TABLE OF CONTENTS This chapter deals with the internal vertical structure of the ship. Much of this structure, particularly the pillars and to some extent the transverse strength bulkheads, is responsible for carrying the vertical loading experienced by the ship. The principal bulkheads subdivide the ship hull into a number of large watertight compartments, and their construction and spacing is discussed. Also considered are the boundaries of other smaller compartments such as deep tanks and the shaft tunnel.
Vertical partitions in a ship arranged transversely or fore and aft are referred to as 'bulkheads'. Those bulkheads which are of greatest importance are the main hull transverse and longitudinal bulkheads dividing the ship into a number of watertight compartments. Other lighter bulkheads, named 'minor bulkheads', which act as screens further subdividing compartments into small units of accommodation or stores, are of little structural importance.
The main hull bulkheads of sufficient strength are made watertight in order that they may contain any flooding in the event of a compartment on one side of the bulkhead being bilged. Further they serve as a hull strength member not only carrying some of the ship's vertical loading but also resisting any tendency for transverse deformation of the ship. As a rule the strength of the transverse watertight bulkheads is maintained to the strength deck which may be above the freeboard deck. Finally each of the main hull bulkheads has often proved a very effective barrier to the spread of a hold or machinery space fire.
