Blue Plaque for Pioneer of the Screw-Propeller

Sir Francis Pettit Smith Blue Plaque at 17 Sydenham Hill SE26 An English Heritage Blue Plaque has been erected at 17 Sydenham Hill SE26, home to Sir Francis Pettit Smith (1808-1874), pioneer of the screw-propeller, where he lived from 1864-1870. Smith’s determination and engineering skill ensured that the screw-propeller overtook the paddle-wheel as the standard method of steam-ship propulsion: in May 1836, he took out a patent for screw propulsion, just weeks before his rival and eventual friend, Captain John Ericcson, who was carrying out similar experiments. Though Smith’s idea was netiher new nor unique, Pieter van der Merwe of the National Maritime Museum, writing in 2002, described the results of Smith’s work as having led to an ‘epoch-making change’.

Smith was born in Kent, the only son of Charles Smith, Post-Master of Hythe, and Sarah Pettit. He attended a private school in Ashford after which he became a grazing farmer on Romney Marsh, before moving on to Gutters Hedge Farm in Middlesex. As a boy, Smith had shown considerable interest and ingenuity in the construction and propulsion of model boats and, even as a farmer, he continued to devote much of his time to the subject. Smith believed that a screw-propeller would be a more efficient form of propulsion than the paddle-wheel, then exclusively used by steamships.

In 1835 he demonstrated a model boat propelled by a wooden screw driven by a spring. Smith was unaware that this method of propulsion had been invented as early as the seventeenth century by Robert Hooke and that there had already been a number of demonstrations of manually turned full-scale propellers. However Smith brought something new to the table, having managed to solve the problem of integrating a steam engine and propeller with a driveshaft that would work effectively, and yet remain watertight where it passed through a ship’s hull.

In late 1836 – in a bid to convince potential customers, notably the British Admiralty, of the merits of his system – Smith built a six-ton launch, the Francis Smith, which was fitted with a thirty-inch two-turn wooden screw and a single cylinder engine. During the vessels trials Smith made a fortunate discovery. Half the screw broke off when its propeller hit an obstacle in the water and, with a shorter propeller, the vessel’s speed actually increased. Fitted with a new, short propeller, the Francis Smith steamed around the Kent coast and its excellent performance in stormy weather attracted the attention of the Admiralty who persuaded Smith to build a larger ship, the Archimedes, which was launched in 1838.

The Archimedes ran a series of trials for the Admiralty, regularly outperforming paddle-ships of a similar size and reaching speeds nearly twice that expected. In 1840 the Admiralty ordered the construction of HMS Rattler, the Navy’s first screw-driven warship. In 1845 Rattler was pitted against Alecto, a paddle-steamer of similar size and the superiority of the screw was demonstrated in a series of races and nautical tugs of war. Within twenty years, 2,300 Navy and merchant ships had been fitted with the screw. One of these was Isambard Kingdom Brunel’s Great Britain, which was originally intended to be fitted with paddles.

Despite its apparent success, Smith and his backers derived little profit from his invention. Smith was retained by the Admiralty as an advisor until 1850, was awarded a civil list pension in 1855, and received a share of a one-off payment by the authorities to all propeller designers, but the Admiralty’s failure to purchase the Archimedes, which had cost £10,500 to build, was a major financial blow. Manufacturers had invested a lot of money in the paddle-driven system and many were extremely reluctant to abandon it. As a result, sales of Smith’s system were initially very low and after his patent expired in 1856 he retired to Guernsey as a farmer.

Even so, such was Smith’s reputation amongst his colleagues that in 1857 he was the recipient of a national testimonial, a service of plate and a purse of nearly £3,000, subscribed to by many in the shipbuilding world. In 1860 Smith returned to England when he was appointed Curator of the Patent Office Museum in South Kensington. He was knighted in 1871 and died in South Kensington three years later. Robert Stephenson observed in his lifetime that ‘Mr Smith worked from a platform which might have been raised by others… but he had made a stride in advance which was almost tantamount to a new invention’.