Section 11 Anchor winches and windlasses

11.1.1 This Section applies to winches and windlasses designed actively to control anchor line tensions in-service, or to release anchor lines in an emergency.

11.1.2 Special consideration will be given to requirements for winches and windlasses for passive mooring systems, or permanent mooring systems.

11.1.3 Machinery items are to be constructed to recognised design Codes and Standards. The relevant requirements of Pt 5 MAIN AND AUXILIARY MACHINERYmay be used as guidance for small and simple equipment, but, special analysis techniques such as finite element methods (or equivalent) are considered to be more appropriate.

11.1.4 Machinery items are to be installed and tested in accordance with the relevant requirements of Pt 5 MAIN AND AUXILIARY MACHINERY. For electrical and control equipment, see Pt 3, Ch 10, 12 Electrical and control equipment.

11.1.5 Along this Section the maximum break load refers to the maximum break strength (as new and based on expected maximum break strength plus two standard deviations) of the main component (steel wire rope, chain or fibre rope) directly acting on or closest in the load path to the structure under consideration and is generally not to be taken lower than 110% of the nominal minimum break strength of the component.

11.2.1 Materials are to comply with the Rules for Materials. Alternatively, materials which comply with national or proprietary specifications may be accepted, provided that these specifications give reasonable equivalence to the requirements of the Rules for Materials, or are approved for a specific application. Generally, survey and certification are to be carried out in accordance with the requirements of the Rules for Materials.

11.2.2 For the selection of material grades, individual components of anchor winches and windlasses are to be categorised as primary or secondary.

11.2.3 Components where the failure would result in the loss of a primary function of the winch or windlass are considered to be ‘primary components’, see also Pt 3, Ch 10, 11.2 Materials.

11.2.4 All other components where the failure would not result in the loss of a primary function of the winch or windlass are to be categorised as ‘secondary components’.

11.2.5 Primary components which are designed with an adequate degree of redundancy in their operation will be specially considered and may be categorised as secondary.

11.2.6 Material grades for all components are in general related to the thickness of the material, the structural category and the minimum design air temperature and are to be selected to provide adequate notch toughness.

11.2.7 Material grades for welded plate components are in general to comply withPt 4, Ch 2, 4 Steel grades For thicker plates and/or lower design temperature the steel grades will be specially considered.

11.2.8 Material grades for components which are not subject to welding will be specially considered.

11.2.9 Castings and forgings are to comply with Ch 4 Steel Castingsand Ch 5 Steel Forgings of the Rules for Materials respectively and the requirements for notch toughness in relation to the design air temperature will be specially considered.

11.2.10 Non-ductile materials are not to be used for torque transmitting items or for those elements subject to tensile/bending stresses.

11.2.11 Spheroid graphite iron castings are to comply with Ch 7, 3 Spheroidal or nodular graphite iron castings of the Rules for Materials, Grades 370/17 or 400/12, or to an equivalent National Standard.

11.2.12 The use of grey iron castings will be subject to special consideration. Where approved, they are to comply with the requirements of Ch 7, 2 Grey iron castingsof the Rules for Materials. This material is not to be used for gear components.

11.2.13 Brake lining materials are to be compatible with operating environmental conditions.

11.3.1 Each anchor winch or windlass is required to have one primary braking system and one secondary braking system. The two systems are to operate independently. The requirements of Pt 3, Ch 10, 11.5 Winch/windlass performance are to be complied with.

11.3.2 The braking action of the motor unit may be used for secondary braking purposes where the design is suitable.

11.3.3 A residual braking force of at least 50 per cent of the maximum braking force required by Pt 3, Ch 10, 11.5 Winch/windlass performance is to be immediately available and automatically applied in the event of a power failure.

11.4.1 If the winch motor is to be used as a secondary brake then a stopper is to be provided to take the anchor line load during maintenance of the primary brake.

11.4.2 The stopper may be one of two different types: a pawl stopper fitted at the cable lifter/drum shaft, or a stopper acting directly on the anchor line.

