PRINCIPLES OF NAVAL ENGINEERING 



TAN e = TANGENT OF ANGLE OF LIST = -5-. 



147.32 

 Figure 3-16.— Measuring the angle of list pro- 

 duced in performing the inclining experiment. 



EFFECTS OF WEIGHT SHIFTS 



If one weight inasystemof weights is moved, 

 the center of gravity of the whole system moves 

 along a path parallel to the path of the compo- 

 nent weight. The distance that the center of grav- 

 ity of the system moves may be calculated from 

 the formula. 



pp _ ws^ 

 ^°1- w 



where 



w = component weight, in tons 



s = distance component weight is moved, in 

 feet 



W = weight of entire system, in tons 



GG^ = shift in center of gravity of system, in 

 feet 



Weight movements in a ship can take place 

 in three possible directions— athwartships, fore 

 and aft, and vertically (perpendicular to the 

 decks). The most general type of movement is 

 inclined with respect to all three of these. Such 



a diagonal movement can be divided into com- 

 ponents in each of the three directions, and one 

 component can be studied at a time without ref- 

 erence to the others. For example, if a weight 

 is moved from the main deck, starboard side, 

 aft, to a storeroom on the 4th deck, port side, 

 forward, this movement may be regarded as 

 taking place in three steps, as follows: 



1. from main deck to 4th deck (down) 



2. from starboard side to port side (across) 



3. from stern to bow (forward) 



VERTICAL WEIGHT SHIFT 



If a weight is moved straight up a vertical 

 distance on a ship, the ship's center of gravity 

 will move straight up on the centerline (fig. 

 3-17). The vertical rise in G (explained later 

 in the chapter) can be computed from the for- 

 mula mentioned previously. 



Example : A ship is operating with a dis- 

 placement of 11,500 tons. Her ammunition, 

 totaling 670 tons, is to be moved from the 

 magazines to the main deck, a distance of 36 

 feet. Find the rise in G. 



„„ 670 x 36 

 ^n 11,500 



2.1 feet 



w RELOCATED ^ 

 TO HERE I 



Figure 3-17. -Shift 



147.33 

 in G due to vertical weight 

 shift. 



44 



