What propulsion does the DUKW use in water?

The DUKW uses a propeller for propulsion in water. Its truck engine drove the propeller through a power take-off, transfer case, and propeller shaft, while a rudder helped steer the vehicle afloat.

The DUKW was created during World War II by combining the chassis and mechanical systems of a GMC CCKW 2½-ton truck with a watertight boat-shaped hull. That arrangement allowed it to drive normally on land and then enter the water without being loaded onto a separate landing craft.

The wheels remained important in water as well as on shore, but they were not the main means of aquatic propulsion. The vehicle’s selectable propeller system supplied thrust, while the truck’s six-wheel-drive system provided traction when climbing beaches or crossing soft ground.

People sometimes confuse the DUKW with tracked amphibious vehicles such as the LVT, or imagine that its wheels acted like paddles. They did not: the DUKW was a wheeled truck with a dedicated propeller. More than 21,000 were built between 1942 and 1945, and surviving examples later became popular tourist vehicles.