Bulkhead (partition)
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A bulkhead is an upright wall within the hull of a ship. Bulkheads in a ship serve several purposes: They 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. When equipped with purpose-designed fireproofing, bulkheads and decks are able to achieve fire-resistance ratings in an effort to achieve compartmentalisation, which is a passive fire protection measure, subject to stringent bounding. Openings in fire-resistance rated bulkheads and decks must be firestopped to restore the fire-resistance ratings that would otherwise be compromised, if the openings were left unsealed. The Authority Having Jurisdiction for such measures varies depending upon the flag of the ship. Merchant vessels are typically subject to the regulations and inspections of the Coast Guards of the flag country. Combat ships are subject to the regulations set out by the navy of the country that owns the ship. Combat ships may also be equipped to have its bulkheads and decks fully grounded (electrically), as a countermeasure against EMI and EMP damage, resulting from nuclear blasts and/or the breaking of the sound barrier near a vessel, which could otherwise severely damage the electronic systems on a ship, thus negating its combat power. In the case of firestops, cable jacketing is typically removed within the seal and firestop rubber modules are internally fitted with copper shields, which contact the cables' armour in order to ground the seal. There are also conductive fill materials in use for that purpose, which must be in direct contact with cable armour to ensure full grounding of the bulkheads and decks. Any openings that are not fully grounded would defeat that purpose.
The word bulki meant "cargo" in Old Norse. Sometime in the 15th century sailors and builders 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, by extension, the term applies to every vertical panel aboard a ship, except for the hull itself.
The term was later applied to other vehicles, such as trams, aircraft or spacecraft, as well as to containers, such as fuel tanks. In some of these cases bulkheads are airtight to prevent air leakage or the spread of a fire.
Other kinds of partition elements within a ship are decks and deckheads.
