Meer info
     

05/04/1966 Uitwateringsverdrag
Internationaal verdrag van 5 april 1966 betreffende de uitwatering van schepen

Chapter III Freeboards

Regulation 27 Types of ships

(1)

For the purposes of freeboard computation, ships shall be divided into type “A” and type “B” .

(2)

A type “A” ship is one which:
(a)
is designed to carry only liquid cargoes in bulk;
(b)
has a high integrity of the exposed deck with only small access openings to cargo compartments, closed by watertight gasketed covers of steel or equivalent material; and
(c)
has low permeability of loaded cargo compartments.

(3)

A type “A” ship, if over 150 m in length, to which a freeboard less than type “B” has been assigned, when loaded in accordance with the requirements of paragraph (11), shall be able to withstand the flooding of any compartment or compartments, with an assumed permeability of 0.95, consequent upon the damage assumptions specified in paragraph (12), and shall remain afloat in a satisfactory condition of equilibrium, as specified in paragraph (13). In such a ship, the machinery space shall be treated as a floodable compartment, but with a permeability of 0.85.

(4)

A type “A” ship shall be assigned a freeboard not less than that based on table 28.1.

(5)

All ships which do not come within the provisions regarding type “A” ships in paragraphs (2) and (3) shall be considered as type “B” ships.

(6)

Type “B” ships, which in position 1 have hatch covers which are permitted by the Administration to comply with the requirements of regulation 15 (other than paragraph (6)) or which are fitted with securing arrangements accepted under the provisions of regulation 16(6), shall be assigned freeboards based upon the values given in table 28.2, increased by the values given in table 27.1:
Table 27.1 – Freeboard increase over tabular freeboard for type ” B” ships, for ships with hatch covers complying with the provisions of regulation 15 (other than paragraph (6))
Length Of Ship
(m)
Freeboard increase
(mm)
Length of ship
(m)
Freeboard increase
(mm)
Length of ship
(m)
Freeboard increase
(mm)
≤ 108
50
139
175
170
290
109
52
140
181
171
292
110
55
141
186
172
294
111
57
142
191
173
297
112
59
143
196
174
299
113
62
144
201
175
301
114
64
145
206
176
304
115
68
146
210
177
306
116
70
147
215
178
308
117
73
148
219
179
311
118
76
149
224
180
313
119
80
150
228
181
315
120
84
151
232
182
318
121
87
152
236
183
320
122
91
153
240
184
322
123
95
154
244
185
325
124
99
155
247
186
327
125
103
156
251
187
329
126
108
157
254
188
332
127
112
158
258
189
334
128
116
159
261
190
336
129
121
160
264
191
339
130
126
161
267
192
341
131
131
162
270
193
343
132
136
163
273
194
346
133
142
164
275
195
348
134
147
165
278
196
350
135
153
166
280
197
353
136
159
167
283
198
355
137
164
168
285
199
357
138
170
169
287
200
358
Freeboards at intermediate lengths of ship shall be obtained by linear interpolation. Ships above 200 m in length shall be dealt with by the Administration.

(7)

Type “B” ships, which in position 1 have hatchways fitted with hatch covers complying with the requirements of regulation 16(2) through (5), shall, except as provided in paragraphs (8) to (13) inclusive, be assigned freeboards based on table 28.2.

(8)

Any type “B” ship of over 100 m in length may be assigned freeboards less than those required under paragraph (7), provided that, in relation to the amount of reduction granted, the Administration is satisfied that:
(a)
the measures provided for the protection of the crew are adequate;
(b)
the freeing arrangements are adequate;
(c)
the covers in position 1 and 2 comply with the provisions of regulation 16(1) through (5) and (7); and
(d)
the ship, when loaded in accordance with the requirements of paragraph (11), shall be able to withstand the flooding of any compartment or compartments, with an assumed permeability of 0.95, consequent upon the damage assumptions specified in paragraph (12), and shall remain afloat in a satisfactory condition of equilibrium, as specified in paragraph (13). In such a ship, if over 150 m in length, the machinery space shall be treated as a floodable compartment, but with a permeability of 0.85.

