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)
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