paddlewheels

Paddlewheels are large, rotating propulsion wheels consisting of a circular hub with evenly spaced paddles attached to the rim, used on watercraft to push water backward and generate forward thrust. They come in two main configurations: side-wheelers, which mount one or two wheels on the sides of a hull; and stern-wheelers, which place a single wheel at the stern.

Operation: An engine—historically steam engines, later diesel or electric—turns the wheel via a gearing system. As the wheel rotates, its paddles scoop water and fling it backwards, creating thrust. Paddlewheels are most effective at low speeds and in shallow water, offering good thrust at minimal draft, but are less efficient than propellers at higher speeds and can be more susceptible to damage from debris.

History: Paddlewheels were among the early practical means of propulsion for inland and river steamers in the 19th century, enabling reliable service on the Mississippi and other major river systems. Side-wheelers and stern-wheelers dominated U.S. river transport, while Europe and Asia used similar designs on smaller craft. The development of screw propellers in the late 19th and early 20th centuries reduced their military and commercial prominence, though many paddlewheelers were preserved or repurposed as tourist craft.

Modern usage: Today paddlewheels survive mainly on heritage vessels and entertainment craft, where they serve historical demonstration and sightseeing roles. They remain a symbol of early river transport and steam power.