Section
1 Anchoring equipment
1.1 General
1.1.1 For self-propelled units to be assigned the figure (1) in the
character of Classification, the anchoring equipment, i.e. anchors, cables, windlass
and winches, etc. necessary for the unit during ocean voyages or location moves, is
to be as required by this Section. The Regulations governing the assignment of the
figure (1) for equipment are given in Pt 1, Ch 2, 2 Definitions, character of classification and class notations.
1.1.2 When the equipment fitted to the unit is designed primarily as
positional mooring equipment, consideration will be given to accepting the proposed
equipment as equivalent to the Rule requirements but only if the arrangements are
such that it can be efficiently used as anchoring equipment. See also
Pt 1, Ch 2, 2.3 Character Symbols and Pt 3, Ch 10 Positional Mooring Systems.
1.1.3 Where the Classification Committee has agreed that anchoring and mooring
equipment need not be fitted in view of the particular service of the unit, the
character letter N will be assigned, see also
Pt 1, Ch 2, 2.2 Modes of operation.
1.2 Equipment number
1.2.1 The requirement for anchors, cables, wires and ropes is to be based on
an Equipment Number calculated as follows:
Equipment Number = ![](svgobject/847B-45FB-A801-5A94F0FB9E80.xml_d9078620e152.png)
where
![](svgobject/847B-45FB-A801-5A94F0FB9E80.xml_d9078620e271.png) |
= |
moulded displacement in transit condition, in tonnes |
![](svgobject/847B-45FB-A801-5A94F0FB9E80.xml_d9078620e298.png) |
= |
projected area perpendicular to wind direction when at anchor,
in m2
|
![](svgobject/847B-45FB-A801-5A94F0FB9E80.xml_d9078620e343.png) |
= |
projected area parallel to wind direction when at anchor, in
m2 |
In calculating the areas ![](svgobject/847B-45FB-A801-5A94F0FB9E80.xml_d9078620e383.png) and ![](svgobject/847B-45FB-A801-5A94F0FB9E80.xml_d9078620e412.png) :
- Masking effect can be taken into account for columns;
- Open trusswork of derricks, booms and towers, etc. may be
approximated by taking 30 per cent of the block area of each side, i.e. 60
per cent of the projected area of one side for double sided trusswork.
- When calculating projected areas, account is to be taken of
topside process facilities. Special consideration will be given to structure
extending outside of the Rule length, L.
1.3 Determination of equipment
1.4 Anchors
1.4.1 Two anchors are to be fitted and arranged so that they may be readily
dropped should an emergency occur.
1.4.2 The mass of each anchor is to be as given in Table 9.1.1 Equipment - Anchors and
chain cablesexcept that one anchor may
weigh seven per cent less than the Table weight so long as the total weight of the
two anchors attached to the cables is not less than twice the tabular weight for one
anchor.
1.4.3 Anchors are to be of approved design. The design of all anchor heads is
to be such as to minimise stress concentrations, and in particular, the radii on all
parts of cast anchor heads are to be as large as possible, especially where there is
a considerable change of section.
1.4.4 Positional mooring anchors of the type which are generally similar to
conventional marine anchors but which must be specially laid the right way up, or
which require the fluke angle or profile to be adjusted for varying types of sea
bed, will not normally be accepted as anchoring equipment in accordance with these
Rules.
1.4.5 If ordinary ship type stockless bower anchors, not approved as high
holding power anchors, are to be used as Rule equipment, the mass of each anchor is
to be not less than 1,33 times that listed in Table 9.1.1 Equipment - Anchors and
chain cables for the units Equipment
Number.
1.4.6 The requirements for manufacture, proof testing and identification of
anchors are to be in accordance with Ch 10 Equipment for Mooring and Anchoring of the Rules for the Manufacture, Testing and
Certification of Materials (hereinafter referred to as the Rules for
Materials).
