Chapter 2-SHIP DESIGN AND CONSTRUCTION 



An example of a compartment symbol on a 

 ship built prior to March 1949 is given in figure 

 2-25. 



SHIPS BUILT AFTER MARCH 1949 



For ships constructed after March 1949, the 

 compartment numbers consist of a deck num- 

 ber, frame number, relation to centerline of 

 ship, and letter showing use of the compartment. 

 These are separated by dashes. The A, B, C 

 divisional system is not used. 



The main deck is always numbered 1. The 

 first deck or horizontal division below the main 

 deck is numbered 2; the second below is num- 

 bered 3; etc., consecutively for subsequent 

 lower division boundaries. Where a compart- 

 ment extends down to the bottom of the ship, 

 the number assigned the bottom compartments 

 is used. The first horizontal division above the 

 main deck is numbered 01, the second above is 

 numbered 02, etc., consecutively, for subsequent 

 upper divisions. The deck number becomes the 

 first part of the compartment number and indi- 

 cates the vertical position within the ship. 



The frame number at the foremost bulkhead 

 of the enclosing boundaryof a compartment is its 

 frame location number. Where these forward 

 boundaries are between frames, the frame num- 

 ber forward is used. Fractional numbers are not 

 used. The frame number becomes the second 

 part of the compartment number. 



Compartments located so that the centerline 

 of the ship passes through them carry the num- 

 ber 0. Compartments located completely to 

 starboard of the centerline are given odd num- 

 bers and those completely to port of the center- 

 line are given even numbers. Where two or 

 more compartments have the same deck and 

 frame number and are entirely to port or en- 

 tirely to starboard of the centerline, they have 

 consecutively higher odd or even numbers, as 

 the case may be, numbering from the centerline 

 outboard. In this case, the first compartment 

 outboard of the centerline to starboard is 1; the 

 second is 3, etc. Similarly, the first compart- 

 ment outboard of the centerline to port is 2; 

 the second 4, etc. When the centerline of the 

 ship passes through more than one compart- 

 ment, the compartment having that portion of 

 the forward bulkhead through which the center- 

 line of the ship passes carries the number 0, 

 and the. others carry the numbers 01, 02, 03, 

 etc., in any sequence found desirable. These 

 numbers indicate the relation to the centerline. 



and are the third part of the compartment 

 number. 



The fourth and last part of the compartment 

 number is the capital letter which identifies 

 the assigned primary usage of the compart- 

 ment. A single capital letter is used, except that 

 on dry and liquid cargo ships a double letter 

 designation is used to identify compartments 

 assigned to cargo carrying. The compartment 

 letters for ships built after March 1949 are 

 shown in figure 2-26. An example of a com- 

 partment symbol on a ship built after March 

 1949 is given in figure 2-27, 



3-.75..4-M 



L 



Ammunition compartment 



Second compartment outboard of 

 the centerline to port 



.Forward boundary is on or im- 

 mediately aft of frame 75 



.Third deck 



147.27 

 Figure 2-27.— Example of compartment symbol 

 on ship built after March 1949. 



GEOMETRY OF THE SHIP 



Since a ship's hull is a three-dimensional 

 object having length, breadth, and depth, and 

 since the hull has curved surfaces in each 



23.191 

 Figure 2-28.— Transverse, horizontal, and ver- 

 tical planes. 



29 



