002. Mexican Navy service Frederick was sold to Mexico as part of the Security Assistance Program on 9 December 2002 and was commissioned into the Mexican Navy as ARM Usumacinta (A 412) the same day. The ship was struck from the United States Naval Vessel Register on 6 November 2002. In 2012 ARM Usumacinta, along with a Naval Infantry detachment, took part in the large multi-national naval exercise RIMPAC 2012 off the coast of the Hawaiian Islands. The ship also