PRINCIPLES OF NAVAL ENGINEERING 



Bulkheads consist of plating and reinforcing 

 beams. The reinforcing beams are known as 

 bulkhead stiffeners . Two types of bulkhead stif- 

 feners are shown in figure 2-21, Bulkhead 

 stiffeners are usually placed in the vertical 

 plane and aligned with deck longitudinals; the 

 stiffeners are secured at top and bottom to any 

 intermediate deck by brackets attached to deck 

 plating. The size of the stiffeners depends 

 upon their spacing, the height of the bulkhead, 

 and the hydrostatic pressure which the bulkhead 

 is designed to withstand. 



Bulkheads and bulkhead stiffeners must be 

 strong enough to resist excessive bending or 

 bulging in case of flooding in the compartments 

 which they bound. If too much deflection takes 

 place, some of the seams might fail. 



In order to form watertight boundaries, 

 structural bulkheads must be joined to all 

 decks, shellplating, bulkheads, and other struc- 

 tural members with which they come in contact. 

 Main transverse bulkheads extend continuously 

 through the watertight volume of the ship, from 

 the keel to the main deck, and serve as flooding 

 boundaries in the event of damage below the 

 waterline. 



In general, naval ships are divided into as 

 many watertight compartments, both above and 

 below the waterline, as are compatible with the 

 missions and functions of the ships. The com- 

 partmentation provided by transverse and longi- 

 tudinal bulkheads is illustrated in the bow sec- 

 tion shown in figure 2-22. 



SHIP COMPARTMENTATION 



Every space in a naval ship (except for 

 minor spaces such as peacoat lockers, linen 

 lockers, cleaning gear lockers, etc.) is consid- 

 ered as a compartment and is assigned an iden- 

 tifying letter-number symbol. This symbol is 

 marked on a label plate secured to the door, 

 hatch, or bulkhead of the compartment. 



There are two systems of numbering com- 

 partments, one for ships built prior to March 

 1949 and the other for ships built after March 

 1949. In both of these systems, compartments 

 on the port side end in an even number and those 

 on the starboard side end in an odd number. In 

 both systems, a zero precedes the deck number 

 for all levels above the main deck. 



Figure 2-23 illustrates both systems of 

 numbering decks. The older system identifies 

 decks by the numbers 100, 200, 300, etc., with 

 the number 900 always being used for the double 



T-BAR' 



ANGLE' 



11.30(147)C 

 Figure 2-21.— Bulkhead stiffeners. 



147.24 

 Figure 2-22.— Compartmentation provided by 

 transverse and longitudinal bulkheads. 



bottoms. In the newer system, decks are iden- 

 tified as 1, 2, 3, 4, etc., and the double bottoms 

 are given whatever number falls to them. 



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