Figure 4-14.--Effect of weights on the gyroscope.
SPERRY MK 23 GYROCOMPASS
acceleration and deceleration. There are several
methods used to do this. The method used depends on
the type of gyrocompass. For further information on the
The Sperry Mk 23 gyrocompass is a small electrical
compass that is used aboard many naval vessels to
method of damping used in the gyrocompasses installed
furnish heading data. On many of the small combatant
on your ship, refer to the applicable manufacturer's
vessels and larger auxiliary vessels, it is used as the
master compass. On some of the larger combatant
vessels, it is used as a backup compass. The compass is
capable of indicating true north accurately in latitudes
up to 75°N or S. The compass also can be used as a
directional gyro when nearer the poles.
There are a wide variety of gyrocompass systems
Unlike the mechanical gyrocompass, which uses
i n s t a l l e d on Navy ships in the fleet today.
weights that are affected by gravity to cause the desired
G y r o c o m p a s s e s are identified by the mark
period of damping, the Sperry Mk 23 gyrocompass uses
(Mk)modification (Mod) system. The Mk number
a special type of electrolytic bubble level (gravity
designates a major development of a compass. The Mod
reference), which generates a signal proportional to the
tilt of the gyro axle. This signal is then amplified and
number indicates a change to the major development.
applied to an electromagnet which applies torque about
The most common type of gyrocompasses found in the
the vertical and/or horizontal axes to give the compass
fleet today are the electrical gyrocompass systems, such
the desired period and damping. The gyrocompass is
as the Sperry Mk 23, Sperry Mk 27, and the Sperry Mk
compensated for speed error, latitude error, unbalance,
19 Mod 3.
and supply voltage fluctuations. An electronic follow-up
system furnishes accurate transmission of heading data
There are also two new gyrocompass systems
to remote indicators.
currently being installed on Navy ships today. These are
The original Sperry Mk 23 gyrocompass (Mod O)
the Stabilized Gyrocompass Set AN/WSN-2 and the
has had several minor modifications and one major
Inertial Navigation Set AN/WSN-5. Operation of the
modification (Mod C-3). Only the Mk 23 Mod O and
A N / W S N - 5 is classified; therefore, only the
the Mk 23 Mod C-3 will be discussed in this training
ANAVSN-2 will be discussed in this training manual.