Ford GPA

The Ford GPA, popularly known as the Seep ("sea jeep") or amphibious Jeep, was a Second World War amphibian inspired by the much larger DUKW. The designation stands for G (Government), P (80-inch wheelbase) and A (Amphibian). It was intended to carry soldiers between ships offshore and the beach and then continue inland.

Design

The GPA was essentially the standard wartime Jeep chassis wrapped in a simple boat-shaped hull. A propeller in a tunnel at the rear was driven from a power take-off on the transfer case, while the drive shafts to the front and rear axles ran in waterproof tubes sealed to the hull and differentials with flexible gaiters to allow suspension movement. The engine was the standard Jeep 2.2-litre four-cylinder side-valve unit with minor changes, with a three-speed gearbox and two-speed transfer case giving part-time four-wheel drive.

The driver faced an array of levers for two- or four-wheel drive, high and low range, the propeller, the rudder and a capstan winch on the bow, which was driven by a pulley from the engine. Data plates on the dash advised on tyre pressures and on entering and leaving surf. Engine air came through a hatch in the front deck that could be closed in rough water, though the engine would then slowly overheat, and a surf shield could be swung forward to stop waves sweeping over the bow. Later GPAs carried a Danforth anchor, and the rear seat lifted to reveal tools and the two 6-volt batteries. The vehicle was about 4.6 m long and 1.6 m wide, seated four and weighed around 1,650 kg unladen.

Service

The GPA was not a great success. According to sources quoted in the archive, 12,000 were planned but only about 5,000 were built, all by Ford, and many used in action reportedly sank in any significant waves. Nevertheless a heavily modified GPA named 'Half-Safe' crossed the Atlantic in 1950 and went on to circle the world. Surviving examples are prized by collectors; one restored 1943 GPA in Western Australia was sold in 1995 and later advertised in Sydney.