Section 8 Anchor windlass design and testing

8.1.1 A windlass used for handling anchors, suitable for the size of chain cable required by Pt 3, Ch 13, 7 Equipment and complying with the following criteria is to be fitted. Where Owners require equipment significantly in excess of Rule requirements, it is their responsibility to specify increased windlass power.

8.1.2 The design, construction and testing of windlasses are to conform with a relevant National or International Standard or code of practice acceptable to LR. To be considered acceptable, the standard, or code of practice, is to specify criteria for evaluation of stresses, performance and testing.

8.1.3 Operation and maintenance procedures for the anchor windlass are to be incorporated in the vessel operations manual.

8.3.1 Materials used in the construction of torque-transmitting and load-bearing parts of windlasses are to comply with LR's Rules for the Manufacture, Testing and Certification of Materials, July 2022 or an appropriate National or International Standard acceptable to LR, provided that the Standard gives reasonable equivalence to the requirements of LR. The proposed materials are to be indicated in the construction plans and are to be approved in connection with the design. All such materials are to be certified by the material manufacturers and are to be traceable to the manufacturers’ certificates.

8.3.2 Weld joint designs are to be shown in the submitted construction plans and are to be appraised in association with the approval of the windlass design in accordance with an appropriate National or International Standard acceptable to LR. .

8.3.3 Welding procedures, welding consumables and welders are to comply with the LR Rules for the Manufacture, Testing and Certification of Materials, July 2022 or an appropriate National or International Standard acceptable to LR.

8.3.4 The degree of non-destructive examination of welds and post-weld heat treatment, if any, are to be specified and submitted for consideration.

8.4.1 In addition to the requirements of the National or International Standard or code of practice acceptable to LR (see Pt 3, Ch 13, 8.1 General 8.1.2) the following performance requirements are to be complied with:

1. Holding Loads: Calculations are to be made to show that, in the holding condition (single anchor, brake fully applied and chain cable lifter declutched) and under a load equal to 80 per cent of the specified minimum breaking strength of the chain cable, the maximum stress in each load bearing component will not exceed the maximum permissible yield. For installations fitted with a chain cable stopper, 45 per cent of the specified minimum breaking strength of the chain cable may instead be used for the calculation.
2. Inertia Loads: The design of the drive train, including prime mover, reduction gears, bearings, clutches, shafts, cable lifter and bolting is to consider the dynamic effects of sudden stopping and starting of the prime mover or chain cable, so as to limit inertial load.
3. Continuous Duty Pull: The windlass is to have sufficient power to exert a continuous duty pull , Z_cont1, over a period of 30 minutes corresponding to the grade and diameter, d_c, of the chain cables as follows:
   1. for specified design anchorage depths up to 82,5 m when using ordinary stockless anchors: :

      Chain cable grade	Zcont1 (N)
      U1	37,5d c 2
      U2	42,5d c 2
      U3	47,5d c 2

   2. for specified design anchorage depths greater than 82,5 m a continuous duty pull Z_cont2 is:
      
      where

      dc	=	is the chain diameter, in mm
      Da	=	is the specified design anchorage depth, in metres

   The anchor masses are assumed to be the masses as given in Table 13.7.2 Equipment - Bower anchors and chain cables. The value of Z_cont is based on the hoisting of one anchor at a time, and assumes that the effects of buoyancy and hawse pipe efficiency (assumed to be 70 per cent) have been accounted for. In general, stresses in each torque-transmitting component are not to exceed 40 per cent of yield strength (or 0,2 per cent proof stress) of the material under these loading conditions.

4. Overload Capability: The windlass prime mover is to be able to provide, for a period of at least two minutes, the necessary temporary overload capacity for breaking out the anchor. This temporary overload capacity is to be a pull equal to the greater of:

   1. short term pull:

      1,5 times the continuous duty pull as defined in Pt 3, Ch 13, 8.4 Windlass design 8.4.1.(c), or

   2. anchor breakout pull:

      
      where:

      Lc	=	is the total length of chain cable on board, in metres, as given by Table 13.7.2 Equipment - Bower anchors and chain cables
      Wa	=	is the mass of bower anchor (kg) as given in Table 13.7.2 Equipment - Bower anchors and chain cables.

