Description
Principle
he rudder blade rotates → driving the transmitter unit → generating an angular electrical signal → processed by the transmission unit → sent to the indicator unit → driving the pointer or digital display to show the current rudder angle.
This system is a crucial equipment for ensuring the safety of ship navigation, enabling the steering personnel to grasp the position of the rudder blade in real-time and accurately, thereby achieving precise course control.
Core Unit
1. Sensor/transmitter unit
• Installation location: Inside the steering gear compartment, near the rudder stock or steering gear, directly linked to the rudder stock through a mechanical linkage.
• Core function: Sensing the actual physical rotation angle of the rudder blade and converting it into transmittable electrical signals (such as resistance changes, voltage signals, digital coding signals, etc.).
• Common types include: potentiometer type, synchro type (synchronous generator type), photoelectric encoder type, etc.
2. Signal processing and transmission unit
• Function: Amplify, filter, and perform analog-to-digital conversion on the raw electrical signals output by the transmitter, and reliably transmit standardized signals (such as 4-20mA, 0-10V, digital serial signals) to the bridge and other locations where display is required through cables.
3. Indicator/display unit
• Installation location: It is primarily installed on the bridge (the instrument panel in front of the steering wheel), and may also be installed in the steering gear compartment, emergency steering position, captain's room, or pilot workstation.
• Core function: Receive and interpret the transmitted signal, and convert it into intuitive rudder angle readings for display.
• Pointer type: The most common type, it employs a circular dial with zero position (straight ahead) in the middle, and scales marked on the left and right (usually ±35° or ±40°), with the angle indicated by a pointer.
• Digital type: Display the angle value directly through an LCD screen or a digital display.
• Combination type: Display combining numbers and pointers.
• Shape classification: Based on installation and observation requirements, it can be divided into single-sided and three-sided types (facilitating observation from multiple directions).
Positioning and Function
• Location: It is fixedly installed in the most prominent position on the bridge helm station, typically facing the steering wheel or integrated onto the comprehensive control panel.
• Core function: Display the actual deflection angle of the rudder blade relative to the ship's fore-and-aft line in real-time and intuitively, enabling steering personnel to precisely execute steering commands, monitor whether the response of the steering gear to the commands is accurate and timely, and promptly detect faults in the steering system (such as discrepancies between the indicated angle and the command, or no change in the rudder angle).
Characteristics and Types
1. Display mode
• Analog type: The most traditional and reliable, featuring a circular dial with zero position (straight ahead) in the middle, and 35° or 40° scales marked on each side. The pointer indication is clear and intuitive.
• Digital type: Display the angle value directly on an LED or LCD screen, providing precise readings.
• Combined type: It features both analog and digital displays, balancing intuition and precision.
2. Exterior design
• Three-sided indicator: This is the most typical configuration on the wheel house. The indicator has display surfaces on the front and both sides, ensuring that the driver can read the rudder angle without obstruction, whether standing directly in front of, on the left side of, or on the right side of the steering wheel. This is crucial for navigation safety.
• Single-sided indicator: Typically used as an auxiliary display or installed in areas where space is limited.
3. Signal input
Receive standard electrical signals transmitted via cables from sensors in the steering gear compartment and drive the pointer or digital display.
The rudder angle indicator is a key visual bridge connecting the "helmsman's command" and the "actual action of the rudder blade". According to international conventions such as SOLAS and classification society regulations, its work must be accurate and reliable, and it is necessary to regularly compare and calibrate with the actual steering angle of the machinery in the steering cabin to ensure zero error display.
