DIAGRAMS AND BLUEPRINTS
use most. To better understand the ship's plans and blueprints, you should complete the correspondence course Blueprint Reading and Sketching, NAVEDTRA 10077.
In addition to knowing how to read drawings, you must also know how to locate applicable drawings. The onboard drawings, which are sometimes referred to as ship's plans or ship's blueprints, are listed in the Ship's Drawing Index (SDI). The SDI is kept in the engineering department office (log room).
The SDI lists all working drawings that have a NAVSHIPS or NAVSEA drawing number, all manufacturer's drawings, all equipment drawing lists, and all assembly drawings that list detail drawings. Drawings that are actually kept on-board are identified in the SDI by an asterisk (*).
Drawings are listed in numerical order in the SDI. Two types of numbering systems are in use for drawings that have NAVSHIPS or NAVSEA numbers. The older system (NAVSHIPS) is an Sgroup numbering system. The newer system is used on all NAVSEA drawings since 1 January 1967.
Figure 2-5.-Some symbols used on damage control diagrams.
The onboard drawings are filed in numerical sequence. On most ships, they are kept in file cabinets in the log room. However, they may be filed in a technical library or the microfilm library on aircraft carriers, tenders, and repair ships.
Although you may use blueprints and drawings for damage control purposes, you will primarily use the isometric damage control diagrams (shown in fig. 2-4). These diagrams are three-dimensional. They are developed and provided under strict requirements set forth by NAVSEA. When NAVSEA furnishes a group of ships their diagrams, the ship's force must verify the diagrams for accuracy. Corrections should be made to show the actual installation within the ship. In order to read these diagrams correctly, you need to recognize the standard symbols used. A few of these symbols are shown in figure 2-5. Each diagram will have a key, which will identify the symbols used on that diagram. As a rule, the different systems are drawn in different colors. This makes it easier to distinguish one system from another.
Isometric damage control diagrams that are not kept in the damage control books are usually sealed in plastic. They are stowed in special cabinets like those in figure 2-6. These cabinets
Figure 2-6.-Cabinet for isometric damage control diagrams.
and diagrams are located in DCC and in thevarious repair party lockers.
On the isometric damage control diagrams,each deck or platform is shown at a separate level. Compartments that are not intersected by a particular deck are not shown on the diagram for that deck. Instead, they are drawn as part of the deck from which they extend. Heavy lines indicate watertight and oiltight boundaries. Lighter lines indicate airtight, fumetight, and nontight boundaries.
The isometric damage control diagrams showpiping systems as close as possible to their actual shipboard locations. All piping and fittings that are actually contained within a compartment are shown in that compartment on the diagram. However, the precise location may be shifted a little in order to make the diagram clear and readable. Dotted lines and cross-hatchings indicate hidden boundaries, piping, and valves. Usually the isometric damage control diagrams are not drawn to scale. Plan views of the firemain system, the main steam system, and the main drain system are usually maintained on pegboards in DCC. The valves in these plan views are indicated by pegs that can be turned to show whether the valve is open or closed. A pegboard is shown in figure 2-7.