Vice-Admiral Fredrik Henrik af Chapman (9 September 1721 – 19 August 1808) was a Swedish Navy officer, shipwright and scientist. Serving as the manager of the Karlskrona shipyard from 1782 to 1793, Chapman has been credited as the first person to apply scientific methods to shipbuilding and is considered to be the first naval architect.
Chapman was the author of Architectura Navalis Mercatoria (1768) and several other shipbuilding-related works. His Tractat om Skepps-Byggeriet ("Treatise on Shipbuilding") published in 1775 is a pioneering work in modern naval architecture. He was the first shipbuilder in Northern Europe to introduce prefabrication in shipyards and managed to produce several series of ships in record time. He was ennobled as "af Chapman" in 1772, after the successful coup of Gustav III of Sweden.
Fredrik Henrik Chapman was born at Nya Varvet, the royal dockyards in Gothenburg, on 9 September 1721. He was the son of Thomas Chapman, a Yorkshireman born in 1679 who moved to Sweden in 1715 and joined the Swedish Navy in 1716. His mother was Susanna Colson, the daughter of the London shipwright William Colson. Chapman showed a talent for shipbuilding when he made his first body plan based on a drawing of an Ostend privateer given to him by a Flemish shipwright. Chapman went to sea in 1736, at the age of 15, and spent his late teens working in both private and state shipyards. In 1741, he helped build a Spanish merchantmen, a project that provided him with enough money to allow him to work as a ship's carpenter in London until 1744. Following his time in England, he returned to Gothenburg and established a shipyard with a Swedish merchant named Bagge. Together they built a few small vessels and provided maintenance work for the Swedish East India Company.
Though he had received a good basic education in shipbuilding, Chapman recognized that he did not possess the knowledge of higher mathematics that was required to determine draft and stability at the design stage of a vessel. In 1748, he sold his share of the shipyard and moved to Stockholm where he studied for two years under Baron Fredrik Palmqvist. He went on to study under the English professor of mathematics, Thomas Simpson, who had worked out methods for calculating the volume of irregular surfaces and bodies. After one year of studies in London, he went on to study shipbuilding at the British royal dockyards in Woolwich, Chatham and Deptford.
Chapman recorded his extensive research of British shipbuilding in several documents, including an eight-page handwritten document titled Directions for Building of a Ship of 50 Guns, where he described construction methods as well as the British method of launching ships. His activities attracted the interests of British authorities and upon leaving Deptfort in 1753, he was arrested. His papers were confiscated and he was charged with trying to lure shipyards workers into French service. Anglo-French relations were tense, and both Sweden and Denmark were active in uncovering British manufacturing methods as well as trying to persuade British shipwrights to enter their service. Chapman was kept under house arrest for about one month at the cost of half a guinea per day, though he was allowed to visit London with an escort. All of his documents were eventually returned to him except a rigging plan. After his release, he stayed a few months to study experimental physics and took lessons in engraving.
In 1754, Chapman continued his educational tour by going to the Netherlands and in 1755 to France, where he was given permission to stay at the royal shipyards at Brest to observe warship construction. There he observed the complete process of construction of the French 60-gun ship Célèbre from keel-laying to rigging under the French shipwright Geoffrey the Elder. He also made line drawings and plans of several French ships, including the huge Ville de Paris and the 64-gun Bienfaisant and pen and ink drawings of ship decorations. The experience in Brest is believed to have made a deep impression on Chapman, later contributing to his conviction that 60-gun ships were the most appropriate for Swedish service.
French authorities were the first to recognize Chapman's skills and attempted to convince him to stay and enter service for France, an offer he declined. After Chapman returned to London in 1756, First Lord of the Admiralty Lord Temple tried to do the same, and came close to succeeding by using patriotic appeals to Chapman's English heritage. In his memoirs, Chapman wrote that he would likely have stayed had Temple not been replaced as First Lord of the Admiralty by Lord Winchilsea soon after their meeting. Instead, he was recruited by the Swedish minister in Paris, Ulrik Scheffer, later Minister of External Affairs under Gustav III.
In 1757, Chapman was made assistant shipwright at the royal dockyards in Karlskrona at the age of 36. Soon after his appointment, he drafted his ideal plans for docks, which included facilities for properly ventilated sail storage and advanced dock pumps that could be powered by human power, horses or wind mills. The plans would, however, not be realized until much later, when Chapman was made chief shipwright of the Karlskrona yards.
In November 1758 to April 1759, he was charged with a timber inspection cruise along the coasts from Turku up to the Gulf of Bothnia. Later, Chapman moved first to Stralsund (then a Swedish possession) where he stayed until 1762, and later to Sveaborg where he stayed until 1764. His first major assignment came in 1760. The recently formed archipelago fleet (skärgårdsflottan), an inshore fleet independent of the navy under the command of the army, was in need of new vessels to replace the galleys which had proved problematic in the war against Prussia that had broken out in 1757. Augustin Ehrensvärd, the commander of the archipelago fleet and the man in charge of the construction of the new naval base and fortress of Sveaborg, began a successful collaboration with Chapman in designing new types of what would later be called "archipelago frigates" (skärgårdsfregatter). Inspired by Russian "chebecks" (variants of Mediterranean xebecs, hybrid sailing ships that incorporated features of galleys), the two created craft that could be rowed, but with heavier armament and additional protection for the crew, a necessity in the cold Baltic climate. The cooperation resulted in four new types of archipelago frigates: udema, pojama, turuma and hemmema, all named after the Finnish names of Swedish provinces in Finland, the coasts of which they were intended to protect.
By closely examining drawings of ships with known good sailing qualities Chapman realized that the framework should be divided in a certain progression. The frames should decrease from the place of greatest width in the same relation as the ordinates 0, 1, 2, 3, 4 etc. (pictured), where the arc ABC is a parabola, AD is the axis and A is the vertex (the "peak"). This construction method is called the "parabola method". Chapman also introduced the so called "relaxation method", but preferred the former himself.
At Sveaborg, Chapman supervised and led the construction and expansion of the naval yards, including cranes, docks and various buildings. He moved to Stockholm in 1764, but remained in charge of the design of vessels for the archipelago fleet. He was also made a part of a commission that was to propose improvements on the expansion of the high seas navy. Its final report was presented in 1764 and recommended new designs for standardized ships of the line ranging from 50 to 70 guns. The report represented the ideals of a new school of shipwrights that favored scientific methods and the use of theoretical models at all stages in ship design, a view that was in conflict with the old school, which favored slow evolution based on practical experimentation. The old school, represented most prominently by Gilbert Sheldon, came into conflict with the new ideas, but lost the debate when the Board of the Admiralty favored the findings of the commission at the Riksdag in March 1769 and put Chapman in charge of designing the navy's new warships.