Principles of naval engineering - Historic Naval Ships Association

PRINCIPLES OF NAVAL ENGINEERINGMAIN DECKSTRINGERLONGITUDINALSVCL11.30(147)AFigure 2-8.— Angle, I-beam, tee, bulbangle, and channel frames.WELO' (SHELL ORBULKHEAD)REVERSE BARFRAME BAR11,30(147)BFigure 2-9.— Built-up frames.SOLID WEB147.14Figure 2-10.—Web frame used in wingtank construction.Both intercostal and continuous frames areshown in figure 2-12.A cellular form of framing results from acombination of longitudinal and transverseframing systems utilizing closely spaced deepframing. Cellular framing is used on mostnaval ships.BILGEKEELLONGITUDINALSKEEL147.15Figure 2-11.— Basic frame section(longitudinal framing).In the bottom framing, which is probablythe strongest part of a ship's structure, thefloors and keelsons are integrated into a rigidcellular construction (fig. 2-13). Heavy loadssuch as the ship's propulsion machinery arebolted to foundations which are built directlyon top of the bottom framing (fig. 2-14).Double BottomIn many naval ships, the inner bottom platingis a watertight covering laid on top of thebottom framing. The shellplating, framing,and inner bottom plating form the space knownas the double bottom . This space may be usedfor stowage of fresh water or fuel oil or itmay be used for ballasting.The inner bottom plating is a second skininside the bottom of the ship. It preventsflooding in the event of damage to the outerbottom, and it also acts as a strength member.Stem and Bow StructureThe stem assembly, which is the forwardmember of the ship's structure, varies in form20