Section 1 Survey requirements

1.1.1 The information in this Appendix is intended to provide guidance to Owners and Surveyors for the inspection of classed positional mooring systems as defined in Chapter 10.

1.2.1 Annual Surveys are to be carried out in accordance with Pt 1, Ch 3 Periodical Survey Regulations with the vessel at its normal operational draft with the positional mooring system in use.

1.2.2 The purpose of the Annual Survey is to confirm that the mooring system will continue to carry out its intended purpose until the next Annual Survey. No disruption of the unit's operation is intended. Where practicable the Annual Survey is to be carried out during a relocation move.

1.2.3 The scope of the Annual Survey is limited to the mooring components adjacent to winches, windlasses and fairleads. Depending on the mooring component visible from the unit, particular attention should be given to:

1. Chain:
   • Wear in the chain shoulders in way of the chain stopper, windlass pockets and fairleads.
   • Support of chain links in the windlass pockets.
2. Wire rope:
   • Flattened ropes.
   • Broken wire.
   • Worn or corroded ropes.

1.2.4 The Surveyor should examine the maintenance records and determine if any problems have been experienced with the mooring system in the previous twelve months, e.g., breaks, mechanical damage, loose joining shackles, and chain or wire jumping.

1.2.5 Should the Annual Survey reveal severe damage or neglect to the visible chain or cable, a more extensive survey will be required by Lloyd’s Register (hereinafter referred to as ‘LR’).

1.2.6 Typical damage warranting a more comprehensive survey would include:

1. Chain:
   • Reduction in diameter exceeding 75 per cent of the margin assumed in the design, see Pt 3, Ch 10, 8.2 Corrosion and wear
   • Missing studs.
   • Loose studs in Grade 4 chain.
   • Worn lifters (i.e., gypsies) causing damage to the chain.

2. Wire rope:

   • Obvious flattening or reduction in area.
   • Worn cable lifters causing damage to the wire rope.
   • Severe wear or corrosion.

1.3.1 Special Periodical Surveys are to be carried out at five-yearly intervals in accordance with Pt 1, Ch 3 Periodical Survey Regulations, and will require extensive inspection, usually associated with a sheltered water visit. When considered necessary by LR the interval between Special Periodical Surveys may be reduced.

1.3.2 The purpose of the Special Survey is to ensure that each anchor line is capable of performing its intended purpose until the next Special Survey, assuming that appropriate care and maintenance is performed in the mooring system during the intervening period.

1.3.3 The Special Survey should include:

1. Close visual inspection (100 per cent) of mooring chains, with cleaning as required.
2. Enhanced representative NDT sampling.
3. Dimension checks.

1.3.4 Particular attention is to be given to the following:

• Cable or chain in contact with fairleads, etc.
• Cable or chain in way of winches, windlass and stoppers.
• Cable or chain in way of the splash zone.
• Cable or chain in the contact zone of the sea bed.
• Damage to mooring system.
• Extent of marine growth.
• Condition and performance of corrosion protection.

1.3.5 This survey is to ensure that the lengths of anchor line frequently in contact with winches, windlasses and fairleads are suitably rated for this application.

1.3.6 Joining shackles are to be examined for looseness and pin securing arrangements. All joining shackles of the Kenter type and bolted type which have been in service for more than four years should be dismantled and an MPI performed on all machined surfaces as per Pt 3 Ch 19.2.

1.3.7 Visual surveys of all windlass and fairlead chain pockets are to be carried out with particular attention to the following:

• Unusual wear or damage to pockets.
• Rate of wear on pockets including relative rate of wear between links and pockets.
• Mismatch between links and pockets, and improper support of the links in the pockets.

1.3.8 The thickness (diameter) of approximately one per cent of all chain links should be measured. The selected links should be approximately uniformly distributed through the working length of the chain. The above percentage may be increased/decreased if the visual examination indicates excessive/minimal deterioration.

1.3.9 A functional test of the mooring system during anchor-handling operation is to be carried out with particular attention given to the following:

• Smooth passageway of chain links and or/wire rope and joining shackles over the windlass and fairleads pockets.
• The absence of chain jumping or other irregularities.

1.4.1 As an alternative to the Special Survey, the Owner may agree with LR that the Special Survey may be carried out on a continuous survey basis by providing an extra mooring line which may be regularly inspected on shore and exchanged with lines installed on the unit in accordance with an appropriate schedule.