CHAPTER 4 SHIP’S INPUT SYSTEMS A ship’s input system is defined as a system that provides  an  essential  input  to  an  equipment  or  another system and is maintained by the Electronics Technicians (ETs).   These   input   systems   receive   data   from equipment generally maintained by another department, such as engineering. The data is distributed throughout the ship to other users as well as engineering. Many of these  systems  are  on  board  Navy  ships. In   this   chapter,   we   will   discuss   the   basic gyrocompass  system  and  the  basic  underwater  log system.  Because  these  two  systems  are  the  sole responsibility  of  the  engineering  department  and unauthorized personnel are not permitted access to them, no attempt will be made to teach the maintenance of these systems. Only a brief description of the overall system  will  be  provided.  This  knowledge  will  assist  you with a better understanding of the ship’s input to your equipments  and  systems  especially  during  trouble- shooting. GYROCOMPASS SYSTEMS The gyrocompass provides a means of determining ownship’s  heading,  roll,  and  pitch  of  the  ship. Gyrocompass systems include the Mk 19, Mk 23, Mk 27,   and   AN/WSN-2.   The   gyrocompass   system transmits  information  to  weapons  control,  sonar,  radar, degaussing, depth control, dead reckoning and other equipment or systems as required. Components of the gyrocompass  system  include:  gyrocompass  control Cabinets,  power  supply,  indicators  for  ship’s  heading, roll,  and  pitch  (analog  and  digital),  synchro  signal amplifiers,  and  synchro  signal  converters.  Normally  the Interior  Communications  Technician  (IC)  and Electrician’s Mate (EM) will maintain this equipment. Gyrocompasses are identified by the mark (Mk) modification   (Mod)   system.   The   Mk   number designates a major development of a compass. The Mod   number   indicates   a   change   to   the   major development.  Two  new  gyrocompass  systems  are currently being installed on Navy ships. These are the stabilized  Gyrocompass  Set  AN/WSN-2  and  the  Inertial Navigation  Set  AN/WSN-5.  We  will  briefly  discuss both in this chapter. MK 19 GYROCOMPASS The Mk 19 gyrocompass seeks and continuously indicates the degree of the ship’s roll, pitch, and heading. The Mk 19 gyrocompass furnishes precise synchro roll, pitch,  and  heading  data  for  use  in  navigation equipments. It also is used in stabilizing surveillance, sub-surface  search  (sonar),  surface  search,  air  search, navigation, and fire control radar systems. The Mk 19 gyrocompass   consists   of   four   major   components: master  compass,  control  cabinet,  failure  annunciator, and power supply as shown in figure 4-1. The Mk 19 gyrocompass  system  is  installed  aboard  warships (submarines,   DD   types,   and   larger),   amphibious warships (LSDs and larger), auxiliary ships (longer than 91 meters (300 feet), patrol ships (FF types and larger), and mine warfare ships. Output Signals These  Mk  19  gyrocompass  provides  the  following output signals: heading (1X, 36X synchro), roll and pitch (2X, 36X synchro). The heading data is provided on two different buses: normal and critical. To prevent overload of the static power supply when operating on battery  power,  the  normal  bus  is  disconnected  and  only those indicators on the critical bus remain operational. Heading  Indicators Heading  indicators  display  ownship’s  heading information  received  from  the  ship’s  gyrocompass system. The indicators may be either synchro-servo or digital indicators. The indicator may be single (1X) or combined  single  and  thirty-six  (1X,  36X)  speeds. Thirty-six   speed   indicators   are   used   for   precise readings.  Digital  indicators  provide  a  three-digit, solid-state, readout of ship’s heading with a range of 000 to 359 degrees in one-degree increments. Single  and  thirty-six  (1X,  36X)  speed  indicators  are provided in areas such as: AFT  Steering—each  trickwheel  and  emergency steering Pilot  House—ship  control  console,  OOD steering,  and  bridge  wings  (pelorus) 4-1