A bulkhead is an upright wall within the hull of a ship. Other kinds of partition elements within a ship are decks and deckheads.
The word bulki meant "cargo" in Old Norse. The Song Dynasty Chinese author Zhu Yu wrote of Chinese ships with watertight bulkhead compartments in his book Pingzhou Table Talks of 1119 AD. A Chinese trade ship dated to 1277 AD was found off the southern coast of China in 1973, and had 12 bulkhead compartment rooms in its hull.
Sometime in 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.
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 achieve compartmentalisation, a passive fire protection measure.
Requirements of bulkheads
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.
Prevention of damage from EMI and EMP
Bulkheads and decks of warships may be fully grounded
(electrically) as a countermeasure
against damage from EMI
due to nuclear or electromagnetic bomb
detonations near the ship, which could severely damage the vital electronic systems
on a ship.
In the case of firestops, cable jacketing is usually 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.
Other uses of the term
The term was later applied to other vehicles, such as railroad cars
, hopper cars trams
, as well as to containers
, intermediate bulk containers
and fuel tanks
. In some of these cases bulkheads are airtight to prevent air leakage or the spread of a fire. The term may also be used for the "end walls" of bulkhead flatcars
Mechanically, a partition or panel through which connectors pass, or a connector designed to pass through a partition.