MANUFACTURER(S): Sparkman & Stephens / General Motors Corporation (GMC) - USA
OPERATORS: Australia; Canada; France; West Germany; Philippines; Soviet Union; United Kingdom; United States
Detailing the development and operational history of the GMC DUKW (G-501 / Duck) Amphibious 6x6 Wheeled Transport Truck.
Entry last updated on 10/17/2018.
Authored by Staff Writer. Content ©www.MilitaryFactory.com.
Introduced in 1941, the 6x6 wheeled GMC CCKW 2.5-ton truck became the logistical backbone of the Allied march towards Rome, Berlin, and Tokyo during World War 2 which saw some 562,750 of the type produced into 1945. When it was realized that an amphibious version of the truck would be a sound investment for the war, a GMC initiative produced the DUKW - nicknamed the "Duck" - which sat a boat-like hull atop the CCKW's drivetrain while retaining the original 6x6 wheeled layout. Initial production of the vehicle was through the Pontiac facility in Michigan until the war required more than what was being delivered which prompted contributions from Chevrolet of St. Louis. For many, the DUKW series of amphibious trucks is regarded as one of the "war-winning" products of World War 2. Total production yielded 21,147 units before the end and many were also delivered via Lend-Lease. The Soviets appreciated the type enough to, not only use it in noticeable numbers, but also develop their own interpretation of the design.
The "DUKW" name was formed the in-house GMC nomenclature which was used to detail certain design qualities of the product through an acronym. "D" indicated the vehicle's design in 1942 while "U" showed it to be a utility-minded product. "K" indicated an all-wheel drive ability and "W" a dual-rear axle arrangement. From the DUKW acronym was generated the layman "Duck" by which the vehicles are still referred to today.
The DUKW was born in March of 1942 when the Office of Scientific Research and Development was secretly charged to design an amphibious transport that could eliminate the need to transfer ship-borne cargo to a truck upon landing on a beach. The department teamed with the Yellow Truck and Coach Division of General Motors for the work which produced a wooden mockup for review in late April. A pilot vehicle was then readied - with the hull designed by America's Cup winner Roderick Stephens - for June of 1942 and extensive testing was enacted. Upon successful completion of this phase, the truck was adopted in October of 1942 and serial production pushed to GM plants as soon as possible.
Despite this, some in the Army's ranks were not impressed with the DUKW until a December 1st night storm endangered a Coast Guard crew. Stephens took the DUKW out, with a detachment of media to document, and rescued the lads from impending doom as their ship, the "Rose" broke apart.
Because of its origins in the CCKW truck series, the DUKW was able to keep many of the strong hauling capabilities inherent in the 6x6 family. The boat-like hull only improved upon this and added an all-new feature by way of a buoyant quality. Propulsion through water sources was made possible by a single three-bladed propeller unit found at the rear of the hull with steering accomplished via a rudder arrangement aft of this propeller. The front wheels, made steerable by design, also aided some in turning the vehicle about when floating.
Power for the DUKW came from a GMC 6-cylinder 269 engine of 94 horsepower. This supplied the vehicle with a maximum road speed of 50 miles per hour with an operational range of 400 miles. Its cargo-hauling capabilities were limited to about 2.5 tons, which reduced its tactical flexibility in the grand scope of the war, and its sea-keeping ability left something to be desired when encountering rougher states than the norm but the DUKW went on to provide stellar service for its part. It is noteworthy that Ducks managed the choppy surf of the English Channel during World War 2 - that goes to say much about this vehicle.
Once on land, the 6x6 wheel arrangement kicked into gear and the vehicle moved on as a normal ground hauler. Twin axles were featured under the rear of the hull while a single axle made up the front. A central tire pressure system allowed for finer adjustment of the wheels to provide additional traction over softer terrains(such as sand on a beach). The driver was seated at front-rear in the traditional way (which meant little changed in the CCKW layout) and behind a windscreen which could be folded down for a lower profile. A cargo area made up the rear of the hull which could be covered over in canvas from the elements. The engine took its place at the front (ahead of the driver's position). A tow hook was mounted at the rear of the vehicle to help hauling loads outside of the vehicle's cargo hold capacity and a front-mounted winch could be used to pull the vehicle out of ditches and the like.
GMC DUKW (G-501 / Duck) (Cont'd)
Amphibious 6x6 Wheeled Transport Truck
The cargo hold was used to manage just about everything - twelve combat-ready troops, wounded with staff, general supplies, ammunition, and even light artillery pieces. Some artillery systems were even fired from the bed of the truck which proved useful in providing mobile firepower or assailing enemy positions on approach - particularly during an amphibious assault action. More typically, DUKWs were outfitted with medium or heavy machine guns for local, self-defense - the latter protecting against low flying aircraft as well as light armored enemy vehicles.
By design the DUKW was a transport through-and-through and originally envisioned as a supply runner for ship-to-shore work. However, it held additional strategic value in that it could go beyond shores and continue delivery of goods directly to active fronts more inland than traditional amphibious vehicles could. Of course wartime service ultimately produced official standardized and unofficial in-the-field configurations and, even then, the haste at which the vehicle was produced also led to many changes on the production lines themselves: the central tire inflation system was added in September of 1943 while the passenger's rear view mirror was lost in November of that same year. Some models also featured skirts over the wheel wells while others had their wheels completed exposed.
One of the standardized configurations of DUKW was a rocket-projecting platform which fitted a rack of 4.5" High-Explosive (HE) rockets for which to use against enemy positions upon approach of a given beach from a transport ship. This sort of suppression fire was highly appreciated and acted as much as a psychological tool against the enemy as it did a conventional battlefield weapon. Rocket-laying versions were rightly known as "Scorpions" and used heavily throughout the Pacific island-hopping campaigns. DUKWs also became veterans of the "D-Day" landings of northern France on June 6th, 1944 but its appreciation came earlier than that - during the Allied landings at Sicily (July-August 1943).
The Soviet Army became a major recipient of the classic American DUKW through Lend-Lease. Its success along the Eastern Front led to a local copy of the product emerging as the "BAV-485" though with some changes to suit Soviet service - chiefly a loading ramp was added to the rear of the hull to facilitate unloading and loading of the vehicle. As massive amphibious assaults were less in play on the Eastern Front, the vehicle was modified more for the river-/lake-crossing role than ship-to-shore work.
Beyond the Americans and Soviets, the DUKW made it into the inventories of Australia, Brazil, Canada, France, the Philippines, and the United Kingdom. The Australians operated over 500 units while the Canadians held a stock of about 800. French use ended in the early 1980s while the British, with a stock of about 2,000, ran theirs into the 1970s before giving them up for good. A select few were used by Royal Marines into 2012 however.
Many "Ducks" ended their service lives in the civilian market after the war years - the most famous use perhaps being the Wisconsin Dells "Ducks" used for touring from land to river and back.