Joseph Ludwig Franz Ressel (Czech: Josef Ludvík František Ressel; 29 June 1793 - 9 October 1857) was a Czech-Austrian forester and inventor who designed one of the first working ship's propellers.
Ressel was born in Chrudim, Bohemia, Austrian Empire. His father was a German native speaker, while his mother's mothertongue was Czech. He studied in the Linz Gymnasium, České Budějovice artillery school, Vienna university and at the Mariabrunn Forestry Academy in Mariabrunn.
He worked for the Austrian government as a forester in the more southern parts of the monarchy, including in Motovun, Istria (modern-day Croatia). His work was to secure a supply of quality wood for the Navy. He worked in Landstrass (Kostanjevica on the Krka river in Carniola in modern-day Slovenia), where he tested his ship propellers for the first time. In 1821 he was transferred to Trieste (modern-day Italy), the biggest port of the Austrian Empire, where his tests were successful. He was awarded a propeller patent in 1827. He modified a steam-powered boat Civetta by 1829 and test-drove it in the Trieste harbor at six knots before the steam conduits exploded. Because of this misfortune, the police banned further testing. The explosion was not caused by the tested propeller as many believed at the time.
As early as 1804, the American John Fitch is credited with a screw propeller, which was unsuccessful. In 1836, the Englishman Francis Pettit Smith tested a screw propeller similar to Ressel's. The first transatlantic journey of a ship powered by a screw-propeller was by the SS Great Britain in 1845. Propeller design stabilized in the 1880s.
Besides having been called "the inventor of the propeller", he was also called the inventor of the steamship and a monument to him in a park in Vienna commemorates him as “the one and only inventor of the screw propeller and steam shipping”.
Among other Ressel's inventions are pneumatic post and ball and cylinder bearings. He was granted numerous patents during his life.
He died in Ljubljana, and was buried in the St. Christopher Cemetery in the Bežigrad district.