Bulkhead (partition)

A bulkhead is an upright wall within the hull of a ship, the fuselage of an airplane, or the body of a car. Other kinds of partition elements within a ship are decks and deckheads.

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".^{[dubious – discuss]} Now, the term bulkhead applies to every vertical panel aboard a ship, except for the hull itself.

Bulkheads were known to the ancient Greeks, who employed bulkheads in triremes to support the back of rams. By the Athenian trireme era (500 BC), the hull was strengthened by enclosing the bow behind the ram, forming a bulkhead compartment. Instead of using bulkheads to protect ships against rams, Greeks preferred to reinforce the hull with extra timber along the waterline, making larger ships resistant to ramming by smaller ones.

A twin-hulled boat unearthed in Bac Ninh, Vietnam, features a series of bulkheads along each hull, which help strengthen the structure. The boat is dated to about 1,600–1,800 years ago. If so, this would represent the earliest archaeological evidence of bulkheads found anywhere in the world to date.

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.

As wood began to be replaced by iron in European ships in the 18th century, new structures, like bulkheads, started to become prevalent. 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.

Bulkheads in a ship serve several purposes: