A bulkhead is a wall inside a craft such as a ship, airplane, or spacecraft. Bulkheads serve a number of structural functions, and there are a wide array of variations on the basic bulkhead design which can be used in specific applications. The term “bulkhead” may also be used to describe a retaining wall in a mine or along a seashore used for control of flood and erosion.
The Chinese appear to have been the first to use bulkheads in their ships. When mariners from other regions encountered Chinese ships, they took note of the bulkhead design and adopted it for themselves, causing it to spread rapidly across many shipbuilding cultures. Prior to the use of bulkheads, the entire hull of a ship would be open, creating a cavernous space.
One of the most obvious reasons to install bulkheads is to divide a space into usable compartments. Using bulkheads inside a ship, for example, breaks the space up, which makes it easier to store cargo and to establish accommodations for people on board the boat. Historically, the use of bulkheads radically changed shipping, because it allowed companies to sequester various products and to organize their loads without needing to worry about shifting weight, since the bulkheads held materials in place.
Bulkheads also contribute to the structural stability and rigidity of a craft. In heavy seas, a ship with bulkheads will usually withstand the conditions better than a ship which lacks these internal walls, and the same holds true for aircraft, which must endure violent shearing forces on a regular basis. Engineers have refined bulkhead designs to provide maximum structural stability while adding minimal amounts of weight to ensure that craft are still capable of moving.
The final and perhaps most important reason to install a bulkhead is for safety. The compartmentalized design created with bulkheads allows people to contain fire, flooding, and other issues so that an entire craft is not ruined when accidents or sabotage occur. Requiring bulkheads for safety reasons is common in many areas of the world, and this concern also dictates the materials used in their construction, and the fittings which may be attached to them.
Incidentally, in situations where people are allowed to pick their seats on an aircraft, bulkhead seats are typically the best choice, because they have more leg room. Emergency exit rows can also be a good choice, as they also have additional legroom, but certain responsibilities are attached to the people who sit in these seats if an emergency evacuation occurs.