The function of a fin stabilizer, found at the bottom part of the ship’s hull, is to provide resistance to the excess rolling of the ship in either direction.
Many seafarers have not seen a real fin stabilizer until the ship goes to a dry dock for hull inspection and surveys. This does not rule out the knowledge that every onboard engineer and officer must possess regarding the components and functioning of the fin stabilizer system.
1. Two fins form part of the hull structure of the ship, one port, and one starboard. These fins are connected to the fin stabilizer room on the port and starboard sides of the ship from where they are operated/ controlled. Each stabilizer consists of a fin box, which houses a fin and supports the fin-actuating machinery. Each stabilizer machinery unit provides the support and the means by which the fin may be rigged in or out, locked, and tilted up to +/-25 degrees.
2. Two hydraulic power units located in the stabilizer room PS and SB, power the fin tilting and rigging motions.
3. Bridge Control Panel (BCP) provides control and indicators for remote operation from the bridge. The panel is installed in the BMCC.
4. Two local control units (LCU) are located in each stabilizer’s room. These panels are providing local indication and control of the fin.
5. Main Control Unit (MCU) –This panel can control fins from ECR with the same features as a bridge control unit. LCU display for starboard and port is present in MCU.
6. Roll Motion Sensor Unit (RMSU) measures the ship’s roll acceleration and provides the control signal for the roll control algorithm and interfaces to the Main Control Unit (MCU). The RMSU comprises a solid-state sensor and signal-conditioning electronics. The sensor is located in MCU.
7. Fin Angle Feedback Transmitter provides the fin angle position signal for the servo controller. A fin angle indicator is mechanically coupled to the tilt cylinder piston rod and the fin angle transmitter shows the fin tilt angle.
8. The Stroke Control Unit (SCU) is mounted on the variable delivery pump. It provides drive and feedback on the position of the pump’s control spindle.