The gyrocompass was developed as the answer to the need for an
instrument that would indicate TRUE NORTH rather than MAGNETIC
NORTH. The gyrocompass is now the main source for determining
The basis for the gyrocompass is the
gyroscope. A rapidly spinning body
having three axes of angular freedom
constitutes a gyroscope. This may be
illustrated by the heavy wheel rotating at
high speed in supporting rings or
The gyrocompass must be lit off a
minimum of 4 hours prior to use. This
allows the gyro to warm up and settle.
It is desirable to lite off the
gyrocompass 24 hours prior to the
scheduled underway time.
Figure 2-11. Gyroscope.
The gyrocompass is powered by electricity and consists of two main
They are the master gyro and repeaters. The master
gyrocompass consists of a control cabinet, power supply, speed unit,
alarm unit, and transmission units. It is normally located within the
ships hull where it is least affected by pitch, roll, yaw, and battle
damage. The IC electricians are responsible for its upkeep.
A properly functioning gyrocompass will often have a mechanical error
of 2° or less. The gyrocompass must be checked for error at least once
daily while the ship is under way.