Section 10 Anchoring equipment in deep and unsheltered water
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 10 Anchoring equipment in deep and unsheltered water

Section 10 Anchoring equipment in deep and unsheltered water

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

10.1 General

10.1.1 It is recommended that the equipment requirements specified in this Section are complied with if the vessel intends to anchor in deep and unsheltered waters. Where a ship’s anchoring equipment complies with the requirements of this Section, the ship will be eligible to be assigned the notation DWA.

10.1.2 The equipment specified is for ships intended to anchor in water with depth up to 120 m, current with speed up to 1,54 m/s, wind with speed up to 14 m/s and waves with significant height of up to 3 m. The scope of chain cable, being the ratio between the length of chain paid out and water depth, is assumed to be not less than 3 to 4. These requirements are applicable only to ships with a Rule length LR of not less than 135 m.

10.1.3 The requirements specified in other Sections of this Chapter need to be complied with unless alternative requirements are provided.

10.2 Anchor and chain cable

10.2.1 Anchors and chain cables to be in accordance with Table 5.10.1 Anchoring equipment for ships in unsheltered water with depth up to 120 m and based on the Equipment Number EN1 obtained from the following equation.
where
a =
b =
LR = Rule length, in metres, see Vol 1, Pt 3, Ch 1, 5.2 Principal particulars 5.2.2
EN = Equipment Number calculated in accordance with Vol 1, Pt 3, Ch 5, 2.1 Equipment Number calculation

10.2.2 The bower anchors are to be connected to their chain cables and positioned on board ready for use.

10.2.3 Anchors are to be of the stockless High Holding Power (HHP) type. The mass of the head of a stockless anchor, including pins and fittings, is to be not less than 60 per cent of the total mass of the anchor.

10.2.4 The mass, per anchor, of bower anchors given in Table 5.10.1 Anchoring equipment for ships in unsheltered water with depth up to 120 m is for anchors of equal mass. The mass of individual anchors may vary to 7 per cent of the tabular mass, but the total mass of anchors is not be less than that specified for anchors of equal mass.

10.2.5 Bower anchors are to be associated with stud link chain cables of special (U2) or extra special (U3) quality. The total length of chain cable, as given in Table 5.10.1 Anchoring equipment for ships in unsheltered water with depth up to 120 m is to be approximately divided between the two bower anchors.

10.3 Anchor windlass and chain stopper

10.3.1 Notwithstanding the requirements according to Vol 1, Pt 3, Ch 5, 8.4 Windlass design 8.4.1, the windlass unit prime mover is to be able to supply for at least 30 minutes a continuous duty pull Zcont, in N, given by:
Zcont = 35 d2 + 13,4 mA
10.3.2 The windlass is to have sufficient power to exert, over a period of at least two minutes, a pull equal to the greater of:
  1. short term pull:

    1,5 times the continuous duty pull as defined in Vol 1, Pt 3, Ch 5, 10.3 Anchor windlass and chain stopper 10.3.1

  2. anchor breakout pull:

10.3.3 The capacity of the windlass brake is to be sufficient to stop the anchor and chain cable when paying out the chain cable. 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 is to be applied instead.

10.3.4 In addition to the requirements of Vol 1, Pt 3, Ch 5, 8.11 On-board testing 8.11.2, as far as practicable, for testing purposes the speed of the chain cable during hoisting of the anchor and cable should be measured over 37,5 m of chain cable and initially with at least 120 m of chain with the anchor submerged and hanging free. The mean speed of the chain cable during hoisting of the anchor from the depth of 120 m to the depth of 82,5 m should be at least 4,5 /min.

10.3.5 The chain cable stopper, if fitted, along with its attachments is to be designed to withstand, without any permanent deformation, 80 per cent of the specified minimum breaking strength of the chain cable.

Table 5.10.1 Anchoring equipment for ships in unsheltered water with depth up to 120 m

Equipment Number

EN1

 High holding power stockless bower anchors Stud link chain cable for bower anchors
Equal to or greater than Less than Number

Mass per anchor (mA)

(kg)

Length

(m)

 Min. diameter (d)

Special quality

(Grade U2)

(mm)

Extra special quality

(Grade U3)

(mm)
1790 2 14150 1017,5 105 84
1790 1930 2 14400 990 105 84
1930 2080 2 14800 990 105 84
2080 2230 2 15200 990 105 84
2230 2380 2 15600 990 105 84
2380 2530 2 16000 990 105 84
2530 2700 2 16300 990 105 84
2700 2870 2 16700 990 105 84
2870 3040 2 17000 990 105 84
3040 3210 2 17600 990 105 84
3210 3400 2 18000 990 105 84
3400 3600 2 18300 990 106 84
3600 3800 2 19000 990 107 85
3800 4000 2 19700 962,5 108 87
4000 4200 2 20300 962,5 111 90
4200 4400 2 21100 962,5 114 92
4400 4600 2 22000 962,5 117 95
4600 4800 2 22900 962,5 119 97
4800 5000 2 23500 962,5 122 99
5000 5200 2 24000 935 125 102
5200 5500 2 24500 907,5 130 105
5500 5800 2 25000 907,5 133 107
5800 6100 2 25500 880 137 111
6100 6500 2 25700 880 140 113
6500 6900 2 26000 852,5 143 115
6900 7400 2 26500 852,5 147 118
7400 7900 2 27000 825 152 121
7900 8400 2 27500 825 154 123
8400 8900 2 28000 797,5 158 127
8900 9400 2 28900 770 162 132
9400 10000 2 29400 770 - 135
10000 10700 2 29900 770 - 139
10700 11500 2 30600 770 - 143
11500 12400 2 31500 770 - 147
12400 13400 2 33200 770 - 152
13400 14600 2 35000 770 - 157
14600 2 38000 770 - 162
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