   Note The speed in this period may be lower than normal.
5. Hoisting Speed: The mean speed of the chain cable during hoisting of the anchor and cable is to be 0,15 m/s.
6. Brake Capacity: The capacity of the windlass brake is to be sufficient to stop the anchor and chain cable when paying out the chain cable in a controlled manner. Where a chain cable stopper is not fitted, the brake is to produce a torque capable of withstanding a pull equal to 80 per cent of the specified minimum breaking strength of the chain cable without any permanent deformation of strength members and without brake slip. Where a chain cable stopper is fitted, 45 per cent of the breaking strength may instead be applied. The following simplified formula is to be used to calculate the required brake capacity:

   K _b d _c ² (44 − 0,08d _c) N

   where K _b is given in Table 13.8.1 Values of K_b .

8.4.2 As an alternative to conducting the engineering analyses required by Pt 3, Ch 13, 8.4 Windlass design 8.4.1, approval of the windlass mechanical design can be based on a type test, in which case the testing procedure is to be submitted for consideration.

8.4.3 Calculations for torque transmitting components are to be based on 1500 hours of operation with a nominal load spectrum factor of K_m = 1,0. Alternatively unlimited hours with K_m = 0,8 can be applied.

8.4.4 The following criteria are to be used for gearing design:

1. Torque is to be based on the performance criteria specified in Pt 3, Ch 13, 8.4 Windlass design 8.4.1.

2. The use of an equivalent torque, T _eq, for dynamic strength calculations is acceptable but the derivation is to be submitted to LR for consideration.

3. The application factor for dynamic strength calculation, K _A, is to be 1,15.

4. Calculations are to be based on 1500 hours of operation.

5. The static torque is to be 1,5 x T _n where T _n is the nominal torque.

6. The minimum factors of safety for load capacity of spur and helical gears, as derived using ISO 6336 or a relevant National or International standard acceptable to LR, are to be 1,5 for bending stress and 0,6 for contact stress.

Gears intended to transmit power greater than 100 kW are to be certified by LR, and the gears are to meet the requirements of Pt 5, Ch 5 Gearing.

8.5.1 Hydraulic systems, where employed for driving windlasses, are to comply with the requirements of Pt 5, Ch 14, 9 Hydraulic systems.

8.6.1 Electric motors are to meet the requirements of Pt 6, Ch 2, 9 Rotating machines. Motors exposed to weather are to have enclosures suitable for their location, see also Pt 6, Ch 2, 1.11 Location and construction 1.11.1.

8.6.2 Motor branch circuits are to be protected in accordance with the applicable Rules, and cable sizing is to be in accordance with the requirements of the Pt 6, Ch 2, 11 Electric cables, optical fibre cables and busbar trunking systems (busways).

8.7.1 All control devices are to be capable of being controlled from readily accessible positions and protected against unintentional operation.

8.7.2 The maximum travel of the levers is not to exceed 600 mm if movable in one direction only, or 300 mm to either side from a central position if movable in both directions. They are to move toward the right when hauling and toward the left when paying out. Alternatively, they are to move backward when hauling and forward when paying out.

8.7.3 Wherever practical, the lever is to move in the direction of the intended movement.

8.7.4 For lever-operated brakes, the brake is to engage when the lever is pulled and disengage when the lever is pushed. The physical effort on the brake for the operator is not to exceed 160 N.

8.7.5 For pedal-operated brakes the maximum travel is not to exceed 250 mm and the physical effort for the operator is not to exceed 320 N.

8.7.6 The handwheel or crankhandle is to actuate the brake when turned clockwise and release it when turned counterclockwise. The physical effort for the operator is not to exceed 250 N for speed regulation and 500 N at any moment.

8.7.7 When not provided with automatic sequential control, separate push-buttons are to be provided for each direction of operation.

8.7.8 The push-buttons are to actuate the machinery when depressed and stop and effectively brake the machinery when released.

8.7.9 The above mentioned individual push-buttons may be replaced by two ‘start’ and ‘stop’ push-buttons.

8.7.10 Control systems, whether electric, pneumatic or hydraulic, are to comply with the general requirements of Pt 6, Ch 1, 2 Essential features for control, alarm, monitoring and safety systems .

8.8.1 Where applicable, moving parts of windlass machinery are to be provided with suitable railings and/or guards to prevent injury to personnel.

8.8.2 Protection is to be provided for preventing persons from coming into contact with surfaces having temperatures over 50°C.

8.8.3 Steel surfaces not protected by lubricant are to be protected by a coating in accordance with the requirements of a relevant National or International Standard acceptable to LR.

8.8.4 For arrangements of power transmission systems and relief requirements see Pt 5, Ch 14, 9.1 General.

8.8.5 Electrical cables installed in exposed locations on open deck are to be provided with effective mechanical protection.

8.8.6 Means are to be provided to contain potential debris resulting from severe damage of the prime mover due to over-speed in the event of uncontrolled rendering of the cable, particularly when an axial piston type hydraulic motor forms the prime mover.

8.8.7 An arrangement to release the anchor and chain in the event of windlass power failure is to be provided. Windlasses are to be fitted with couplings which are capable of disengaging between the cable lifter and the drive shaft. Hydraulically or electrically operated couplings are to be capable of being disengaged manually.

8.8.8 The design of the windlass is to be such that the following requirements or equivalent arrangements will minimise the probability of the chain locker or forecastle being flooded in bad weather:

1. a weathertight connection can be made between the windlass bedplate, or its equivalent, and the upper end of the chain pipe by means of a cover or seal, and

2. access to the chain pipe is adequate to permit the fitting of a cover or seal, of sufficient strength and proper design, over the chain pipe while the ship is at sea.

8.9.1 Windlasses are to be inspected during fabrication at the manufacturers’ facilities by a Surveyor for conformance with the approved plans. Acceptance tests, as specified in the specified Standard (see Pt 3, Ch 13, 8.1 General 8.1.2), are to be witnessed by the Surveyor and include the following tests, as a minimum:

1. No-load test. The windlass is to be run without load at nominal speed in each direction for a total of 30 minutes. If the windlass is provided with a gear change, an additional run in each direction for 5 minutes at each gear change is required.
2. Load test. The windlass is to be tested to verify that the continuous duty pull, overload capacity and hoisting speed as specified in Pt 3, Ch 13, 8.4 Windlass design 8.4.1 can be achieved.

   Where the manufacturer’s works does not have adequate facilities, these tests, including the adjustment of the overload protection, can be carried out on board ship. In these cases, functional testing in the manufacturer’s works is to be performed under no-load conditions.

3. Brake capacity test. The holding power of the brake is to be verified through testing if not verified by calculation.

8.9.2 Windlass performance characteristics specified in Pt 3, Ch 13, 8.9 Shop inspection and testing 8.9.1 are based on the following assumptions:

1. one cable lifter only is connected to the drive shaft;

2. continuous duty and short term pulls are measured at the cable lifter;

3. hawse pipe efficiency assumed to be 70 per cent.

8.10.1 Each windlass is to be tested under working conditions after installation on board to demonstrate satisfactory operation. Each unit is to be independently tested for braking, clutch functioning, lowering and hoisting of the chain cable and anchor, proper riding of the chain over the cable lifter, proper transit of the chain through the hawse pipe and the chain pipe, and effecting proper stowage of the chain and the anchor. It is to be confirmed that anchors properly seat in the stored position and that chain stoppers function as designed, if fitted. The braking capacity is to be tested by intermittently paying out and holding the chain cable by means of the application of the brake.

8.10.2 During trials on board ship, the windlass is to be shown to be capable of:

1. For all specified design anchorage depths, the mean hoisting speed, as specified in Pt 3, Ch 13, 8.4 Windlass design 8.4.1.(e) is to be measured and verified. For testing purposes, the speed is to be measured over two shots of chain cable and initially with at least three shots of chain (82,5 m or 45 fathoms in length) and the anchor submerged and hanging free.
2. For specified design anchorage depths greater than 82,5 m: in addition to Pt 3, Ch 13, 8.10 On-board testing 8.10.2.(a), raising the anchor from the specified design anchorage depth to a depth of 82,5 m at a mean speed of 3 m/min.

Following trials, the ship will be eligible to be assigned a descriptive note specified design anchorage depth . . . metres, which will be entered in column 6 of the Register Book.

8.10.3 Load testing is to be carried out if this was not previously completed as required by Pt 3, Ch 13, 8.9 Shop inspection and testing 8.9.1.(b).

