Drawing Lines

Figure 1-71.—Blueprint title block (A) Naval Ship’s Systems Command; (B) Naval Facilities Engineering Command. Some companies use odd numbers for right-hand parts and even numbers for left-hand parts. Drawing Lines The lines used in working drawings are more than a means of showing a picture of an object for the purpose of building or repairing. The way a line is drawn has a definite meaning. Thick lines are used for the visible outline of the object being drawn. Medium lines are used for the dotted lines representing hidden features and for cutting-plane, short-break, adjacent-part, and alternate-position lines. Center lines, dimension lines, long-break lines, ditto lines, extension lines, and section lines are represented by thin lines. To understand blueprint reading, you must know the different types of lines used in general drawing practice and the information conveyed by each. Some of the lines of major importance are illustrated in figures 1-72-A and 1 -72-B. The correct uses are illustrated in figure 1-73. Blueprints make it possible to understand, in a comparatively small space, what is to be made or repaired. Of the many types of blueprints you will use aboard ship, the simplest one is the plan view. ‘his type of blueprint shows the position, location, and use of the various parts of the ship; for example, to find the battle stations, sickbay, barbershop, or other parts of the ship. In addition to plan views, other blueprints, called assembly prints, unit or subassembly prints, and detail prints, show various kinds of machinery and mechanical equipment. Assembly prints show the various parts of the mechanism, how the parts fit together, and their relation to each other. Subassembly prints show the 1-44