In the 1830s, Francis Pettit Smith and John Ericsson became leading advocates of screw propulsion. Smith's early full-helical screw looked efficient in theory but distributed power poorly in real water, prompting rapid simplification toward a single turn and later blade forms. Ericsson pursued a straight shaft arrangement and contra-rotating propellers in search of efficiency. Their competing schemes show why early designers had to solve shaft transmission, watertightness, and useful thrust together rather than treating the propeller as an isolated component.
Chapter · 1:40-5:16
Smith and Ericsson turn screw propulsion into a practical system
The first practical screw-propulsion schemes expose the engineering problems hidden beneath a ship's waterline, from shaft sealing to useful thrust.