8.10.4 Where the depth of water in the trial area is inadequate, suitable equivalent simulating conditions will be considered as an alternative.

8.11.1 The windlass is to be permanently marked with the following information:

1. The size designation of the windlass (e.g. 100/3/45, where 100 is the nominal diameter of the chain cable in mm, 3 is the numeral in the chain cable steel grade U3, and 45 refers to the holding load expressed as a percentage of the chain cable breaking load).
2. Maximum anchorage depth, in metres.

8.12.1 The windlass or winch is to be efficiently bedded and secured to the deck. The thickness of the deck in way of the windlass or winch is to be increased and the supporting structure for the anchor windlass is to be examined for the brake holding loads specified by Pt 3, Ch 13, 8.4 Windlass design. The allowable stresses specified in Table 13.8.2 Allowable stresses in windlass and chain stopper supporting structure are to be used to derive the net scantlings of the supporting structure. The capability of the supporting structure to withstand buckling is also to be assessed. A corrosion addition of 2 mm is to be added to the net thickness derived. The structural design integrity of the bedplate is the responsibility of the Shipbuilder and windlass or winch manufacturer.

8.12.2 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 allowable stresses specified in Table 13.8.2 Allowable stresses in windlass and chain stopper supporting structure are to be used to derive the net scantlings of the supporting structure. The capability of the supporting structure to withstand buckling is also to be assessed. A corrosion addition of 2 mm is to be added to the net thickness derived.

8.12.3 Hawse pipes and anchor pockets are to be of ample thickness and of a suitable size and form to house the anchors efficiently, preventing, as much as practicable, slackening of the cable or movements of the anchor being caused by wave action. The shell plating and framing in way of the hawse pipes are to be reinforced as necessary. Reinforcing is also to be arranged in way of those parts of bulbous bows liable to be damaged by anchors or cables. Substantial chafing lips are to be provided at shell and deck. These are to have sufficiently large, radiused faces to minimise the probability of cable links being subjected to high bending stresses. Alternatively, roller fairleads of suitable design may be fitted. Where unpocketed rollers are used, it is recommended that the roller diameter be not less than eleven times the chain diameter. Where hawse pipes are not fitted, alternative arrangements will be specially considered.

8.12.4 The chain locker is to be of a capacity and depth adequate to provide an easy direct lead for the cable into the chain pipes, when the cable is fully stowed. 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.

8.12.5 Where means of access is provided to the chain locker it is to be closed by a substantial cover and secured by closely spaced bolts. Where a means of access to spurling pipes or cable lockers is located below the weather deck, the access cover and its securing arrangements are to be in accordance with ISO 5894-1999, or an equivalent National Standard acceptable to LR, recognised standards or equivalent for watertight manhole covers. Butterfly nuts and/or hinged bolts are prohibited as the securing mechanism for the access cover.

8.12.6 Chain lockers and spurling pipes are to be watertight up to the exposed weather deck and the space is to be efficiently drained. However, bulkheads between separate chain lockers, or which form a common boundary of chain lockers, need not be watertight.

8.12.7 Spurling pipes are to be provided with permanently attached closing appliances to minimise water ingress. Examples of acceptable arrangements are:

1. steel plates with cutouts to accommodate chain links, or

2. canvas hoods with a lashing arrangement that maintains the cover in the secured position.

8.12.8 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.

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

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

8.12.11 Satisfactory arrangements are to be made for the stowage and working of the stream anchor, if provided.

8.12.12 On dredging and reclamation craft the following are to be complied with:

1. On unpowered ships, the windlass may be hand operated.

2. On split type vessels, the arrangements are to be such that jamming of the anchor cable during opening and closing operations of the hull will not occur.

8.12.13 When wire rope instead of chain is used for the anchor cable, it is to be stored on a suitably designed drum or reel. Fairleads intended for use with wire rope cable are to be designed to minimise wear and to avoid kinking or other damage occurring to the rope. Fairleads should, in general, be fitted with rollers having a diameter not less than eleven times the diameter of the anchor cable or as specified/ recommended by the rope manufacturer.

