Section 19 Fin stabilisers

19.1.1 For requirements relating to fin stabiliser scantlings, arrangements, foundations, supporting structure and watertight integrity, see Vol 1, Pt 3, Ch 3, 1 General.

19.1.2 Fin stabiliser actuating systems are to be consistent with the requirements of Vol 2, Pt 6, Ch 1, 5 Design and construction as applicable.

19.1.3 Materials for components of fin stabilisers are to be consistent with the requirements of Vol 2, Pt 6, Ch 1, 3 Materials as applicable.

19.1.4 Control and electrical engineering systems are to comply with the requirements of Vol 2, Pt 9 Electrotechnical Systemsand Vol 2, Pt 10 Human Factors respectively as applicable.

19.2.1 Fin stabilisers are to be capable of satisfying the specified functional performance requirements as detailed in the System Design Description, see Vol 2, Pt 1, Ch 3, 3.3 Calculations and specifications 3.3.13.

19.2.2 For retractable type fin stabilisers, the servo system arrangements are to be capable of extending the fins fully at the ship's maximum service speed and in the most onerous environmental conditions, for which the ship is designed, see Vol 1, Pt 5, Ch 2, 2.3 Wave environment.

19.2.3 After setting to work, the fin stabiliser system is to be entirely automatic irrespective of ship speed or sea state.

19.2.4 Where provision is made for an automatic forced roll facility, the roll amplitude and period are to be manually adjustable. Forced induction of rolling motion is not to result in an unsafe condition for the ship, equipment or the crew. The arrangements are also to satisfy the following:

1. An automatic forced roll facility is to be selectable by a switch located on the navigating bridge which is located or protected so as to prevent inadvertent operation of this function.

2. Controls are to be provided on the navigating bridge to manually adjust the amplitude and periodicity of the induced rolling.

19.2.5 Failure of any part of the fin stabiliser unit or its control system is not to result in an unsafe condition which will have detrimental effect on the ship's operating or sea-keeping capability.

19.2.6 In the event of failure of the fin actuating system, a hand pump is to be provided, mounted in a readily accessible position, which is capable of moving the fin to a known position and securing it in that position in the absence of electrical power, and being operated by no more than two men when the ship is stopped.

19.2.7 Consideration is to be given to hydraulic locking or any other condition where the equipment becomes mechanically locked and cannot be operated. Where the possibility of hydraulic locking cannot be avoided, a clear indication of hydraulic lock is to be provided at the stabiliser control position.

19.3.1 Fin stabiliser actuating control arrangements are to be located in readily accessible positions that have means of communication provided to the machinery control station and the navigating bridge.

19.3.2 Fin stabiliser function indicators are to be provided on the navigating bridge and at the main machinery control station.

19.3.3 The fin position feedback signals are to be independent of the actuating systems.

19.3.4 Alarms and monitoring requirements are indicated in Table 3.19.1 Alarms and monitoring.

19.3.5 All alarms associated with fin stabiliser faults are to be indicated on the navigating bridge and in accordance with the requirements of Vol 2, Pt 9, Ch 7 Control, Alerts and Safety Systems.

19.4.1 After installation on board the fin stabiliser unit is to be subject to hydrostatic and running tests.

19.4.2 Testing and trials are to be carried out in accordance with procedures that have been agreed between the Shipyard, Owner/Operator and LR. The testing is to demonstrate:

1. The stabiliser system including the functional performances specified in the System Design Description required by Vol 2, Pt 1, Ch 3, 3.3 Calculations and specifications 3.3.13.

2. Extending and retracting the fins.

3. Alternative electrical power supply arrangements where provided and functional capability of the emergency hand pump arrangements.

4. Stabiliser controls.

5. The alarms and indicators.

6. Where the stabiliser system is designed to avoid hydraulic locking, this feature is to be demonstrated.