(9)

In calculating the freeboards for type “B” ships which comply with the requirements of paragraphs (8), (11), (12) and (13), the values from table 28.2 shall not be reduced by more than 60 % of the difference between the tabular values in tables 28.1 and 28.2 for the appropriate ship lengths.

(10)

(a)
The reduction in tabular freeboard allowed under paragraph (9) may be increased up to the total difference between the values in table 28.1 and those in table 28.2 on condition that the ship complies with the requirements of:
(i)
regulation 26, other than paragraph (5), as if it were a type “A” ship;
(ii)
paragraphs (8), (11) and (13); and
(iii)
paragraph (12), provided that throughout the length of the ship any one transverse bulkhead will be assumed to be damaged, such that two adjacent fore and aft compartments shall be flooded simultaneously, except that such damage will not apply to the boundary bulkheads of a machinery space.
(b)
In such a ship, if over 150 m in length, the machinery space shall be treated as a floodable compartment, but with a permeability of 0.85.

(11)

The initial condition of loading before flooding shall be determined as follows:
(a)
The ship is loaded to its summer load waterline on an imaginary even keel.
(b)
When calculating the vertical centre of gravity, the following principles apply:
(i)
homogeneous cargo is carried;
(ii)
all cargo compartments, except those referred to under subparagraph (iii), but including compartments intended to be partially filled, shall be considered fully loaded except that in the case of fluid cargoes each compartment shall be treated as 98 % full;
(iii)
if the ship is intended to operate at its summer load waterline with empty compartments, such compartments shall be considered empty, provided the height of the centre of gravity so calculated is not less than as calculated under subparagraph (ii);
(iv)
[50 per cent of the ship's total capacity of tanks and spaces fitted to contain each type of consumables and stores is allowed for.] It shall be assumed that for each type of liquid at least one transverse pair or a single centreline tank has maximum free surface, and the tank or combination of tanks to be taken into account shall be those where the effect of free surfaces is the greatest; in each tank the centre of gravity of the contents shall be taken at the centre of volume of the tank. The remaining tanks shall be assumed either completely empty or completely filled, and the distribution of consumable liquids between these tanks shall be effected so as to obtain the greatest possible height above the keel for the centre of gravity;
(v)
[ballast water tanks shall normally be considered to be empty and no free surface correction shall be made for them;]
[(vi)
[Alternative treatment for free surface may be considered when developing the final condition for application of damage specified in regulation 27(12):
(aa)
Method 1 (appropriate to virtual corrections). The virtual centre of gravity for the initial condition is determined as follows:
i.
the loading condition shall be developed in accordance with paragraphs (i) to (iv);
ii.
the correction for the free surfaces is added to the vertical centre of gravity;
iii.
one virtual initial condition with all compartments empty is generated on summer load line draught with level trim, using the vertical centre of gravity from the above loading condition; and
iv.
the damage cases will be checked for compliance with the damage stability criteria using the above initial condition.
(bb)
Method 2 (appropriate to the use of actual free surface moments according to the assumed tank fillings for damage case). The virtual centre of gravity for the initial condition is determined as follows:
i.
the loading condition shall be developed in accordance with paragraphs (i) to (iv);
ii.
one virtual initial condition for each damage case with liquid-filled compartments may be generated on summer load line draught with level trim, using the initial virtual condition with filled compartments generated on summer load line draught with level trim. Using the vertical centre of gravity and free surface correction from the above loading condition separate calculations for each damage case are performed, only the liquid-filled compartments to be damaged are left empty before damage; and
iii.
the damage cases will be checked for compliance with the damage stability criteria using above initial conditions (one initial condition for each damage case).]
[(vii)
weights shall be calculated on the basis of the following values for specific gravities:
salt water 1025
fresh water 1000
oil fuel 0950
diesel oil 0900
lubricating oil 0900.

