A bulkhead is an upright wall within the hull of a ship or within the fuselage of an airplane. Other kinds of partition elements within a ship are decks and deckheads. Etymology The word bulki meant "cargo" in Old Norse. During the 15th century sailors and builders in Europe realized that walls within a vessel would prevent cargo from shifting during passage. In shipbuilding, any vertical panel was called a head. So walls installed abeam (side-to-side) in a vessel's hull were called "bulkheads". Now, the term bulkhead applies to every vertical panel aboard a ship, except for the hull itself. History Bulkhead partitions are considered to have been a feature of Chinese junks, a type of ship. Song Dynasty author Zhu Yu (fl. 12th century) wrote in his book of 1119 that the hulls of Chinese ships had a bulkhead build. The 5th-century book Garden of Strange Things by Liu Jingshu mentioned that a ship could allow water to enter the bottom without sinking. Archaeological evidence of bulkhead partitions has been found on a 24 m (78 ft) long Song Dynasty ship dredged from the waters off the southern coast of China in 1973, the hull of the ship divided into twelve walled compartmental sections built watertight, dated to about 1277. Texts written by writers such as Marco Polo (1254–1324), Ibn Battuta (1304–1369), Niccolò Da Conti (1395–1469), and Benjamin Franklin (1706–1790) describe the bulkhead partitions of East Asian shipbuilding. An account of the early fifteenth century describes Indian ships as being built in compartments so that even if one part was damaged, the rest remained intact — a forerunner of the modern day watertight compartments using bulkheads. Bulkhead partitions became widespread in Western shipbuilding during the early 19th century. Benjamin Franklin wrote in a 1787 letter that "as these vessels are not to be laden with goods, their holds may without inconvenience be divided into separate apartments, after the Chinese manner, and each of these apartments caulked tight so as to keep out water." A 19th century book on shipbuilding attributes the introduction of watertight bulkheads to Charles Wye Williams, known for his steamships. Purpose Bulkheads in a ship serve several purposes: increase the structural rigidity of the vessel, divide functional areas into rooms and create watertight compartments that can contain water in the case of a hull breach or other leak. some bulkheads and decks are fire-resistance rated to