Table 9.1.1 Equipment - Anchors and
chain cables
Equipment number
|
Equipment Letter
|
High holding power anchor mass, in kg
|
Stud link chain cable
|
Exceeding
|
Not exceeding
|
Length per anchor, in metres
|
Diameter, in mm
|
Grade U1
|
Grade U2
|
Grade U3
|
50
|
70
|
A
|
140
|
110
|
14
|
12,5
|
|
70
|
90
|
B
|
180
|
110
|
16
|
14
|
|
90
|
110
|
C
|
230
|
110
|
17,5
|
16
|
|
110
|
130
|
D
|
270
|
110
|
19
|
17,5
|
|
130
|
150
|
E
|
310
|
137,5
|
20,5
|
17,5
|
|
150
|
175
|
F
|
360
|
137,5
|
22
|
19
|
|
175
|
205
|
G
|
430
|
137,5
|
24
|
20,5
|
|
205
|
240
|
H
|
500
|
137,5
|
26
|
22
|
20,5
|
240
|
280
|
I
|
590
|
165
|
28
|
24
|
22
|
280
|
320
|
J
|
680
|
165
|
30
|
26
|
24
|
320
|
360
|
K
|
770
|
165
|
32
|
28
|
24
|
360
|
400
|
L
|
860
|
192,5
|
34
|
30
|
26
|
400
|
450
|
M
|
970
|
192,5
|
36
|
32
|
28
|
450
|
500
|
N
|
1080
|
192,5
|
38
|
34
|
30
|
500
|
550
|
O
|
1190
|
192,5
|
40
|
34
|
30
|
550
|
600
|
P
|
1300
|
220
|
42
|
36
|
32
|
600
|
660
|
Q
|
1440
|
220
|
44
|
38
|
34
|
660
|
720
|
R
|
1580
|
220
|
46
|
40
|
36
|
720
|
780
|
S
|
1710
|
220
|
48
|
42
|
36
|
780
|
840
|
T
|
1850
|
220
|
50
|
44
|
38
|
840
|
910
|
U
|
1990
|
220
|
52
|
46
|
40
|
910
|
980
|
V
|
2140
|
247,5
|
54
|
48
|
42
|
980
|
1060
|
W
|
2290
|
247,5
|
56
|
50
|
44
|
1060
|
1140
|
X
|
2470
|
247,5
|
58
|
50
|
46
|
1140
|
1220
|
Y
|
2660
|
247,5
|
60
|
52
|
46
|
1220
|
1300
|
Z
|
2840
|
247,5
|
62
|
54
|
48
|
1300
|
1390
|
A
|
3040
|
247,5
|
64
|
56
|
50
|
1390
|
1480
|
B
|
3240
|
275
|
66
|
58
|
50
|
1480
|
1570
|
C
|
3440
|
275
|
68
|
60
|
52
|
1570
|
1670
|
D
|
3670
|
275
|
70
|
62
|
54
|
1670
|
1790
|
E
|
3940
|
275
|
73
|
64
|
56
|
1790
|
1930
|
F
|
4210
|
275
|
76
|
66
|
58
|
1930
|
2080
|
G
|
4500
|
275
|
78
|
68
|
60
|
2080
|
2230
|
H
|
4840
|
302,5
|
81
|
70
|
62
|
2230
|
2380
|
I
|
5180
|
302,5
|
84
|
73
|
64
|
2380
|
2530
|
J
|
5510
|
302,5
|
87
|
76
|
66
|
2530
|
2700
|
K
|
5850
|
302,5
|
90
|
78
|
68
|
2700
|
2870
|
L
|
6230
|
302,5
|
92
|
81
|
70
|
2870
|
3040
|
M
|
6530
|
302,5
|
95
|
84
|
73
|
3040
|
3210
|
N
|
6980
|
330
|
97
|
84
|
76
|
3210
|
3400
|
O
|
7430
|
330
|
100
|
87
|
78
|
3400
|
3600
|
P
|
7880
|
330
|
102
|
90
|
78
|
3600
|
3800
|
Q
|
8330
|
330
|
105
|
92
|
81
|
3800
|
4000
|
R
|
8780
|
330
|
107
|
95
|
84
|
4000
|
4200
|
S
|
9250
|
330
|
111
|
97
|
87
|
4200
|
4400
|
T
|
9700
|
357,5
|
114
|
100
|
87
|
4400
|
4600
|
U
|
10100
|
357,5
|
117
|
102
|
90
|
4600
|
4800
|
V
|
10600
|
357,5
|
120
|
105
|
92
|
4800
|
5000
|
W
|
11000
|
371,5
|
122
|
107
|
95
|
5000
|
5200
|
X
|
11600
|
371,5
|
124
|
111
|
97
|
5200
|
5500
|
Y
|
12100
|
371,5
|
127
|
111
|
97
|
5500
|
5800
|
Z
|
12700
|
371,5
|
130
|
114
|
100
|
5800
|
6100
|
A*
|
13400
|
371,5
|
132
|
117
|
102
|
6100
|
6500
|
B*
|
14100
|
371,5
|
|
120
|
107
|
6500
|
6900
|
C*
|
15000
|
385
|
|
124
|
111
|
6900
|
7400
|
D*
|
16000
|
385
|
|
127
|
114
|
7400
|
7900
|
E*
|
17500
|
385
|
|
132
|
117
|
7900
|
8400
|
F
|
18500
|
385
|
|
137
|
122
|
8400
|
8900
|
G*
|
19500
|
385
|
|
142
|
1127
|
8900
|
9400