(12)

The following principles regarding the character of the assumed damage apply:
(a)
The vertical extent of damage in all cases is assumed to be from the base line upwards without limit.
(b)
The transverse extent of damage is equal to B/5 or 11.5 m, whichever is the lesser, measured inboard from the side of the ship perpendicularly to the centreline at the level of the summer load waterline.
(c)
If damage of a lesser extent than specified in subparagraphs (a) and (b) results in a more severe condition, such lesser extent shall be assumed.
(d)
Except where otherwise required by paragraph (10)(a), the flooding shall be confined to a single compartment between adjacent transverse bulkheads, provided that the inner longitudinal boundary of the compartment is not in a position within the transverse extent of assumed damage. Transverse boundary bulkheads of wing tanks, which do not extend over the full breadth of the ship shall be assumed not to be damaged, provided that they extend beyond the transverse extent of assumed damage prescribed in subparagraph (b). If in a transverse bulkhead there are steps or recesses of not more than 3 m in length, located within the transverse extent of assumed damage as defined in subparagraph (b), such transverse bulkhead may be considered intact and the adjacent compartment may be floodable singly. If, however, within the transverse extent of assumed damage there is a step or recess of more than 3 m in length in a transverse bulkhead, the two compartments adjacent to this bulkhead shall be considered as flooded. The step formed by the afterpeak bulkhead and the afterpeak tank top shall not be regarded as a step for the purpose of this regulation.
(e)
Where a main transverse bulkhead is located within the transverse extent of assumed damage and is stepped in way of a double bottom or side tank by more than 3 m, the double bottom or side tanks adjacent to the stepped portion of the main transverse bulkhead shall be considered as flooded simultaneously. If this side tank has openings into one or several holds, such as grain feeding holes, such hold or holds shall be considered as flooded simultaneously. Similarly, in a ship designed for the carriage of fluid cargoes, if a side tank has openings into adjacent compartments, such adjacent compartments shall be considered as empty and as being flooded simultaneously. This provision is applicable even where such openings are fitted with closing appliances, except in the case of sluice valves fitted in bulkheads between tanks and where the valves are controlled from the deck. Manhole covers with closely spaced bolts are considered equivalent to the unpierced bulkhead, except in the case of openings in topside tanks making the topside tanks common to the holds.
(f)
Where the flooding of any two adjacent fore and aft compartments is envisaged, main transverse watertight bulkheads shall be spaced at least 1/3 L2/3 or 14.5 m, whichever is the lesser, in order to be considered effective. Where transverse bulkheads are spaced at a lesser distance, one or more of these bulkheads shall be assumed as non- existent in order to achieve the minimum spacing between bulkheads. Condition of equilibrium

(13)

The condition of equilibrium after flooding shall be regarded as satisfactory provided:
(a)
The final waterline after flooding, taking into account sinkage, heel and trim, is below the lower edge of any opening through which progressive downflooding may take place. Such openings shall include air pipes, ventilators (even if they comply with regulation 19(4)) and openings which are closed by means of weathertight doors (even if they comply with regulation 12) or hatch covers (even if they comply with regulation 16(1) through (5)), and may exclude those openings closed by means of manhole covers and flush scuttles (which comply with regulation 18), cargo hatch covers of the type described in regulation 27(2), remotely operated sliding watertight doors, and sidescuttles of the non-opening type (which comply with regulation 23). However, in the case of doors separating a main machinery space from a steering gear compartment, watertight doors may be of a hinged, quick-acting type kept closed at sea whilst not in use, provided also that the lower sill of such doors is above the summer load waterline.
(b)
If pipes, ducts or tunnels are situated within the assumed extent of damage penetration as defined in paragraph (12)(b), arrangements shall be made so that progressive flooding cannot thereby extend to compartments other than those assumed to be floodable in the calculation for each case of damage.
(c)
The angle of heel due to unsymmetrical flooding does not exceed 15°. If no part of the deck is immersed, an angle of heel of up to 17° may be accepted.
(d)
The metacentric height in the flooded condition is positive.
(e)
When any part of the deck outside the compartment assumed flooded in a particular case of damage is immersed, or in any case where the margin of stability in the flooded condition may be considered doubtful, the residual stability is to be investigated. It may be regarded as sufficient if the righting lever curve has a minimum range of 20° beyond the position of equilibrium with a maximum righting lever of at least 0.1 m within this range. The area under the righting lever curve within this range shall be not less than 0.0175 m·rad. The Administration shall give consideration to the potential hazard presented by protected or unprotected openings which may become temporarily immersed within the range of residual stability.
(f)
The Administration is satisfied that the stability is sufficient during intermediate stages of flooding.
(g)
[Compliance with the residual stability criteria specified in paragraphs (a), (c), (d) and (e) above is not required to be demonstrated in service loading conditions using a stability instrument, stability software or other approved method.]

