Chapter 2-SHIP DESIGN AND CONSTRUCTION 



DECK STRINGER 



SHEER STRAKE 

 ("G" STRAKE) 



GARBOARD OR "A" STRAKE 



147.12 



Figure 2-6.— Destroyer hull girder, showing some strength members. 



built-up frames, one of welded construction and 

 the other of riveted construction. 



Frames are strength members. They act 

 as integral parts of the ship girder when the 

 ship is exposed to longitudinal or transverse 

 stresses. Frames stiffen the plating and keep 

 it from bulging or buckling. They act as girders 

 between bulkheads, decks, and double bottoms, 

 and transmit forces exerted by load weights 

 and water pressures. The frames also support 

 the inner and outer shell locally and protect 

 against unusual forces such as those caused 

 by underwater explosions. As may be inferred, 

 frames are called upon to perform a variety 

 of functions, depending upon the location of the 

 frames in the ship. Figure 2-10 shows a web 

 frame used in wing tank construction. 



There are two important systems of fram- 

 ing in current use: the transverse system and 

 the longitudinal system. The transverse system 

 provides for continuous transverse frames with 

 the longitudinals intercostal between them. 

 Transverse frames are closely spaced and 

 a small number of longitudinals are used. The 

 longitudinal system of framing consists of 

 closely spaced longitudinals which are con- 

 tinuous along the length of the ship, with trans- 

 verse frames intercostal between the longitu- 

 dinals. 



Transverse frames are attached to the keel 

 and extend from the keel outward around the 



turn of the bilge and up to the edge of the main 

 deck. They are closely spaced along the length 

 of the ship, and they define the form of the ship. 



Longitudinals (fig. 2-11) run parallel to the 

 keel along the bottom, bilge, and side plating. 

 The longitudinals provide longitudinal strength, 

 stiffen the shellplating, and tie the transverse 

 frames and the bulkheads together. The longi- 

 tudinals in the bottom (called side keelsons ) 

 are of the built-up type. 



Where two sets of frames intersect, one 

 set must be cut to allow for the other set. 

 The frames which are cut, and thereby weakened, 

 are known as intercostal frames ; those which 

 continue through are called continuous frames . 



INNER BOTTOM 



RIDER PLATE 



VERTICAL KEEL 



DISHED OR FLAT KEEL PLATE 



COLLAR PLATE 



SHELL PLATING 



147.13 

 Figure 2-7. — One type of keel structure. 



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