A development of the Felixstowe F5L flying boat of the World War I, variants of the PN were built for the United States Navy by Douglas, Keystone and Martin.

At the end of World War I the United States Navy was operating the Curtiss H.16 and the Felixstowe F5L Long-range patrol flying boats, which had been developed in collaboration with the British.

The four PN-11s had a new metal hull with a round turtle deck and lacking the previously characteristic enlarged chines and had a new empennage with twin fins and rudders.

These also formed the basis for the Hall PH flying boats, with a different hull fitted with an enclosed cockpit, and some of these remained in service until World War II.

During the afternoon of 31 August 1925, an attempt was made to fly a pair of PN-9 planes non-stop from San Francisco to Hawaii, a distance of nearly 2,400 miles (3,864 km) — a trip anticipated to take 26 hours to complete.

[5] The first plane to start was forced to land 300 miles (480 km) outside of San Francisco due to a failure of oil pressure, with the crew rescued by the destroyer USS William Jones and the aircraft towed back to port.

[5] The second PN-9 to depart, captained by U.S. Navy Commander John Rodgers, flew 1,841 miles (2,963 km) before running out of fuel when anticipated tailwinds that would have slowed gasoline consumption did not materialize.

[5] The plane was unable to make contact with the naval airplane tender USS Aroostook, a ship stationed along the PN-9's flight path and was forced to land at sea when both engines stopped functioning.

[5] Although this was at the time a new distance record for seaplanes, the plane remained hundreds of miles short of the nearest landfall and the situation of the crew, with limited quantities of food and water, appeared dire.

1, the same plane sailed to Hawaii, did not fare as well, later ditching in the Caribbean Sea during an attempted long-distance flight to South America and subsequently sunk as a navigation hazard.