(14)

A lighter, barge or other ship without independent means of propulsion shall be assigned a freeboard in accordance with the provisions of these regulations. Barges which meet the requirements of paragraphs (2) and (3) may be assigned type “A” freeboards:
(a)
The Administration should especially consider the stability of barges with cargo on the weather deck. Deck cargo can only be carried on barges to which the ordinary type “B” freeboard is assigned.
(b)
However, in the case of barges which are unmanned, the requirements of regulations 25, 26(3), 26(4) and 39 shall not apply
(c)
Such unmanned barges which have on the freeboard deck only small access openings closed by watertight gasketed covers of steel or equivalent material may be assigned a freeboard 25 % less than those calculated in accordance with these regulations.
Wetshistoriek
(11) en (13) gewijzigd bij Res. MSC.345(91), met ingang van 1 juli 2014.

Regulation 28 Freeboard tables

(1) Type “A” ships

The tabular freeboard for type ” A” ships shall be determined from table 28.1:
Table 28.1 Freeboard table for type “A” ships
Length of Ship
(m)
Freeboard increase
(mm)
Length of Ship
(m)
Freeboard increase
(mm)
Length of ship
(m)
Freeboard increase
(mm)
24
200
51
455
78
814
25
208
52
467
79
828
26
217
53
478
80
841
27
225
54
490
81
855
28
233
55
503
82
869
29
242
56
516
83
883
30
250
57
530
84
897
31
258
58
544
85
911
32
267
59
559
86
926
33
275
60
573
87
940
34
283
61
587
88
955
35
292
62
600
89
969
36
300
63
613
90
984
37
308
64
626
91
999
38
316
65
639
92
1014
39
325
66
653
93
1029
40
334
67
666
94
1044
41
344
68
680
95
1059
42
354
69
693
96
1074
43
364
70
706
97
1089
44
374
71
720
98
1105
45
385
72
733
99
1120
46
396
73
746
100
1135
47
408
74
760
101
1151
48
420
75
773
102
1166
50
443
77
800
104
1196
105
1212
168
2240
231
2880
106
1228
169
2254
232
2888
107
1244
170
2268
233
2895
108
1260
171
2281
234
2903
109
1276
172
2294
235
2910
110
1293
173
2307
236
2918
111
1309
174
2320
237
2925
112
1326
175
2332
238
2932
113
134
176
2345
239
2939
114
1359
177
2357
240
2946
115
1376
178
2369
241
2953
116
1392
179
2381
242
2959
117
1409
180
2393
243
2966
118
1426
182
2405
244
2973
119
1442
182
2416
245
2979
120
1459
183
2428
246
2986
121
1476
184
2440
247
2993
122
1494
185
2451
248
3000
123
1511
186
2463
249
3006
124
1528
187
2474
250
3012
125
1546
188
2486
251
3018
126
1563
189
2497
252
3024
127
1580
190
2508
253
3030
128
1598
191
2519
254
3036
129
1615
192
2530
255
3042
130
1632
193
2541
256
3048
131
1650
194
2552
257
3054
132
1667
195
2562
258
3060
133
1684
196
2572
259
3066
134
1702
197
2582
260
3072
135
1719
198
2592
261
3078
136
1736
199
2602
262
3084
137
1753
200
2612
263
3089
138
1770
201
2622
264
3095
139
1787
202
2632
265
3101
140
1803
203
2641
266
3106
141
1820
204
2650
267
3112
142
1837
206
2659
268
3117
143
1853
206
2669
269
3123
144
1870
207
2678
270
3128
145
1886
208
2687
271
3133
146
1903
209
2696
272
3138
147
1919
210
2705
273
3143
148
1935
211
2714
274
3148
149
1952
212
2723
275
3153
150
1968
213
2732
276
3158
151
1984
214
2741
277
3163
152
2000
215
2749
278
3167
153
2016
216
2758
279
3172
154
2032
217
2767
280
3176
155
2048
218
2775
281
3181
156
2064
219
2784
282
3185
157
2080
220
2792
283
3189
158
2096
221
2801
284
3194
159
2111
222
2809
285
3198
160
2126
223
2817
286
3202
161
2141
224
2825
287
3207
162
2155
225
2833
288
3211
163
2169
226
2841
289
3215
164
2184
227
2849
290
3220
165
2198
228
2857
291
3224
166
2212
229
2865
292
3228
167
2226
230
2872
293
3233
294
3237
318
3325
342
3387
295
3241
319
3328
343
3389
296
3246
320
3331
344
3392
297
3250
321
3334
345
3394
298
3254
322
3337
346
3396
299
3258
323
3339
347
3399
300
3262
324
3342
348
3401
301
3266
325
3345
349
3403
302
3270
326
3347
350
3406
303
3274
327
3350
351
3408
304
3278
328
3353
352
3410
305
3281
329
3355
353
3412
306
3285
330
3358
354
3414
307
3288
331
3361
355
3416
308
3292
332
3363
356
3418
309
3295
333
3366
357
3420
310
3298
334
3368
358
3422
311
3302
335
3371
359
3423
312
3305
336
3373
360
3425
313
3308
337
3375
361
3427
314
3312
338
3378
362
3428
315
3315
339
3380
363
3430
316
3318
340
3382
364
3432
317
3322
341
3385
365
3433
Freeboards at intermediate lengths of ship shall be obtained by linear interpolation. Ships above 365 m in length shall be dealt with by the Administration.

