Ford GPA

The Ford GPA 'Seep' (from Seagoing Jeep), was an amphibious version of the WWII Ford GPW Jeep. Unlike the jeep, the seep was not a successful design being too slow and heavy on land and lacking sufficient seagoing abilities in open water. Similar design features were used in the larger and more successful DUKW amphibious truck.


History and development

After having commissioned Willys, Ford and Bantam to build the first 4,500 jeeps (1500 each) in March 1941, the US Motor Transport Board set up a project under the direction of the National Defense Research Committee (NDRC) to be designated "QMC-4 1/4 Ton Truck Light Amphibian".


The War was on at full tilt, and with bridges over Europe's rivers being taken out one after another, it seemed practical if the jeep could swim as well as drive. And so it came to Roderick Stephens Jr. of Sparkman & Stephens Inc. yacht designers, to design a shape for a 2700 lb (1,200 kg) amphibious jeep, in the same vein as his earlier design for the DUKW six-wheel-drive amphibious truck. Not surprisingly Stephens' hull design looked like a miniature version of that of the DUKW, and just like it, the 'Seep' was going to have a screw propellor, driven by a power take-off, operating in a dedicated tunnel spared into the rear end bodywork, as well as a proper rudder.

Ford GPA Sea jeep. The Army's most flexible new machine of the war, a Ford-built amphibian reconnaissance car, carrying soldiers equipped for combat duty takes to the water in special tests staged recently in the Detroit area. This picture shows how the new transportation arm propelling itself as a boat to the opposite shore. The boat steers in the water the same as on land.

The construction of the vehicle was developed in competition by Marmon-Herrington and Ford Motor Company. The Marmon-Herrington prototype's hull formed an integral unibody structure, created by cutting shapes out of steel plate and welding those together, much like the hull or chassis of an armoured vehicle. The Ford entry however used a sturdy chassis and internal frame, to which more or less regular automobile type sheet-steel was welded. This construction made the GPA some 400 lb (180 kg) lighter than its competitor. Also The GPA's design was based on the Willys MB and Ford GPW standard Jeeps as much as possible. When designing and building the GPA, Ford utilized many of the exact same parts that the Ford GPW did. The GPA had an interior similar to that of the MB/GPW jeeps, although the driver's compartment had almost twice as many control levers: 2WD/4WD, hi-range/lo-range, capstan winch (on the bows), propeller deployment and rudder control. After a direct comparison of the two company's prototypes, Ford received a contract for production starting in 1942.

Ford GPA amphibian jeeps at factory in Detroit, Michigan, awaiting truck transport, April 1943.

Service

In contrast to the DUKW the GPA (G=Government, P=80" wheelbase, A=Amphibious) did not perform well in the field. At some 1,600 kg the production craft had become much heavier than the original 1,200 kg specified in the design brief, but its volume had not been increased accordingly. As a consequence a low freeboard in the water meant that the Seep couldn't handle more than a light chop, and certainly couldn't take much cargo. The Seep's intended objective: to ferry soldiers to and from ships off-shore, to trundle up the beach and continue inland, was therefore not met. It is reported that many of the Jeeps that were used in battle sank if there were any significant waves at all.

War time US Army photo of a an early Ford GPA made in 1942.

On land the vehicle was too heavy and its body too unwieldy to be popular with the soldiers. Adding insult to injury, the GPA would frequently get stuck in shallow waters, where the regular Willys MB's water fording abilities allowed it to drive straight through (Pohl, 1998). Production was already halted in March 1943 after production of only 12,778 vehicles, due to financial quibbles between Ford and the US government, as well as bad reception of the vehicle in theatre. Although some sources state that less than half of that number were ever completed, serial numbers of surviving specimens suggest that the 12,7XX figure is actually correct.


In spite of participating successfully in the Sicily landings of September 1943, and performing reasonably well in inland river crossings, most GPA’s were routed to Russia under the Lend-Lease program.


Postwar

The Russians were sufficiently pleased with the GPA's ability to cross rivers and inland waters, to keep developing it after the war. Starting out with the chassis of the GAZ-67B, prototypes were created that largely copied the Seep's layout and design, eventually leading to the GAZ 46 MAV, based on the chassis and mechanicals of the GAZ 69 4x4 jeep, to go into production as of 1952. Both the GAZ 69 and the amphibious GAZ 46 were exported to many communist countries.

Half Safe leaving New York in August 1948.

Half-Safe

During the 1950s Australian Ben Carlin (1912–1981) sailed and drove a modified Seep, that he called "Half-Safe" on a journey around the world.

Ford GPA at the South African National Museum for Military History.

Ford GPA 'Seep' (Sea Jeep)

Manufacturer Ford
Production 12,778 (1942–1943)
Assembly United States
Class Amphibious military utility vehicle
Layout front-engine RWD / 4x4
Platform Ford GP
Engine(s) 4-cyl. side valves, 134 cu.in (2,199 cc), 60 hp
Transmission(s) 3-speed + 2-speed transfer case;
low range engages FWD;
PTO propellor drive
Wheelbase 84 inch / 213 cm
Length 182 inch / 462 cm
Width 64 inch / 163 cm
Height 69 inch / 175 cm; 45 inch reducible
Curb weight 3,665 lb / 1,630 kg; (GWV 4,565 lb / 2,030 kg)
Related GAZ 46 (MAV)

Interior of the Ford GPA at the South African National Museum for Military History.