The nickname used for Ford’s amphibious jeep, the GPA, was “Seep.” The name is a contraction of “Sea Jeep,” reflecting the vehicle’s attempt to combine the familiar light Jeep with amphibious capability.
Ford produced the GPA during World War II, primarily in 1942 and 1943. Its designation meant Government, “P,” Amphibious, while the “P” also related to the vehicle’s short wheelbase classification. More than 12,000 were built and supplied to Allied forces, including through the Lend-Lease program.
The GPA used a watertight hull, a propeller, and four-wheel drive, allowing it to travel on land and cross calm water. However, it was heavier and less seaworthy than planners hoped, with low freeboard that made rough water hazardous. This is why it is often contrasted with the larger and more successful DUKW amphibious truck.
“Seep” is sometimes confused with “Duck,” but “Duck” was the common nickname for the DUKW, not the GPA. After the war, the Soviet GAZ-46 was developed partly from GPA experience.