Sir John Isaac Thornycroft (1 February 1843 – 28 June 1928) was an English shipbuilder, the founder of the Thornycroft shipbuilding company and member of the Thornycroft family. Early life He was born in 1843 to Mary Francis and Thomas Thornycroft. He attended the Regent Street Polytechnic and then the Royal School of Naval Architecture and Marine Engineering at South Kensington and at the same time, he began building the steam launch Nautilus in his father's study. Nautilus was a fast boat with a reliable engine (also built by Thornycroft), and in 1862 it proved to be the first steam launch with enough speed to follow the contenders in the University race. The ensuing publicity prompted his father to purchase a strip of land along the Thames, adjacent to Chesterman's yard at Chiswick in 1864, and that became the start of John Thornycroft's shipbuilding career. In 1866 Thornycroft took over Chesterman's yard completely, and John I. Thornycroft & Company was formally established, but at the beginning, John Thornycroft did not work there full-time. Instead he worked for a while at Palmers Shipbuilding and Iron Company in Jarrow-on-Tyne before studying for a diploma in engineering at the University of Glasgow. At Glasgow he studied under Lord Kelvin and Professor Macquorn Rankine. In 1870, Thornycroft married Blanche Ada Coules (1846–1936) and they had two sons and five daughters. Three of their children, John Edward Thornycroft, Blanche Thornycroft and Isaac Thomas (known as Tom) Thornycroft would go on to be involved in the family business. Edith Alice; Mary Beatrix; Ada Francis; and Eldred Elizabeth do not seem to have been involved. On his return from Scotland Thornycroft built the fast steam yacht Miranda in 1871, and thereby proved that small vessels could obtain speeds that were not thought possible at the time. Engineering career The exploits of Miranda gave rise to further orders of similar vessels, including Gitana, built in 1876 and capable of , which was an astonishing speed at the time. Besides the yacht sales, Thornycroft found an even more lucrative business building torpedo boats. It started with for Norway in 1873, a light vessel built of thin steel plates. The early torpedo boats were designed for spar torpedoes, but when a new generation of self-propelled torpedoes arrived from Whitehead in 1876, the torpedo boat really found its form. Thornycroft designed HMS Lightning for the Royal Navy, on the lines of