Section 5 Anchor cable
Clasification Society 2024 - Version 9.40
Clasifications Register Rules and Regulations - Rules and Regulations for the Classification of Naval Ships, January 2023 - Volume 1 Ship Structures - Part 3 Design Principles and Constructional Arrangements - Chapter 5 Anchoring, Mooring, Towing, Berthing, Launching, Recovery and Docking - Section 5 Anchor cable

Section 5 Anchor cable

Parent topic: Chapter 5 Anchoring, Mooring, Towing, Berthing, Launching, Recovery and Docking

5.1 General

5.1.1 Anchor cable may be of stud link chain, short link chain or wire rope, subject to the requirements of this Section.

5.1.2 An easy lead of the cables from the windlass to the anchors and chain lockers is to be arranged.

5.2 Chain cable and chain locker

5.2.1 The length and diameter of chain cable is to be as indicated in Table 5.4.1 Equipment - HHP Bower anchors and chain cables. The total length of chain cable given in Table 5.4.1 Equipment - HHP Bower anchors and chain cables is to be divided into approximately equal parts between the two bower anchors.

5.2.2 Typically for vessels with equipment number up to 90 calculated in accordance with Vol 1, Pt 3, Ch 5, 2.1 Equipment Number calculation, short link chain cable may be accepted provided that the breaking load is not less than that of stud link chain cable of the diameter required by Table 5.4.1 Equipment - HHP Bower anchors and chain cables

5.2.3 Where wire rope is used in lieu of chain cable for anchoring, galvanised wire rope with an independent wire core in accordance with Ch 10, 6 Steel wire ropes of the Rules for the Manufacture, Testing and Certification of Materials, July 2022 is to be used. 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.

5.2.4 Chain cables are to be steel in accordance with the requirements of Ch 10 Equipment for Mooring and Anchoring of the Rules for Materials.

5.2.5 Grade U1 material having a tensile strength of less than 400 N/mm2 is not to be used in association with high holding power anchors. Grade U3 material is to be used only for chain 20,5 mm or more in diameter.

5.2.6 In addition to Vol 1, Pt 3, Ch 5, 5.2 Chain cable and chain locker 5.2.4 special consideration will be given to the use of chain cable of alloy steel. Alloy steel is to be of a suitable type, details of which are to be submitted for consideration.

5.2.7 The form and proportion of links and shackles are to be in accordance with Ch 10 Equipment for Mooring and Anchoring of the Rules for Materials.

5.2.8 Where kedge anchors are used in association with chain cable, this cable may be either stud link or short link.

5.2.9 Test certificates issued in accordance with Ch 10 Equipment for Mooring and Anchoring of the Rules for Materials are to be signed by the Surveyors when the cables are placed on board the ship.

5.2.10 Arrangements are to be provided for the safe use of cable when mooring to a buoy, securing alongside hazardous or exposed jetties or preparing to be towed. Alternative arrangements to meet these requirements without the use of cable are to be submitted for consideration.

5.3 Wire rope

5.3.1 Steel wire ropes are to be manufactured, tested and certified as required by Ch 10 Equipment for Mooring and Anchoring of the Rules for Materials.

5.4 Cable clench

5.4.1 Provision is to be made for securing the bitter end of the chain cable to the ship structure. The fastening for securing the bitter end is to be capable of withstanding a force of not less than 15 per cent and not greater than 30 per cent of the minimum breaking strength of the as fitted chain cable. It is to be provided with suitable means such that, in case of emergency, the chain cable may be easily slipped to sea from an accessible position outside the chain cable locker. Where the mechanism for slipping the chain cable to sea penetrates the chain locker bulkhead, this penetration is to be made watertight.

5.4.2 Alternatively the cable end connection may be accepted where it has been designed and constructed to a recognised National or International Standard.

5.4.3 The cable clench supporting structure is to be adequately stiffened in accordance with the breaking strength of the fastening provided.

5.5 Cable stopping and release arrangements

5.5.1 It is recommended that suitable bow chain stoppers be provided. Where cables pass through stoppers, these stoppers are to be manufactured from ductile material and be designed to minimise the possibility of damage to, or snagging of, the cable. They are to be capable of withstanding without permanent deformation a load equal to 80 per cent of the Rule breaking load of the cable passing over them. The corresponding stresses induced in the supporting structure are not to exceed the allowable values given in Table 5.5.1 Allowable stresses in windlass and chain stopper supporting structure. The capability of the supporting structure to withstand buckling is also to be assessed.

Table 5.5.1 Allowable stresses in windlass and chain stopper supporting structure

Permissible stress

N/mm2
(a) For strength assessment by means of beam theory or grillage analysis (see Note 1):  
Normal stress

Shear stress

Von Mises stress

1,00σ0

0,60σ0

1,00 σ0
(b) For strength assessment by means of finite element analysis (see Note 2):  
Von Mises stress 1,00 σ0
Symbols
σ0= specified minimum yield stress, N/mm2
Note 1. Normal stress is defined as the sum of bending and axial stresses. The shear stress to be considered corresponds to the shear stress acting perpendicular to the normal stress. No stress concentration factors are to be taken into account.
Note 2. For strength assessment by means of finite element analysis, the mesh is to be fine enough to represent the geometry as realistically as possible. The aspect ratios of elements are not to exceed 3. Girders are to be modelled using shell or plane stress elements. Symmetric girder flanges may be modelled by beam or truss elements. The element height of girder webs must not exceed one-third of the web height. In way of small openings in girder webs, the web thickness is to be reduced to an appropriate mean thickness over the web height. Large openings are to be modelled. Stiffeners may be modelled using shell or plane stress elements. The mesh size of stiffeners is to be fine enough to obtain proper bending stress. If flat bars are modelled using shell or plane stress elements, then dummy rod elements are to be modelled at the free edge of the flat bars and the stresses of the dummy elements are to be evaluated. Stresses are to be read from the centre of the individual element. For shell elements the stresses are to be evaluated at the mid plane of the element.

5.6 Cable locker

5.6.1 Adequate storage is to be provided to accommodate the full length of anchor cable.

5.6.2 The chain locker is to be of adequate capacity and depth to provide an easy direct lead of the cables through the chain pipes and to facilitate self-stowing and deployment of the cables. Chain or spurling pipes are to be of suitable size and provided with chafing lips. The port and starboard cables are to be separated by a division in the locker.

5.6.3 The chain locker boundaries are to be watertight up to the mooring deck. However, bulkheads between separate chain lockers, or which form a common boundary of chain lockers, need not be watertight.

5.6.4 Where the means of access to the chain locker is located below the mooring deck, the access cover and its securing arrangement in general are to be in accordance with recognised standards for watertight manholes with bolted covers (e.g. ISO 5894 Ships and marine technology – Manholes with bolted covers). Butterfly nuts and/or hinged bolts are prohibited as the securing mechanism for the access cover.

5.6.5 Chain or spurling pipes through which anchor cables are led shall be provided with permanently attached closing appliances to minimise water ingress. In enclosed mooring decks these are also to be fitted to hawsepipes and be of sufficient strength to resist water jets from bow slamming.

5.6.6 The chain locker is to be provided with adequate drainage facilities, see Vol 2, Pt 7, Ch 2, 3.4 Space above fore, after peaks and machinery spaces 3.4.1.

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