Primary steering control is provided by a hydraulic
(HBCS). The HBCS consists of the following three
actuator that vectors the hullborne steering nozzles in
r e s p o n s e to position commands from the helm.
1. Hullborne steering system
Additional directional control is provided by the thrust
2. Heading hold system
reversers on the hullborne propulsory. A bow thruster is
included in this system to allow for improved low-speed
3. Hullborne throttle system
maneuverability and to assist in docking. The capability
Operation of the HBCS takes place almost entirely
for strut steering is also included in this system. In the
from the pilothouse, as shown in figures 7-27 and 7-28.
foils down mode, for example, the forward strut can be
The only HBCS controls located in the EOS are the
swiveled for hullborne steering.
throttle assembly and the throttle transfer module
assembly. These assemblies are used in conjunction
Heading Hold System
with the foilborne control system. Let's take a brief look
at the three subsystems of the HBCS.
The heading hold system provides the PHM with
the capability of automatically maintaining a preset
Hullborne Steering System
heading while the craft is in either the hullborne or
foilborne propulsion mode. The helmsman establishes
The hullborne steering system provides directional
a preset heading command. A heading error signal is
developed as a difference occurs between the craft's
control and maneuvering capability while the PHM is
in the hullborne mode. The location of each major
gyrocompass and the preset heading command from the
helmsman. A steering correction signal is then applied
equipment item in the hullborne steering system is
to the ACS or hullborne steering system.
shown in figure 7-28.
Figure 7-28.--Hullborne steering system equipment.