Section 5 Anchors

5.1.1 The Rules are based on the use of high holding power (HHP) type anchors.

5.1.2 When ordinary holding power anchors are used as bower anchors, the mass given in Table 5.5.1 Anchors is to be increased by 33 per cent.

5.1.3 Where it is proposed to fit other types of anchor, the mass will be specially considered.

5.1.4 Craft other than yachts must have at least a single anchor ready for immediate deployment for any voyage or transit.

5.1.5  Yachts are to be provided with two anchors on board. Each anchor must have the rule length of chain cable attached. Only one anchor is required to be ready for immediate deployment, i.e. around the capstan. The masses of anchors may be of the following combinations:

1. The mass of the first anchor is to be not less than 100 per cent of the Rule value for the type of anchor concerned. The mass of the second anchor is to be not less than 70 per cent of the Rule value for the type concerned.

2. The mass of each anchor is to be not less than 90 per cent of the Rule value for the type of anchor concerned.

5.1.6 The fitting of a single anchor on board yachts will be specially considered. The mass of the single anchor is to be not less than 100 per cent of the Rule value for the type of anchor concerned.

5.1.7 Anchors which must be specially laid the right way up, or which require the fluke angle or profile to be adjusted for varying types of sea bed, will not generally be approved for normal craft use. In such cases suitable tests may be required.

5.1.8 Anchors are to be of an approved design. The design of all anchor heads is to be such as to minimise stress concentrations, and in particular, the radii on all parts of cast anchor heads are to be as large as possible, especially where there is considerable change of section.

5.2.1 The requirements for anchor materials are contained in the Rules for the Manufacture, Testing and Certification of Materials (hereinafter referred to as the Rules for Materials).

5.2.2 Anchors made of stainless steels or aluminium alloy may be acceptable subject to special consideration.

5.2.3 Where aluminium alloy anchors are proposed, due consideration is to be given to the compatibility of such anchors with the materials of the chain cable, anchor shackle, etc. in order to avoid galvanic corrosion.

5.3.1 Testing of anchors is to be carried out in accordance with Ch 10 Equipment for Mooring and Anchoring of the Rules for the Manufacture, Testing and Certification of Materials, July 2022.

5.3.2 For holding power testing requirements relating to high holding power anchors, see Ch 10, 1.3 Anchor holding power tests for HHP and SHHP anchors of the Rules for the Manufacture, Testing and Certification of Materials, July 2022.

5.4.1 Steel anchor shackles are to be forged or cast steel of approved manufacturer.

5.5.1 Anchors are generally to be housed in suitable hawse pipes, or stowed in dedicated chocks on deck.

5.5.2 Hawse pipes and anchor pockets are to be in accordance with Pt 3, Ch 5, 9.2 Hawse pipes and anchor recesses. Alternatively, roller fairleads of suitable design may be fitted. Where hawse pipes are not fitted, alternative arrangements will be specially considered.

5.5.3 It is recommended that anchor lashings, e.g. a ‘devil’s claw’, be fitted to hold the anchor tight against the hull or the anchor pocket. Anchor lashings are to be designed to resist at least a load corresponding to twice the anchor mass plus 10 m of cable without exceeding 40 per cent of the yield strength of the material.

5.6.1 In craft where the HHP anchor mass given in Table 5.5.1 Anchors does not exceed 2295 kg, the use of SHHP type anchors of reduced mass will be specially considered. However, the reduced SHHP anchor mass is not to be less than 67 per cent of that specified for HHP anchors in Table 5.5.1 Anchors.

5.6.2 Final acceptance will be dependent upon satisfactory strength and performance tests.

5.6.3 Anchors of designs for which approval is sought as super high holding power anchors are to be tested at sea to show that they have holding powers of at least four times those of approved standard stockless anchors of the same mass. For holding power testing requirements relating to SHHP anchors, see Ch 10, 1.3 Anchor holding power tests for HHP and SHHP anchors of the Rules for the Manufacture, Testing and Certification of Materials, July 2022.

5.7.1 The mass of each high holding power anchor given in Table 5.5.1 Anchors is for anchors of equal mass. The masses of individual anchors may vary by 7 per cent of the masses given in the Table, provided that the total mass of the anchors is not less than would have been required for anchors of equal mass.

5.8.1 Identification of anchors which have been tested is to be in accordance with Ch 10, 1.5 Forged steel anchorsof the Rules for Materials.

5.9.1 For passenger vessels and vessels not intended for the carriage of goods, the total mass P, in kg, of the bow anchor(s) is to be as prescribed by the National Authority for the intended service.

5.9.2 In the absence of specified criteria from the National Authority, the mass of high holding power anchors shall be determined as in Pt 3, Ch 5, 5.9 Anchors for vessels in service groups Zone 1 to Zone 3 5.9.3, and the mass of ordinary stockless bower anchors can be determined as in Pt 3, Ch 5, 5.9 Anchors for vessels in service groups Zone 1 to Zone 3 5.9.4.

5.9.3 Where the required mass for anchors of a design approved for the designation ‘High Holding Power’ (HHP) or ‘Super High Holding Power’ (SHHP) is used, the mass of each such anchor will be specially considered on the basis of the vessel’s characteristics and the characteristics of winds, waves and current in the proposed operation area.

5.9.4 For ordinary stockless bower anchors and in the absence of relevant criteria by the National Authorities, the mass of ordinary stockless bower anchors can be calculated in accordance with the criteria given in the Rules and Regulations for the Classification of Inland Waterways Ships, July 2022, Pt 3, Ch 12, 5 Equipment.