Clasification Society Rulefinder 2016 - Version 9.25
Clasification Society Rules and Regulations - Rules and Regulations for the Classification of Offshore Units, January 2016 - Part 3 FUNCTIONAL UNIT TYPES AND SPECIAL FEATURES - Chapter 10 Positional Mooring Systems - Section 12 Electrical and control equipment

Section 12 Electrical and control equipment

Parent topic: Chapter 10 Positional Mooring Systems

12.1 General

12.1.1 The electrical installation is to be designed, constructed and installed in accordance with the relevant requirements of Pt 6, Ch 2 Electrical Engineering

12.1.2 Control, alarm and safety systems are to be designed, constructed and installed in accordance with the relevant requirements ofPt 6, Ch 1 Control Engineering Systems, together with the requirements of 12.2 to 12.4.

12.1.3 Reference should be made to the general requirements ofPt 3, Ch 10, 13 Thruster-assisted positional mooring for thruster-assisted positional mooring systems.

12.2 Controls, indications and alarms

12.2.1 Adequate control, indication and alarm systems are to be provided to ensure satisfactory operation of the positional mooring system.

12.2.2 A suitable central control station is to be provided.

12.2.3 Where additional local control stations are provided, means of direct communication between the local and central control stations are to be arranged.

12.2.4 Indication of the following, as applicable, is to be provided at the central control station, and where local control is provided, at the local control station:
  1. Position of unit.
  2. Heading of unit.
  3. Anchor line tensions.
  4. Wind speed and direction.
  5. Offloading tanker status:
    • position.
    • heading.
    • hawser tension.
    • offloading hose connections status.
12.2.5 Alarms are to be provided for the following fault conditions, as applicable:
  1. Deviation from positional limits.
  2. Deviation from heading limits.
  3. Deviation from anchor line tension limits (high and low).
  4. Gyro compass fault.
  5. Position reference system fault.
  6. Wind speed and direction indicator fault.
  7. Offloading tanker deviation from attached limits.
  8. Control computer system fault.
  9. Turret/unit relative heading limit exceedence.

12.3 Control aspects – Disconnectable mooring systems

12.3.1 This sub-Section is applicable to units or ships which are disconnectable to avoid hazards or severe storm conditions.

12.3.2 Power, control and thruster systems and other systems necessary for the correct functioning of the positional system are to be provided and configured such that a fault in any active component will not result in a loss of position.

12.3.3 At least two automatic control systems are to be provided and arranged to operate independently.

12.3.4 Adequate controls are to be provided at the control station for satisfactory operation of the connect/disconnect mechanism.

12.3.5 Hydraulic and electrical systems are to be served by two means of power supply. Failure of the main supply is to activate an alarm.

12.3.6 Where the mooring system is designed on the basis of the unit or ship disconnecting at limiting environmental levels below the 100-year extreme case required by 4.3, means are to be provided to enable the rapid release of the unit or ship as applicable from the mooring system in an emergency. The quick-disconnect system is to be based on single operation at the control station, and may be independent of the normal control system.

12.3.7 Suitable fail-safe measures are to be provided to prevent inappropriate or inadvertent disconnection of the mooring system.

12.3.8 The reconnection of a disconnectable unit or ship is to be to the satisfaction of LR Surveyors.

12.4 Controls of winch and windlass systems

12.4.1 This sub-Section is applicable to mooring systems incorporating winches, windlasses, etc., which are used to actively control and adjust anchor line tensions in-service, or to release anchor lines in an emergency.

12.4.2 Adequate controls are to be provided at the local control station for satisfactory operation of the winch(es).

12.4.3 The braking system is to be arranged so that the brakes, when applied, are not released in the event of a failure of the normal power supply.

12.4.4 Standby power is to be provided to enable winch brakes to be released within 15 seconds in an emergency. The release arrangements are to be operable locally at each winch and from the central control position, and are to be such that the entire anchor line can be lowered in a controlled manner.

12.4.5 The standby power is to be such that during lowering of the anchor line it is possible to apply the brakes once and then release them again in a controlled manner.

12.4.6 Standby power is to be provided so that any anchor line stoppers or pawl mechanisms may be released from either the local or central control stations up to a line tension equal to the minimum rated break strength of the anchor line. These mechanisms are to be capable of release at the maximum angles of heel and trim under the damage stability and flooding conditions for which the unit is designed.

12.4.7 At least one position reference system and one gyrocompass or equivalent is to be provided, when applicable, to ensure the specified area of operation and heading deviation can be effectively monitored.

12.4.8 Position reference systems are to incorporate suitable position measurement techniques which may be by means of acoustic devices, radio, radar, taut wire, riser angle, gangway extension and angle or other acceptable means, depending on the service conditions for which the unit is intended.

12.4.9 A vertical reference sensor is to be provided, if applicable, to measure the pitch and roll of the unit.

12.4.10 Means are to be provided to ascertain the wind speed and direction acting on the unit.

12.4.11 The operation of winches, windlasses and associated brakes, chain stoppers and pawls is to be controlled locally from weather protected control stations which provide good visibility of the equipment and associated anchor handling operations.

12.4.12 A central control station, which may be located on the bridge or a separate manned control room, is to be provided from which brakes, chain stoppers and pawls can be remotely released.

12.4.13 For each anchor winch the respective local control station is to be provided with a means of indicating the following:
  1. Line tension.
  2. Length of line paid out.
  3. Line speed.
12.4.14 The indication required by 12.4.13(a), and (b), is to be repeated to the central control station and in addition a means of indicating the following is to be provided at this position:
  1. Mooring patterns and anchor line catenaries.
  2. Status of winch operation.
  3. ition and heading, see also 12.4.7.
  4. Gangway angle and extension, when applicable.
  5. Riser angle, when applicable.
  6. Wind speed and direction, see also 12.4.10.

12.4.15 Means of voice communication are to be provided between the central control station, each local control station and anchor handling vessels, when applicable.

12.4.16 Alarms are to be provided at the local and central control stations for the following fault conditions:
  1. Excessive line tension.
  2. Loss of line tension.
  3. Excessive gangway angle and extension, when applicable.
  4. Excessive riser angle, when applicable.

12.4.17 Alarms are to be provided adjacent to the winches and windlasses to warn personnel prior to and during any remote operation.

12.4.18 Alarms are to be provided at the central control station for the following fault conditions:
  1. When the unit deviates from its predetermined area of operation.
  2. When the unit deviates from its predetermined heading limits.

These alarms are to be adjustable but should not exceed specified limits. Arrangements are to be provided to fix and identify their set points.

Copyright 2016 Clasification Society, International Maritime Organization, International Labour Organization or Maritime and Coastguard Agency. All rights reserved. Clasification Society, its affiliates and subsidiaries and their respective officers, employees or agents are, individually and collectively, referred to in this clause as 'Clasification Society'. Clasification Society Register assumes no responsibility and shall not be liable to any person for any loss, damage or expense caused by reliance on the information or advice in this document or howsoever provided, unless that person has signed a contract with the relevant Clasification Society entity for the provision of this information or advice and in that case any responsibility or liability is exclusively on the terms and conditions set out in that contract.