A bulkhead is a vertical partition or wall within the hull of a ship, submarine, or boat, crucial for structural strength and safety. They divide the interior into compartments, provide rigidity to the hull, restrict flooding via watertight construction, and prevent the spread of fire.

Key Aspects of Bulkheads:
Watertight Integrity: They are often designed to seal off sections of a vessel, ensuring it remains buoyant even if one part is flooded.

Structural Support: They act as vertical stiffeners that strengthen the hull and help maintain the vessel's overall shape.

Types by Orientation:
Transverse Bulkheads: Run from side-to-side, providing lateral strength and dividing the ship into watertight compartments.

Longitudinal Bulkheads: Run fore and aft, offering longitudinal strength.

Types by Construction:
Plain: Flat plates supported by stiffeners.

Corrugated: Plates with a folded shape to reduce weight and the need for welded stiffeners.

Specialized Types:
Collision Bulkhead: A specially reinforced, watertight bulkhead placed at the front (bow) to prevent flooding in case of a head-on collision.

Tank Bulkhead: Used for partitioning tanks holding oil or water.

Apart from ships, the term is also used in aviation and civil engineering to describe partitioning walls.