8.13.1 Windlasses located on the exposed deck over the forward 0,25L of the rule length, of ships of sea-going service of length 80 m or more, where the height of the exposed deck in way of the item is less than 0,1L or 22 m above the summer load waterline, whichever is the lesser, are to comply with the following requirements. Where mooring winches are integral with the anchor windlass, they are to be considered as part of the windlass.

8.13.2 The following pressures and associated areas are to be applied, see Figure 13.8.1 Windlass loading:

• 200 kN/m² normal to the shaft axis and away from the forward perpendicular, over the projected area in this direction;
• 150 kN/m² parallel to the shaft axis and acting both inboard and outboard separately, over the multiple of f times the projected area in this direction;

Note P_y is to be examined from both inboard and outboard directions separately, see Pt 3, Ch 13, 8.13 Structural requirements for windlasses on exposed fore decks 8.13.2. The sign convention for y_i is reversed when P_Y is from the opposite direction as shown.

Figure 13.8.1 Windlass loading

8.13.3 Forces in the bolts, chocks and stoppers securing the windlass to the deck are to be calculated. The windlass is supported by N bolt groups, each containing one or more bolts, see Figure 13.8.2 Direction of forces and weight.

Figure 13.8.2 Direction of forces and weight

8.13.4 The axial force R _i in bolt group (or bolt) i, positive in tension, may be calculated from:

R xi

=

P x h x i A i/x in kN

R yi

=

P y h y i A i/y in kN, and

where

P x	=	force acting normal to the shaft axis, in kN
P y	=	force acting parallel to the shaft axis, either inboard or outboard whichever gives the greater force in bolt group i, in kN
h	=	shaft height above the windlass mounting, in cm
x i, y i	=	x and y coordinates of bolt group i from the centroid of all N bolt groups, positive in the direction opposite to that of the applied force, in cm
A i	=	cross sectional area of all bolts in group i, in cm2
x	=	Σ A i x i 2 for N bolt groups, in cm4
y	=	Σ A i y i 2 for N bolt groups, in cm4
R si	=	static reaction at bolt group i, due to weight of windlass, in kN.

8.13.5 Shear forces F _xi, F _yi applied to the bolt group i, and the resultant combined force F _i may be calculated from:

F i

=

8.13.6 Tensile axial stresses in the individual bolts in each bolt group i are to be calculated. The horizontal forces F _xi and F _yi are normally to be reacted by shear chocks. Where ‘fitted’ bolts are designed to support these shear forces in one or both directions, the von Mises equivalent stresses in the individual bolts are to be calculated, and compared to the stress under proof load. Where pourable resins are incorporated in the holding down arrangements, due account is to be taken in the calculations.

8.13.7 The safety factor against bolt proof strength is to be not less than 2,0.

8.13.8 Bolts are to be of lSO 898/1 material Grade 8.8, 10.9 or 12.9 or equivalent and are to be pretensioned by controlled means to 70 to 90 per cent of their yield stress. Pretensioning is to be in accordance with the manufacturer’s instructions and, in general, pretensioning by bolt torqueing up to bolt size M30 may be used. Beyond this, pretensioning is to be carried out by an hydraulic tensioning device and the elongation of the bolts measured to determine pre-load. Where resin chocks are proposed plans and calculations are to be submitted for consideration.

8.13.9 The windlass is to be efficiently bedded and secured to the deck. The thickness of the deck in way of the windlass is to be increased. Adequate stiffening of the deck in way of the windlass is to be provided. The scantlings of the supporting structure and deck are to be determined by additional calculations applying the weight of the windlass combined with the resultant force on the seat due to the application of the following design loads:

• P _x (as defined in Pt 3, Ch 13, 8.13 Structural requirements for windlasses on exposed fore decks 8.13.4);
• P _y;
• P _x and P _y combined;

The allowable stresses specified in Table 13.8.2 Allowable stresses in windlass and chain stopper supporting structure are to be used to derive the net scantlings of the supporting structure. The capability of the supporting structure to withstand buckling is also to be assessed. A corrosion addition of 2 mm is to be added to the net thickness derived.

8.13.10 The axial tensile and compressive forces in Pt 3, Ch 13, 8.13 Structural requirements for windlasses on exposed fore decks 8.13.4 and the lateral forces in Pt 3, Ch 13, 8.13 Structural requirements for windlasses on exposed fore decks 8.13.5 are also to be considered in the design of the supporting structure.