User:ThoughtIdRetired/draft article on Composite Construction (ship, 19th Century)

The technique of composite ship construction (wooden planking over a wrought iron frame) emerged in the mid-19th century as the final stage in the evolution of fast commercial sailing ships.

Construction of wrought iron hulled vessels had begun in the 1820s and was a mature technology by the time of the launch of the SS Great Britain in 1843. However iron hulls could not be sheathed with copper alloy (due to bimetallic corrosion) and so would become festooned with drag-inducing weed during long voyages in the tropics.

The wooden planking of a composite ship allowed the copper sheathing essential for fast ocean crossings under sail while the iron frame made the ship relatively immune from hogging and sagging, was lighter than the equivalent timber structure and took up less interior space than wooden framing.

The brief reign of composite clippers as the fastest mode of transport between Europe and Asia was brought to a close by the opening of the Suez Canal in 1869 and ongoing improvement in the performance of steamships.

Today only four ships of this type survive, in various states of preservation or decay.


 * City of Adelaide (1864), Passenger Clipper, Transported to Port Adelaide, South Australia, in February 2014; currently on barge, awaiting selection of final shore-based location


 * Cutty Sark (1869), Tea Clipper, Restored, Greenwich, England


 * Ambassador (1869), Tea Clipper, Beached skeleton, Estancia San Gregorio, Chile


 * HMS Gannet (1878), Naval Sloop, Restored, Chatham, England

History
The first patent for a method of composite construction was given to William Watson in 1839. This employed T-bar frames with the planking attached by rivets or bolts. A few ships were built under this and other patents during the 1840s. In 1849 John Jordan, of Liverpool shipbuilder Jordan & Getty, developed a more extensive framing system. An iron plate was fastened along the full length of the keel and up the stem and sternpost. Iron frames were bolted to the plate and stringers were bolted along the outside of the frames. Their first ship built with this method was Excelsior (1850). The next build, Marion MacIntyre (1851) traded to China in 1853 and 1857. Other ships followed from Jordan's yard, using the same technique - also some from builders in Nantes and Bordeaux. Despite this, there was no widespread adoption of the whole system. However, iron knees and deck beams did become common, giving welcome strength and space-saving. Thomas Bilbe patented a compound frame in 1856. Pairs of iron angles were bolted to a wooden filler. The hull planking was attached with bolts that passed through the filler without touching any of the iron. This allowed copper based bolts to be used, so reducing the risk of galvanic action between the fastenings and the hull sheathing. Alexander Stephen