The Hall PH was an American flying boat of the 1930s. It was a twin-engined biplane, developed from the Naval Aircraft Factory PN and could hence trace its lineage back to the Felixstowe flying boats of World War I. The PH was purchased in small numbers by the United States Navy and the United States Coast Guard. It remained in service with the Coast Guard until 1944, being used for anti-submarine and search and rescue duties.
Delivery of the PH-1 commenced in October 1931, equipping VP-8 from 1932, operating from the seaplane tender Wright and from bases at Pearl Harbor, Midway Atoll, and the Panama Canal Zone. It was replaced by the Consolidated PBY-1 Catalina in 1937.
Production of the PH recommenced in June 1936 to meet an order for seven PH-2s for the Coast Guard. These entered service from 1938, being the largest aircraft operated by the Coast Guard at that time. In 1939 the Coast Guard ordered an additional seven PH-3 aircraft; they entered service in 1941.
The Hall flying boats were used by the Coast Guard for search and rescue duties and were fitted with specialized equipment for this role. Following the Japanese attack on Pearl Harbor and the United States entry into World War II, the remaining PHs were painted in U.S Navy Grey Green colors to replace the previous bare metal finish, armed, and used for anti-submarine patrols (particularly during the Operation Drumbeat U-boat attacks off the East coast of the United States in 1942) as well as continuing search and rescue operations. The Coast Guard continued operating the PH-2 and -3 until 1944.