(2) Type “B” ships

The tabular freeboard for type “B” ships shall be determined from table 28.2:
Table 28.2 Freeboard table for type “B” ships
Length of Ship
(m)
Freeboard increase
(mm)
Length of Ship
(m)
Freeboard increase
(mm)
Length of ship
(m)
Freeboard increase
(mm)
24
200
70
721
116
1609
25
208
71
738
117
1630
26
217
72
754
118
1651
27
225
73
569
119
1671
28
233
74
784
120
1690
29
242
75
800
121
1709
30
250
76
816
122
1729
31
258
77
833
123
1750
32
267
78
850
124
1771
33
275
79
868
125
1793
34
283
80
887
126
1815
35
292
81
905
127
1837
36
300
82
923
128
1859
37
308
83
842
129
1880
38
316
84
960
130
1901
39
325
85
978
131
1921
40
334
86
996
132
1940
41
344
87
1015
133
1959
42
354
88
1034
134
1979
43
364
89
1054
135
2000
44
374
90
1075
136
2021
45
385
91
1096
137
2043
46
396
92
1116
138
2065
47
408
93
1135
139
2087
48
420
94
1154
140
2109
49
432
95
1172
141
2130
50
443
96
1190
142
2151
51
455
97
1209
143
2171
52
467
98
1229
144
2190
53
478
99
1250
145
2209
54
490
100
1271
146
2229
55
503
101
1293
147
2250
56
516
102
1315
148
2271
57
530
103
1337
149
2293
58
544
104
1359
150
2315
59
559
105
1380
151
2334
60
573
106
1401
152
2354
61
587
107
1421
153
2375
62
601
108
1440
154
2396
63
615
109
1459
155
2418
64
629
110
1479
156
2440
65
644
111
1500
157
2460
66
659
112
1521
158
2480
67
674
113
1543
159
2500
68
689
114
1565
160
2520
69
705
115
1587
161
2540
162
2560
225
3660
288
4490
163
2580
226
3675
289
4502
164
2600
227
3690
290
4513
165
2620
228
3705
291
4525
166
2640
229
3720
292
4537
167
2660
230
3735
293
4548
168
2680
231
3750
294
4560
169
2698
232
3765
295
4572
170
2716
233
3780
296
4583
171
2735
234
3795
297
4595
172
2754
235
3808
298
4607
173
2774
236
3821
299
4618
174
2795
237
3835
300
4630
175
2815
237
3849
301
4642
176
2835
239
3864
302
4654
177
2855
240
3880
303
4665
178
2875
241
3893
304
4676
179
2895
242
3906
305
4686
180
2915
243
3920
306
4695
181
2933
244
3934
307
4704
182
2952
245
3949
308
4714
183
2970
246
3965
309
4725
184
2988
247
3978
310
4736
185
3007
248
3992
311
4748
186
3025
249
4005
312
4757
187
3044
250
4018
313
4768
188
3062
251
4032
314
4779
189
3080
252
4045
315
4790
190
3098
253
4058
316
4801
191
3116
254
4072
317
4812
192
3134
255
4085
318
4823
193
3151
256
4098
319
4834
194
3167
257
4112
320
4844
195
3185
258
4125
321
4855
196
3202
259
4139
322
4866
197
3219
260
4152
323
4878
198
3235
261
4165
324
4890
199
3249
262
4177
325
4899
200
3264
263
4189
326
4909
201
3280
264
4201
327
4920
202
3296
265
4214
328
4931
203
3313
266
4227
329
4943
204
3330
267
4240
330
4955
205
3347
268
4252
331
4965
206
3363
269
4264
332
4975
207
3380