|
H*
|
20500
|
385
|
|
147
|
132
|
9400
|
10000
|
I*
|
22000
|
385
|
|
152
|
132
|
10000
|
10700
|
J*
|
23500
|
385
|
|
157
|
137
|
10700
|
11500
|
K*
|
25000
|
385
|
|
157
|
142
|
11500
|
12400
|
L*
|
26500
|
385
|
|
162
|
147
|
12400
|
1340
|
M*
|
29000
|
385
|
|
|
152
|
13400
|
14600
|
N*
|
31500
|
385
|
|
|
157
|
14600
|
16000
|
O*
|
34500
|
385
|
|
|
162
|
NOTES
|
1. Consideration will be given to the acceptance of
equipment differing from these requirements on units which are
classed for restricted service (generally those with
geographical limitations ensuring service in sheltered or
shallow waters only).
|
2.
Special consideration will be given to units which are unmanned
during towed voyages and transfer moves.
|
1.5 High holding power anchors
1.5.2 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 Pt 4, Ch 9, 1.5 High holding power anchors 1.5.1, irrespective of the angle or
position at which they first settle on the sea bed when dropped from a normal type
of hawse pipe. In case of doubt, a demonstration of these abilities may be required.
The anchors are not to require prior adjustment or special placement on the sea
bottom.
1.6 Chain cables
1.6.2 Chain cables may be of mild steel, special quality steel or extra quality
steel in accordance with the requirements of Ch 10 Equipment for Mooring and Anchoring of the Rules for Materials and are to be graded in
accordance with Table 9.1.2 Anchor equipmant chain
grades.
Table 9.1.2 Anchor equipmant chain
grades
Grade
|
Material
|
Tensile strength
|
N/mm2
|
kgf/mm2
|
U1
|
Mild steel
|
300490
|
(3150)
|
U2(a)
|
Special quality steel
(wrought)
|
490690
|
(5070)
|
U2(b)
|
Special quality steel
(cast)
|
490690
|
(5070)
|
U3
|
Extra special quality
steel
|
690 min.
|
(70 min.)
|
1.6.3 Grade U1 material having a tensile stress of less than 400
N/mm2 (41 kgf/cm2) is not to be used in association with
high holding power anchors. Grade U3 material is to be used only for chain 20,5 mm
or more in diameter.
In this case, the length and breaking strength of the wire rope will be
specially considered.
1.7 Arrangements for working and stowing
anchors and cables
1.7.1 A windlass or winch of sufficient power and suitable for the type of
cable is to be provided for each of the anchor cables. Where Owners require
equipment significantly in excess of Rule requirements, it is their responsibility
to specify increased windlass or winch power.
1.7.2 The windlasses or winches are to be securely fitted and efficiently
bedded to suitable positions on the unit. The structural design integrity of the
bedplate is the responsibility of the Builder and windlass manufacturer.
1.7.3 The following performance criteria are to be used as a design basis for
the windlass:
- The windlass is to have sufficient power to
exert a continuous duty pull over a period of 30 minutes of:
36,79 N (3,75 kgf)
|
for Grade U1
chain,
|
41,68 N (4,25 kgf)
|
for Grade U2
chain,
|
41,6 N (4,75 kgf)
|
for Grade U3
chain,
|
where is the chain diameter, in mm.
