3 Anchoring Equipment

3.1 General

3.1.1 General

Two bower anchors are to be connected to chain cable and stowed in position ready for use.

3.1.2 Design

The anchors are to be of an approved type and satisfy the testing conditions as per the Society’s requirements.

3.2 Ordinary anchors

3.2.1 Anchor mass

The mass per anchor of bower anchors given in Table 1 is for anchors of equal mass. The mass of individual anchors may vary 7% above or below the tabulated value, provided that the combined mass of all anchors is not less than that required for anchors of equal mass.

Anchors are to be of the stockless type. The mass of the head of anchor, including pins and fittings, is not to be less than 60% of the total mass of the anchor.

3.3 High Holding power anchors

3.3.1 General

Where agreed by the owner, consideration will be given to the use of special types of anchors. High Holding Power (HHP), i.e. anchors for which a holding power higher at least twice that of ordinary anchors has been proved according to the applicable requirements of the Society’s Rules for Materials, do not require prior adjustment or special placement on the sea bottom.

3.3.2 HHP anchor mass

Where HHP anchors are used as bower anchors, the mass of each anchor is to be not less than 75% of the mass required for ordinary stockless anchors in Table 1.

3.3.3 Application

High holding power anchors are to be of a design that will ensure that the anchors will take effective hold of the sea bed without undue delay and will remain stable, for holding forces up to those required by the Society, irrespective of the angle or position at which they first settle on the sea bed when dropped from a normal type of hawse pipe. A demonstration of these abilities may be required.

The design approval of high holding power anchors may be given as a general/type approval, and listed in a published document by the Society.

3.4 Chain cables

3.4.1 General

The chain cables are classified as Grade 1, 2 or 3 depending on the type of steel used and its manufacture.

The characteristics of the steel used and the method of manufacture of chain cables are to be approved by the Society for each manufacturer. The material from which chain cables are manufactured and the completed chain cables themselves are to be tested in accordance with the applicable requirements of the Society’s Rules for Materials.

Chain cables which are intended to form part of the equipment are not to be used as check chains when the ship is launched.

3.4.2 Application

The total length of chain required to be carried onboard, as given in Table 1, is to be divided approximately equally between the two anchors.

Where the owner requires equipment for anchoring at depths greater than 82.5 m, it is the owner’s responsibility to specify the appropriate total length of the chain cable required. In such a case, consideration can be given to dividing the chain cable into two unequal lengths.

3.5 Chain lockers and stowed anchors

3.5.1 General

The chain locker is to have adequate capacity and be of a suitable form to provide for the proper stowage of the chain cable, allowing an easy direct lead for the cable into the chain pipes when the cable is fully stowed. Port and starboard cables are to have separate spaces.

The chain locker boundaries and access openings are to be watertight. Provisions are to be made to minimise the probability of the chain locker being flooded in bad weather. Adequate drainage facilities for the chain locker are to be provided.

Chain or spurling pipes are to be of suitable size and provided with chafing lips.

3.5.2 Securing of the inboard ends of chain cables

Provisions are to be made for securing the inboard ends of the chain to the structure. This attachment and its supporting structure are to be able to withstand a force of not less than 15% or more than 30% of the minimum breaking strength of the fitted chain cable.

The fastening of the chain to the ship is to be arranged in such a way that in case of an emergency, when the anchor and chain have to be sacrificed, the chain can be readily released from an accessible position outside the chain locker.

3.5.3 Securing of stowed anchors

Anchor lashings are to be designed to resist a load at least corresponding to twice the anchor mass plus 10 m of cable without exceeding 40% of the yield strength of the lashing material.

3.6 Chain stoppers

3.6.1 General

Chain stoppers are to be provided to secure each chain cable once it is paid out.

3.6.2 Application

Securing arrangements of chain stoppers are to be capable of withstanding a load equal to 80% of the breaking load of the chain cable as required by [3.4.1], without undergoing permanent deformation.

3.7 Windlass

3.7.1 General

A windlass of sufficient power and suitable for the size of chain is to be fitted to the ship in accordance with the requirements of the Society. Where an owner requires equipment significantly in excess of Rule requirements, it is the owner’s responsibility to specify increased windlass power. The windlass is to be capable of heaving in either cable.

3.7.2 Application

The design of the windlass is to be such that access to the chain pipe is adequate to permit the fitting of a cover or seal of sufficient strength over the spurling pipe.

Special consideration will be given to the acceptance of equivalent arrangements that minimise the probability of the chain locker or forecastle being flooded.

3.7.3 Anchor windlass trial

3.8 Hawse pipes

3.8.1 General

Hawse pipes are to be of a suitable size and configuration to ensure adequate clearance and an easy lead of the chain cable from the chain stopper through the ship’s side.

Hawse pipes are to be of sufficient strength.

Their position and slope are to be so arranged as to create an easy lead for the chain cables and efficient housing for the anchors, where the latter are of the retractable type, avoiding damage to the hull during these operations.

For this purpose, chafing lips of suitable form with ample lay-up and radius adequate to the size of the chain cable are to be provided at the shell and deck. The shell plating in way of the hawse pipes is to be reinforced as necessary.

Where hawse pipes are not fitted, alternative arrangements will be specially considered.

3.8.2 Application

Hawse pipes are to be securely attached to thick, doubling or insert plates, by continuous welds.

3.8.3 Stowage and deployment arrangements for anchors

Hawse pipes and anchor pockets are to have full-rounded flanges or rubbing bars in order to minimise the nip on the cables and to minimise the probability of cable links being subjected to high bending stresses. The radius of curvature is to be such that at least three links of chain will bear simultaneously on the rounded parts of the upper and lower ends of the hawse pipes in those areas where the chain cable is supported during paying out and hoisting and when the ship is at anchor.

On ships provided with a bulbous bow, where it is not possible to obtain a suitable clearance between shell plating and the anchors during anchor handling, local reinforcements of the bulbous bow are to be provided in the form of increased shell plate thickness.

3.9 Towlines and mooring line

3.9.1 General

Mooring lines and towlines are not required as a condition of Classification.

Side projected area including that of deck cargoes as given by the loading manual is to be taken into account for selection of towing/mooring lines.