270
4276
333
4985
208
339
271
4289
334
4995
209
3413
272
4302
335
5005
210
3430
273
4345
336
5015
211
3445
274
4327
337
5025
212
3460
275
4339
338
5035
213
3475
276
4350
339
5045
214
3490
277
4362
340
5055
215
3505
278
4373
341
5065
216
3520
279
4385
342
5075
217
3537
280
4397
343
5086
218
3554
281
4408
344
5097
219
3570
282
4420
345
5108
220
3586
283
4432
346
5119
221
3601
284
4443
347
5130
222
3615
285
4455
348
5140
223
3630
286
4467
349
5150
224
3645
287
4478
350
5160
351
5170
356
5220
361
5268
352
5180
357
5230
362
5276
353
5190
358
5240
363
5285
354
5200
359
5250
364
5294
355
5210
360
5260
365
5303
Freeboards at intermediate lengths of Freeboards at intermediate lengths of by linear interpolation. Ships above 365 m in length shall be dealt with by the Administration.

Regulation 29 Correction to the freeboard for ships under 100 m in length

The tabular freeboard for a type “B” ship of between 24 m and 100 m in length having enclosed superstructures with an effective length of up to 35 % of the length of the ship shall be increased by:
7.5·(100 – L)·(0.35 – E1/L) (mm)
where
L is the length of the ship in m; and
E1 is the effective length E of superstructure in m as defined in regulation 35, but excluding the length of trunks.

Regulation 30 Correction for block coefficient

Where the block coefficient (Cb) exceeds 0.68, the tabular freeboard specified in regulation 28 as modified, if applicable, by regulations 27(8), 27(10) and 29 shall be multiplied by the factor:
(Cb + 0.68)/1.36
The block coefficient is not to be taken greater than 1.0.

Regulation 31 Correction for depth

(1)

Where D exceeds L/15 the freeboard shall be increased by (D – L/15) R mm, where R is L/0.48 at lengths less than 120 m and 250 at 120 m length and above.

(2)

Where D is less than L/15 no reduction shall be made, except in a ship with an enclosed superstructure covering at least 0.6L amidships, with a complete trunk, or combination of detached enclosed superstructures and trunks which extend all fore and aft, where the freeboard shall be reduced at the rate prescribed in paragraph (1).

(3)

Where the height of the superstructure or trunk is less than the corresponding standard height, the calculated reduction shall be corrected in the ratio of the height of the actual superstructure or trunk to the applicable standard height, as defined in regulation 33.

Regulation 32 Correction for position of deck line

Where the actual depth to the upper edge of the deck line is greater or less than D, the difference between the depths shall be added to or deducted from the freeboard.

