Section 4 Mooring equipment

4.1.1 Anchors for positional mooring are to be sufficient in number and holding power, and are to have adequate structural strength, for the intended service. It is the Owners'/ Operators' responsibility to ensure adequate anchor holding power for each location or holding ground.

4.1.2 The anchors are to be of an approved type. Supporting calculations to verify the structural strength of the anchor under proof test loading are to be submitted.

4.1.3 The anchors are to be manufactured in accordance with the requirements of Ch 10 Equipment for Mooring and Anchoring of the Rules for the Manufacture, Testing and Certification of Materials, July 2022 (hereinafter referred to as the Rules for Materials).

4.1.4 The anchors are to be proof tested in the manner laid down in Ch 10 Equipment for Mooring and Anchoring of the Rules for Materials. The level of proof test loading for positional mooring anchors is to be the greater of the following:

1. 50 per cent of the minimum rated break strength of the intended anchor line; or

2. the value given in Table 10.1.1 Proof load tests for anchors (see Notes 1 and 2) in Rules for the Manufacture, Testing and Certification of Materials, July 2022 of the Rules for Materials.

4.2.1 Fairleads are to be designed to permit free movement of the anchor line in all mooring configurations. Figure 8.4.1 Minimum operating range and design loading of fairlead shows the minimum operating range of the fairlead to be considered in conjunction with the design load.

4.2.2 Fairleads and their supporting structures are to be designed for a load equivalent to the rated minimum break strength of the anchor line.

4.2.3 Maximum allowable stresses for the design criteria given in Pt 7, Ch 8, 4.2 Fairleads 4.2.1 and Pt 7, Ch 8, 4.2 Fairleads 4.2.2 are to be based on the following factors of safety:

Shear	1,89	Factors relate to tensile yield stress
Tension, compression or bending	1,25	Factors relate to tensile yield stress
Combined	1,11	Factors relate to tensile yield stress
(combined stress = )

Where σ_X and σ_Y are the combined axial and bending stresses in the X and Y directions respectively and τ is the combined shear stress due to torsion and/or bending in the X-Y plane.

4.2.4 Materials and steel grades are generally to comply with the requirements given in Pt 7, Ch 8, 5.2 Materials for Type P components.

4.2.5 Chain cable fairleads are to have a minimum of five pockets.

4.2.6 Wire rope fairleads are generally to have a minimum diameter of 20 times the wire rope diameter.

Figure 8.4.1 Minimum operating range and design loading of fairlead

4.3.1 Stoppers may require to be provided depending on the winch arrangements, see Pt 7, Ch 8, 5 Anchor winches and windlasses.

4.3.2 Where stoppers are fitted, they are to comply with Pt 7, Ch 8, 5 Anchor winches and windlasses in respect to mechanical and strength aspects, and Pt 7, Ch 8, 6 Electrical and control equipment for release arrangements.

4.4.1 Anchor lines are generally to be of stud link chain cable, steel wire rope or a combination of both. Special consideration will be given to proposals for the use of alternative materials.

4.4.2 Stud link chain cable is to be either of unified grade (U2 or U3) meeting the requirements of Ch 10 Equipment for Mooring and Anchoring of the Rules for Materials, or an approved special grade.

4.4.3 Wire rope for anchor lines is to have a suitable construction for its purpose (6 x 37 construction with independent wire rope core is generally acceptable).

4.4.4 Steel wire ropes are generally to comply with Ch 10, 5 Short link chain cables of the Rules for Materials, or with an equivalent recognised National or International Standard.

4.4.5 Wire rope terminal fittings are to comply with an acceptable code or standard. The strength of terminations, connecting fittings, shackles or links is not to be less than that of the anchor line.