PRINCIPLES OF NAVAL ENGINEERING 



INNER BOTTOM PLATING 



TRANSVERSE 



BUTT 



SEAM 



STANCHION 



LONGITUDINAL 

 A" STRAKE 



3.92 



Figure 2-18.— Section of ship, showing plating and framing. 



very great extent. However, riveted joints are 

 still used for some applications. 



Bilge Keels 



Bilge keels, which may be seen in figures 

 2-11, 2-13, and 2-14, are fitted in practically 

 all ships at the turn of the bilge. The bilge keels 

 extend fifty to seventy-five percent of the length 

 of the hull. A bilge keel usually consists of a 

 plate about 12 inches deep, standing at right 

 angles to the shellplating and secured to the 

 shellplating by double angles. On more recent 

 ships, bilge keels consist of two plates forming 

 a Vee shape welded to the hull and on large 

 ships may extend out from the hull nearly three 

 feet. Bilge keels serve to reduce the extent of 

 the ship's rolling. 



Decks 



Decks provide both longitudinal and trans- 

 verse strength to the ship. Deck plates, which 



are similar to the plates used in side and bottom 

 shellplating, are supported by deck beams and 

 deck longitudinals. 



The term strength deck is generally applied 

 to the deck which acts as the top flange of the 

 hull girder. It is the highest continuous deck- 

 usually the main or weather deck. However, the 

 term strength deck may be applied to any con- 

 tinuous deck which carries some of the longi- 

 tudinal load. On destroyers and similar ships 

 in which the main deck is the only continuous 

 high deck, the main deck is the strength deck. 

 The flight deck is the strength deck on recent 

 large aircraft carriers (CVAs) and helicopter 

 support ships (LPH), but the main or hangar 

 deck is the strength deck on older types of car- 

 riers. 



The main deck is supported by deck beams 

 and deck longitudinals. Deck beams are the 

 transverse members of the framing structure. 

 The beams are attached to and supported by the 

 frames at the sides, as shown in figure 2-19. 



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