- The windlass is to have sufficient power to exert, over a
period of at least two minutes, a pull equal to the greater of:
- short-term pull:
1,5 times the
continuous duty pull as defined in Pt 4, Ch 9, 1.7 Arrangements for working and stowing anchors and cables 1.7.3.(a).
- anchor breakout pull:
16,24
where
is length of chain cable per anchor, in metres, as
given by Table 9.1.1 Equipment - Anchors and
chain cables
is the mass of high holding power anchor, in kg, as
given in Table 9.1.1 Equipment - Anchors and
chain cables
- The windlass, with its braking system in action and in
conditions simulating those likely to occur in service, is to be able to
withstand, without permanent deformation or brake slip, a load, applied to
the cable, given by:
(44 0,08 ) N
(44 0,08 ) kgf )
where
is given in Table 9.1.3 .
NOTE
The performance criteria are to be
verified by means of shop tests in the case of windlasses manufactured
on an individual basis. Windlasses manufactured under LRs Type
Approval Scheme will not require shop testing on an individual
basis.
Cable grade
|
|
Windlass used in conjunction with chain
stopper
|
Chain stopper not fitted
|
U1
|
4,41
(0,45)
|
7,85
(0,8)
|
U2
|
6,18
(0,63)
|
11,0
(1,12)
|
U3
|
8,83
(0,9)
|
15,7
(1,6)
|
1.7.5 During trials on board the unit, the windlass should be shown to be
capable of raising the anchor from a depth of 82,5 m to a depth of 27,5 m at a mean
speed of not less than 9 m/min. Where the depth of water in the trial area is
inadequate, suitable equivalent simulating conditions will be considered as an
alternative.
1.7.6 The cable is to be capable of being paid out in the event of a power
failure.
1.7.8 An easy lead of the cables from the windlass or winch to the anchors and
chain lockers or wire storage drum is to be arranged. Where cables pass over or
through stoppers, these stoppers are to be manufactured from ductile material and be
designed to minimise the probability 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.
1.7.9 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.
If more than one chain is to be stowed in one locker then the individual cables are
to be separated by substantial divisions in the locker.
1.7.10 Provision is to be made for securing the inboard ends of the cables to
the structure. This attachment should have a working strength of not less than 63,7
kN (6,5 tonne-f) or 10 per cent of the breaking strength of the chain cable,
whichever is the greater, and the structure to which it is attached is to be
adequate for this load. Attention is drawn to the advantages of arranging that the
cable may be slipped in an emergency from an accessible position outside the chain
locker.
1.7.11 Where wire rope cables are used, these are to be stored on suitable
drums. The lead to the drums is to be such that the cables will reel onto the drums
reasonably evenly. If the drums are designed to apply the full winch hauling load to
the cables then the arrangements, using spooling gear or otherwise, are to ensure
even reeling of the cables onto the drums.
1.7.12 Fairleads, hawse pipes, anchor racks and associated structure and
components 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 plating and framing in way
of these components are to be reinforced as necessary. Columns, lower hulls,
footings and other areas likely to be damaged by anchors, chain cables and wire
ropes, etc. are to be suitably strengthened.
1.7.13 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:
- a weathertight connection can be made between the windlass
bedplate, or its equivalent, and the upper end of the chain pipe;
- 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
if the sea is liable to break over the windlass; and
- for column-stabilised units, see
Pt 4, Ch 7, 4.7 Weathertight integrity related to stability 4.7.2.
1.7.14 All anchors are to be stowed to prevent moving during transit.
1.8 Testing of equipment
1.8.1 All anchors and chain cables are to be tested at establishments and on
machines recognised by LR and under the supervision of LRs Surveyors or other
Officers recognised by LR, and in accordance with the Rules for Materials.
1.8.2 Test certificates showing particulars of weights of anchors, or size and
weight of cable and of the test loads applied are to be furnished. These
certificates are to be examined by the Surveyors when the anchors and cables are
placed on board the unit.
1.8.3 Steel wire ropes are to be tested as required by the Rules for
Materials.
|