Bulkhead (partition)
Vertical partition used in ships, aircraft, and vehicles.
A bulkhead is a vertical partition found inside a ship’s hull, an airplane’s fuselage, or a car’s body. (Other internal dividers on a ship include decks and deckheads.) These walls serve multiple functions: they stiffen the vessel’s structure, separate different areas into rooms, and form watertight compartments that can hold back water if the hull is breached.
The term traces back to Old Norse, where *bulki* meant “cargo.” In 15th-century Europe, shipbuilders realized that internal walls could stop cargo from shifting during a voyage. Since any vertical panel on a ship was called a “head,” walls placed side-to-side across the hull became known as “bulkheads.” Today, the word refers to every vertical panel aboard a ship except the hull itself.
Ancient Greeks used bulkheads in triremes to brace the back of rams. By around 500 BC, Athenian triremes had a reinforced bow compartment behind the ram. Rather than relying on bulkheads for protection against ramming, the Greeks added extra timber along the waterline, making larger ships harder for smaller ones to damage. A twin-hulled boat discovered in Bac Ninh, Vietnam—dated to about 1,600–1,800 years ago—has a series of bulkheads in each hull, making it the oldest known archaeological evidence of such partitions.
Bulkheads are also a noted feature of Chinese junks. In 1119, Song dynasty author Zhu Yu wrote that Chinese ships had bulkhead construction. A 5th-century text, *Garden of Strange Things* by Liu Jingshu, mentioned a ship that could take on water in its bottom without sinking. In 1973, a 24-meter Song dynasty ship dredged off southern China—dated to about 1277—was found with twelve watertight compartments. Travelers like Marco Polo, Ibn Battuta, Niccolò Da Conti, and Benjamin Franklin all described East Asian bulkhead designs. An early 15th-century account notes that Indian ships were built in compartments so that damage to one part left the rest intact—a precursor to modern watertight compartments.
As European shipbuilders replaced wood with iron in the 18th century, bulkheads became more common. They spread widely in Western shipbuilding by the early 19th century. In a 1787 letter, Benjamin Franklin suggested that ships’ holds could be divided into separate, caulked apartments “after the Chinese manner.” A 19th-century shipbuilding book credits Charles Wye Williams with introducing watertight bulkhea
- field
- Shipbuilding, aviation, automotive engineering
- known_for
- Vertical partitions that strengthen structures and create compartments
- earliest_known_use
- Ancient Greek triremes (circa 500 BC)
- earliest_archaeological_evidence
- Bac Ninh, Vietnam (1,600–1,800 years ago)
- notable_early_documentation
- Chinese Song dynasty (1119 book by Zhu Yu)
Lore & Background
Bulkheads were known to the ancient Greeks, who employed them 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. A twin-hulled boat unearthed in Bac Ninh, Vietnam, features a series of bulkheads along each hull, dated to about 1,600–1,800 years ago, representing 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. Song dynasty author Zhu Yu 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 long Song dynasty ship dredged from waters off the southern coast of China in 1973, divided into twelve walled compartmental sections built watertight, dated to about 1277. Texts by Marco Polo, Ibn Battuta, Niccolò Da Conti, and Benjamin Franklin 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.
Reader's Guide
Bulkheads have been a fundamental structural element in shipbuilding for over two millennia, serving to strengthen hulls, divide spaces, and provide watertight compartments. Their use in East Asian shipbuilding, particularly in Chinese junks, was noted by European travelers and later influenced Western maritime design. As wood began to be replaced by iron in European ships in the 18th century, bulkheads became more prevalent, and by the early 19th century they were widespread in Western shipbuilding. Benjamin Franklin wrote in a 1787 letter advocating for dividing holds into separate apartments after the Chinese manner, caulked tight to keep out water. A 19th-century book on shipbuilding attributes the introduction of watertight bulkheads to Charles Wye Williams. In modern ships, not all bulkheads are watertight; the bottom floor is supported against the hull by transverse and longitudinal walls, often with lightening holes. Bulkheads also serve fire-resistance purposes, with classifications per SOLAS. Beyond ships, the term applies to aircraft, automobiles, railroad cars, and other vehicles, where they separate compartments and provide structural integrity.
Did You Know?
- The word 'bulkhead' derives from Old Norse 'bulki' (cargo) and the shipbuilding term 'head' for any vertical panel.
- The earliest archaeological evidence of bulkheads comes from a twin-hulled boat unearthed in Bac Ninh, Vietnam, dated to about 1,600–1,800 years ago.
- A Song dynasty ship dredged off southern China in 1973, dated to about 1277, had twelve watertight bulkhead compartments.
- Benjamin Franklin wrote in a 1787 letter advocating for watertight compartments in ships after the Chinese manner.
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