LEARNING OBJECTIVES: Discuss the purpose and procedures for proper battery alignment.

The purpose of battery alignment is to adjust all the elements of a weapons system and fire control system so that the weapons can be accurately aimed and the ordnance delivered on target. In other words, you should target the gun barrel to the exact point that the gun radar or sight is centered on.

Several things may cause your systems to be out of alignment-normal wear and tear, gun-bore erosion, improper maintenance, alterations/modifications to the system or ship, and so on. Initially, alignment is accomplished in the shipyard by the builder, but the continued accuracy of the ordnance installation relies upon constant maintenance.

SHIPYARD ALIGNMENT

The alignment of a weapons system is primarily concerned with the directions that the equipment (launchers, guns, directors, etc.) are pointed. To establish directions, you must use a definite and complete set of geometric References. The necessary References are contained in the geometric structure, called a reference frame. The reference frame consists of a reference point, a reference direction, and a reference plane.

Directions are expressed by giving instructions from a specific point. Any desired point maybe selected as the starting point, and once this selection has been made, it becomes a part of any measurement. Since this measurement must refer to the starting point, it is called the reference point.

After a reference point has been selected, it is necessary to have a reference direction from which to measure angles. The angles are measured about the reference point, starting from the reference direction. In naval ordnance, a fore-and-aft line, pointing in the direction of the ship's bow, is the most frequently used reference direction.

Angles expressing direction cannot be described completely unless a means is available for specifying the particular planes in which the angles are to be measured. This condition is met when a reference plane is selected. The horizontal plane (also called a deck plane) is one of the most commonly used reference planes. When the ship is afloat and you are comparing the horizontal plane to several other planes, two spirit levels are necessary for each comparison-the inclination of one plane with respect to another.

The three References described in the preceding paragraphs must all be used when measurements are given to describe directions. In the complete reference frame, directions are specified by two angles measured about the reference point. One angle is in the reference

direction, and the other angle is a plane perpendicular to the reference plane and is measured from the reference plane.

Before any alignment can be accomplished on a new ship, you must establish the reference frame. During the construction of a ship, one baseplate is installed within the ship's hull. This plate is referenced to a similar plate on a fixed ground installation. The plate is leveled as accurately as possible before the ship is launched, and an imaginary base plane is figured from the average readings taken from the baseplate. The foundation and the roller paths for the fire control directors, launchers, and gun mounts are machined so that they are (as nearly as possible) paralleI with the base plane. The fire control reference plane or weapons control reference plane (WCRP) is the horizontal plane to which all combat system elements are aligned. The WCRP is perpendicular to the ship's center line (SCP) and parallel to the ship base plane (SBP). In practice, it is defined by the roller path plane of one and sometimes two of the major elements of the ship's combat systems installations.

After battery alignment in train has been accomplisheed, you can begin alignment in elevation. The purpose of this alignment phase is to set all the elements so that when they are positioned in elevation with their lines of sight parallel to their own roller path plane, the elevation dials of all the elements will read zero and the elevation synchros will be at electrical zero.

So that guns, directors, and launchers can be realigned to the same position, you can provide bench marks and tram readings. Once established, tram and bench mark readings give the maintenance person a ready reference to check the alignment of the equipment. Apiece of equipment will be fitted either for tramming or with a fixed telescope for sighting a bench mark. Typically, gun mounts and missile launchers are trammed, while directors are aligned to bench marks. Some systems, however, may be fitted for both. Upon completion of initial alignment or subsequent realignment by shipyard or support activities, you must submit a shipyard alignment report to the commanding officer of the ship. Included in this report are the alignment data, tolerances, demonstration results, and any other pertinent data for all of the combat systems and subsystems aligned by shipyard personnel. This data is maintained in the Combat Systems Smooth Log.