Section 5 Anchor winches and windlasses

5.1.1 Machinery items are to be constructed, installed and tested in accordance with the relevant requirements of Pt 5 Main and Auxiliary Machinery. For electrical and control equipment, see Pt 7, Ch 8, 6 Electrical and control equipment.

5.2.1 Materials are generally to comply with the requirements of Pt 5, Ch 1, 2.2 Materials.

5.2.2 Components have been categorised in this Section as Type P (Primary) and Type S (Secondary) for material selection purposes.

1. Type P: Components where failure would result in the loss of a primary function of the winch or windlass, e.g.:

   Winch drum.

   Windlass cable lifter.

   Reduction gears.

   Shafts.

   Brakes.

   Pawl stoppers.

   Bedplates.

   
   

   NOTE

   Consideration will be given to designating any of the above components as Type S (see below), provided adequate redundancy of operation exists.

2. Type S: Secondary, stressed items, not categorised as Type P, and where failure would not result in the loss of a primary winch function.

5.2.3 Steel materials for Type P or Type S components are generally to comply with the following Chapters and Sections of the Rules for Materials:

1. Plates and bars: Ch 3 Rolled Steel Plates, Strip, Sections and Bars Ch 3, 1 General requirements and Ch 3, 2 Normal strength steels for ship and other structural applications, Ch 3, 3 Higher strength steels for ship and other structural applications or Ch 3, 6 Carbon–manganese and nickel alloy steels for low temperature service, as appropriate.

2. Castings: Ch 4, 1 General requirements and Ch 4, 7 Ferritic steel castings for low temperature service.

3. Forgings: Ch 5, 1 General requirements and Ch 5, 8 Ferritic steel forgings for low temperature service.

Consideration will be given to the acceptance of suitable equivalent National Standards.

5.2.4 Material grades are to be selected to provide the necessary notch toughness. See Table 8.5.1 Material grades for suitable Grades.

5.2.5 The requirements of Pt 7, Ch 8, 5.2 Materials 5.2.3 and Pt 7, Ch 8, 5.2 Materials 5.2.4 apply where the minimum design air temperature is within the range 0°C to minus 15°C. Requirements for design temperatures outside this range will be subject to special consideration.

5.2.6 For components such as gears, shafts and boltings made from rolled or forged bar materials not subject to welding, the material composition and heat treatment, etc. may be submitted for approval as an alternative to the requirements of Table 8.5.1 Material grades.

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

5.2.8 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.

5.2.9 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 castings of the Rules for Materials. This material is not to be used for gear components.

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

5.3.1 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.

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

5.3.3 A residual braking force of at least 50 per cent of the maximum braking force required by Pt 7, Ch 8, 5.5 Winch/Windlass performance 5.5.1 is to be immediately available and automatically applied in the event of a power failure.

5.4.1 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.

5.4.2 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.

5.4.3 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 rated breaking strength of the cable.

5.4.4  See also Pt 7, Ch 8, 6.2 Control stations 6.2.1 and Pt 7, Ch 8, 6.2 Control stations 6.2.2 for stopper control station requirements, and Pt 7, Ch 8, 6.4 Controls 6.4.5 for emergency release of stoppers.

5.5.1 The primary brake is required to hold a static load equal to the minimum 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 that value when a stopper capable of holding 100 per cent of the breaking strength of the line is fitted.

5.5.2 The secondary brake is required to hold a static load equal to 50 per cent of the minimum breaking strength of the anchor line.

5.5.3 The anchor winch or windlass is to have adequate dynamic braking capability. The two brake systems in joint operation are to be capable of fully controlling, without overheating, the anchor lines during:

1. all anchor handling operations;

2. adjustment of anchor line tensions. (This is particularly relevant where the mooring system has been designed and sized, on the basis of active adjustment of anchor lines in extreme conditions, to minimise line tensions).

5.5.4  See also Pt 7, Ch 8, 6.2 Control stations for control of winches, windlasses, stoppers and pawls, and Pt 7, Ch 8, 6.4 Controls 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.

5.5.5 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 breaking strength is recommended.

5.6.1 Design load cases for the winch or windlass assembly and the stopper when fitted are given in Table 8.5.2 Design load cases. The associated maximum allowable stresses are to be based on the factors of safety given in Table 8.5.3 Safety factors for design load cases.

5.7.1 Works tests are to be carried out in the presence of the Surveyor, on at least one of the winch or windlass units out of the total outfit for the vessel. The tests to be carried out are given in Table 8.5.4 Works test. Alternatively, where a prototype winch has been suitably tested, consideration will be given to the acceptance of these results.

5.7.2 The residual braking capability (see Pt 7, Ch 8, 5.5 Winch/Windlass performance 5.5.4) is to be verified.

5.7.3 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. The proposed test programme is to be submitted.

5.8.1 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 7, Ch 8, 5.7 Testing 5.7.1 may not be applicable.