11.4.3 Where the stopper acts directly on the cable, its design is to be such that the cable will not be damaged by the stopper at a load equivalent to the nominal minimum breaking strength of the cable (as new).

11.4.4  See also Pt 3, Ch 10, 12.4 Controls of winch and windlass systems 12.4.11 and Pt 3, Ch 10, 12.4 Controls of winch and windlass systems 12.4.12 , for stopper control station requirements, and Pt 3, Ch 10, 12.4 Controls of winch and windlass systems 12.4.6 , for emergency release of stoppers.

11.5.1 The primary brake is required to hold a static load equal to the maximum break strength of the anchor line (at the intended outer working layer of wire rope on storage drum winches). The static load capacity of the primary brake can be reduced to 80 per cent of the nominal minimum break load of the mooring line (as new) when a stopper, capable of holding maximum breaking strength of the line, is fitted.

11.5.2 The secondary brake is required to hold a static load equal to 50 per cent of the nominal minimum breaking strength of the anchor line (as new).

11.5.3 For passive or permanent positional mooring systems the primary brake is required to hold a static load equal to 150 per cent of the winch/windlass capacity, when isolated from operational/survival mooring line loads using a stopper. A secondary brake is not required in this case.

11.5.5  See also Pt 3, Ch 10, 12.4 Controls of winch and windlass systems 12.4.1 for control of winches, windlasses, stoppers and pawls, for brake fail-safe requirements and standby power for operation of brakes and release of stoppers in the event of a failure of normal power supply.

11.5.6 Means are to be provided to enable the anchor lines to be released from the unit after loss of main power.

11.5.7 On Offshore Mobile Units, the pulling force of the winches or windlasses is to be sufficient to carry out anchor pre-loading on location, to the necessary level. A minimum low-speed pull equal to 40 per cent of the anchor line nominal minimum breaking strength is recommended.

11.6.1 Design load cases for the winch or windlass assembly and the stopper, when fitted, are given in Pt 3, Ch 10, 11.6 Strength 11.6.1 . The associated maximum allowable stresses are to be based on the factors of safety given in Pt 3, Ch 10, 11.7 Testing 11.7.2 .

11.7.1 Tests are to be carried out at the manufacturer’s works in the presence of the Surveyor, on at least one of the winches or windlasses out of the total outfit for the unit. The tests to be carried out are given in Pt 3, Ch 10, 11.7 Testing 11.7.2 . Alternatively, where a prototype winch has been suitably tested, consideration will be given to the acceptance of these results.

11.7.2 The residual braking capability is to be verified in accordance with Pt 3, Ch 10, 11.5 Winch/windlass performance.

Table 10.11.2 Load case factors of safety

Stress	Load case
	1 and 2	3
	Factor of safety
Shear	1,89	2,5
Tension, compression, bending	1,25	1,67
Combined	1,11	1,43
NOTES
1. Factors of safety relate to tensile yield stress.
2. Combined stress = Where σX and σY 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.

11.7.3 Each winch or windlass is to be tested on board the vessel in the presence of the Surveyor, to demonstrate that all main aspects including dynamic brakes function satisfactorily.

A static overload test to 125% of the winch´s Nominal Load (defined as the chain or rope tension that the winch is able to maintain continuously when hauling at nominal speed, measured either at the cable-lifter exit, or at the rope exit of the first layer in the case of a wire-drum shall be considered in addition to functional testing carried out on board.. Further guidance on testing to be carried out can be gained from BS 7464:1991/ISO 9089.

The proposed test programme is to be submitted.

11.7.4 Mooring winches and windlasses are to be regularly tested during service as part of the inspection maintenance and repair plan. Note that winches used in support of inspection, maintenance and repair plan (e.g. to shift chain links in the stopper during inspections) should be maintained as well as winches used in support of mooring line failure or loss of station keeping capability. The failure response procedure is to be kept in good working condition and regularly tested.

11.8.1 Winches or windlasses may be Type Approved in accordance with LR’s Type Approval Scheme. Where this Type Approval is obtained, the requirements of Pt 3, Ch 10, 11.7 Testing may not be applicable.