paddlewheel

Paddlewheel refers to a wheel with a series of blades that is rotated to move water and generate thrust. In boat propulsion, paddle wheels are driven by steam, internal combustion, or electric motors, and they come in two main configurations: side wheels mounted along the sides of the hull, and stern wheels positioned at the rear. As the wheel turns, its blades push water backward, producing forward propulsion. The efficiency of a paddlewheel depends on factors such as wheel diameter, blade shape and pitch, immersion depth, and the interaction with the hull.

Propulsive paddle wheels were developed in the late 18th century in Europe and North America. Early demonstrations by James Rumsey and John Fitch in the United States were followed by Robert Fulton’s successful Clermont on the Hudson River in 1807, which popularized steamboat travel. Side-wheel designs remained common on early riverboats, while stern-wheelers gained prominence on many western rivers because they handled shallow waters and debris more effectively and offered simpler steering.

Compared with certain other propulsion systems, paddle wheels offered reliable thrust at low speeds but suffered from limited efficiency at higher speeds, significant hull flow disruption, and susceptibility to fouling and snags. Maintenance was extensive due to exposed components. In rough seas, paddlewheel propulsion is generally less favorable than screw propellers.

Today, paddlewheel propulsion is largely historical and confined to heritage vessels, river steamboats, and certain niche dredging equipment. Most modern ships use screw propellers or water jets, which provide higher efficiency and greater speed in open water. Paddlewheels remain a recognizable symbol of early steam-powered navigation.