Smith, Sir Francis Pettit

Smith, Sir Francis Pettit (1808–74), British inventor. He started life as a Kentish farmer, but became engrossed in the construction of model boats and in methods of propelling them. In 1835 he constructed one which was driven by a propeller actuated by a spring. This was so successful that he became convinced of its superiority over the paddle wheel which was universally used at that time with steam propulsion.

Smith was unaware that three others, including the Swedish engineer John Ericsson (1803–89), were separately working to develop a propeller, and, in fact, his patent for his type of screw propulsion, taken out on 31 May 1836, pre-dated Ericsson's different type by only six weeks. Thus Smith's improved model exhibited in that year can claim to have been the first of its kind, though Ericsson was awarded part of the £20,000 offered by the British Admiralty for the successful development of this method of propulsion.

With financial backing and some technical assistance, Smith now built a 10-ton vessel propelled by a 6-horsepower engine which successfully drove a wooden screw. To satisfy Admiralty demands for experiments in a larger ship, a company was formed to build the 237-ton propeller-driven Archimedes, which in October 1839 achieved a speed of 10 knots and later made a successful cruise to the major ports of Britain, to Amsterdam, and to Oporto. This convinced the Admiralty to build its first screw-driven warship, which was launched in 1841, but Smith received only a meagre financial reward for his invention. He was also poorly paid as adviser to the Admiralty, a post he held until 1850. However, in recognition of his services he was knighted in 1871.