FIN STABILIZERS
- Parent Category: Technical Articles
- In: Ship construction and Naval Architecture
- 19Nov2009
- Last Updated on Tuesday, 13 September 2011 17:16
- Published Date
- By Ramalingam
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Fin Stabilizers
In order to maintain ship's sane equilibrium condition , fin stabilizers are attached to the ship. Fin stabilizers are rectangular in shape and are always attached in pairs on each side to provide the necessary balance. The size of the fins depends on various factors such as the ship's breadth, length, displacement etc. However, compared to the ship the size of the fins is very small .
Construction and Working
Fin stabilizers are generally of retractable type, pivoted or mounted on a sliding mechanism in the ship's form. Moreover, the operating system of the fins is similar to that of a steering gear system. The movement of the fins occur when a signal from the control unit is sent. A hydraulic power unit comprising of a variable displacement pump receives the signal and provides the necessary fin movement.
However, the effectiveness of the system depends on the speed with which the fins can operate. According to international regulations the fins should rapidly move from one extreme end to the other. The shape and design of the ship should be rectangular and streamlined respectively. Most of the modern ships are provided with movable fins to facilitate a greater restoring movement to the ship.
The sensing control determines the angle of tilt of the fins and the resulting movement of the ship. For this, the control system of the stabilizers makes use of two gyroscope, one that senses the movement from the vertical and other the rolling velocity. Thus after assessing a ship's roll angle, roll velocity, roll acceleration and natural list the control system sends the signal for the right inclination angle of the fins
Thus, the fin stabilizers act rapidly to apply a righting movement to the ship, as and when it is inclined by a wave or force on side. The forward speed of the ship allows the fins to generate a thrust which results in the righting movement. However, it is to note that at low speeds the stabilizing power of the fins falls and when stationary, no stabilization is possible and the use of tank stabilizers is done for such a situation.
