In addition to the general requirements contained in resolution
A.694(17)footnote, heading control systems
should comply with the following minimum performance requirements.
2.1 Within limits related to the ship's manoeuvrability
the heading control system, in conjunction with its source of heading
information, should enable a ship to keep a preset heading with minimum
operation of the ship's steering gear.
2.2 A heading control system may work together
with a track control system adjusting its heading for drift.
2.3 A turn rate control for performing turns may
be provided.
3
Functional Requirements
3.1
Adaption to steering characteristics
and environmental conditions
The heading control system should be capable of adapting
manually or automatically to different steering characteristics of
the ship under various speed, weather and loading conditions, and
provide reliable operation under prevailing environment and normal
operational conditions.
The heading control system should be able to perform turns,
within the turning capability of the ship, based either on a preset
turning radius or a preset rate of turn.
3.3
Rudder angle limitation
Means should be incorporated in the equipment to enable
rudder angle limitation in the automatic mode. Means should also be
available to indicate when the angle of limitation has been commanded
or reached. When other means of directional control are used the requirements
of this section should appropriately apply.
Means should be incorporated to prevent unnecessary activation
of the rudder due to normal yaw motion.
Any alteration of the preset heading should not be possible
without intended action of the ship's personnel.
3.6
Limiting of overshoot
The heading control system should change to a preset heading
without significant overshoot.
4
Change-Over from Automatic to Manual Steering
and Vice Versa
4.1 Change-over from automatic to manual steering
and vice-versa should be possible at any position of the rudder and
should be effected by one manual control within 3 seconds.
4.2 Change-over from automatic to manual steering
should be possible under any conditions including any failure in the
automatic control system.
4.3 When changing over from manual to automatic
steering the heading control system shall take over the actual heading
as the preset heading.
4.4 There should be a single change-over control
which should be located in such a position that it is easily accessible
to the officer of the watch.
4.5 Adequate indication should be provided to
show which method of steering is in operation.
5
Change-Over from Track Control to Heading
Control
5.1 If the heading control system works as part
of a track control system, then when switching from track control
to heading control, the actual heading should be taken as the preset
heading.
5.2 Any switching back to track control shall
not be possible without intended action of the ship's personnel.
6
Alarms and Signalling Facilities
6.1
Failure or reduction in power
An alarm both audible with mute function and visual should
be provided in order to indicate failure or a reduction in the power
supply to the heading control system or heading monitor which would
affect the safe operation of the equipment.
An off-heading alarm, both audible with mute function and
visual should be provided when the actual heading deviates from the
preset heading beyond a preset limit.
If the ship is required to carry two independent compasses,
a heading monitor should be provided to monitor the actual heading
information by independent heading sources. The heading monitor is
not required to be an integrated part of the heading control system.
An alarm both audible with mute function and visual should be
provided when the heading information in use deviates from the second
heading source beyond a preset limit.
6.4
Indication of heading source
A clear indication of the actual heading source should be
provided.
The heading control system should provide an indication
when any input from external sensors used for control is absent. The
heading control system should also repeat any alarm on the status
messages concerning the quality of the input data from its external
sensors when they are used for control.
7.1 The number of operational controls should
be such that easy and safe operation can be achieved. The controls
should be designed to preclude inadvertent operation.
7.2 Unless features for automatic adjustment are
incorporated in the installation, the heading control system should
be provided with adequate controls to adjust to effects due to weather
and the ship's steering performance.
7.3 The heading control system should be designed
in such a way as to ensure altering the pre-set heading to starboard
by turning the heading setting control clockwise or tilting it to
the right-hand side. Normal alterations of heading should be possible
by one adjustment only of the preset heading control.
7.4 Where remote control stations are provided,
facilities for the delegation of control to the remote station and
unconditional return of control should be incorporated in the master
station.
7.5 Except for the preset heading setting control,
the actuation of any other control should not significantly affect
the heading of the ship.
7.6 Additional controls at remote positions should
comply with the provisions of this performance standard.
8.1 The heading control system should be connected
to a suitable source of heading information.
8.2 The heading control system should be connected
to a suitable source of speed information when it is used in a turning
radius mode or when any control parameters are automatically adapted
to speed.
8.3 If a heading control system is capable of
digital serial communication with the ship's navigation system then
the interface facilities should comply with the relevant international
marine interface standards.footnote