Regulation 32-1 Correction for recess in freeboard deck

(1)

Where a recess is arranged in the freeboard deck, and it does not extend to the sides of the ship, the freeboard calculated without regard to the recess shall be corrected for the consequent loss of buoyancy. The correction shall be equal to the value obtained by dividing the volume of the recess by the waterplane area of the ship at 85 % of the least moulded depth (see figure 32-1.1).

(2)

The correction shall be an addition to the freeboard obtained after all other corrections have been applied, except bow height correction.

(3)

Where the freeboard, corrected for lost buoyancy as above, is greater than the minimum geometric freeboard determined on the basis of a moulded depth measured to the bottom of the recess, the latter value may be used.
Figure 32-1.1
Correction is the addition to freeboard equal to:
l × b × dr
WP Area at 0.85D

Regulation 33 Standard height of superstructure

The standard height of a superstructure shall be as given in the following table:
Table 33.1
Standard height (in m)
L (m)
Raised quarterdeck
All other superstructures
30 or less
0.9
1.8
75
1.2
1.8
125 or more
1.8
2.3
The standard heights at intermediate lengths of the ship shall be obtained by linear interpolation.

Regulation 34 Length of superstructure

(1)

Except as provided in paragraph (2), the length of a superstructure (S) shall be the mean length of the parts of the superstructure which lie within the length (L).
Where a superstructure bulkhead is recessed, the effective length of the superstructure shall be reduced by an amount equal to the area of the recess in plan view divided by the breadth of the superstructure at the midlength of the recess. Where the recess is unsymmetrical about the centreline, the largest portion of the recess shall be considered as applying to both sides of the ship. A recess need not be decked over.

(2)

Where the end bulkhead of an enclosed superstructure extends in a fair convex curve beyond its intersection with the superstructure sides, the length of the superstructure may be increased on the basis of an equivalent plane bulkhead. This increase shall be two- thirds of the fore and aft extent of the curvature. The maximum curvature which may be taken into account in determining this increase is one-half the breadth of the superstructure at the point of intersection of the curved end of the superstructure with its side.
Where there is an extension to a superstructure, which extension has a breadth on each side of the centre line at least 30 % of the breadth of the ship, the effective length of the superstructure may be increased by considering an equivalent superstructure bulkhead in the form of a parabola. This parabola shall extend from the extension at the centreline and pass through the junction of the actual superstructure bulkhead with the sides of the extension and extend to the sides of the ship. This parabola shall be completely contained within the boundary of the superstructure and its extensions.
If the superstructure is set-in from the side, up to the limit allowed under regulation 3(10), the equivalent bulkhead should be calculated on the basis of the actual breadth of the superstructure (and not the breadth of the ship).

(3)

Superstructures which have sloped end bulkheads shall be dealt with in the following manner:
(a)
When the height of superstructure, clear of the slope, is equal to or smaller than the standard height, length S is to be obtained as shown in figure 34.1.
Figure 34.1 – Height of superstructure equal to or smaller than the standard height h
(b)
When the height is greater than the standard, length S is to be obtained as shown in figure 34.2.
Figure 34.2 – Height of superstructure greater than the standard height
(c)
The foregoing will apply only when the slope, related to the base line, is 15° or greater. Where the slope is less than 15°, the configuration shall be treated as sheer.

Regulation 35 Effective length of superstructure

(1)

Except as provided for in paragraph (2), the effective length (E) of an enclosed superstructure of standard height shall be its length.

(2)

In all cases where an enclosed superstructure of standard height is set-in from the sides of the ship as permitted in regulation 3(10), the effective length shall be the length modified by the ratio of b/Bs, where:
b is the breadth of the superstructure at the middle of its length; and
Bs is the breadth of the ship at the middle of the length of the superstructure.
Where a superstructure is set-in for a part of its length, this modification shall be applied only to the set-in part.

(3)

Where the height of an enclosed superstructure is less than the standard height, the effective length shall be its length reduced in the ratio of the actual height to the standard height. Where the height exceeds the standard, no increase shall be made to the effective length of the superstructure (see figures 34.1 and 34.2).
Where the height, clear of the slope, of a superstructure which has sloped end bulkheads is less than the standard height, its effective length E shall be its length S as obtained from figure 34.1, reduced in the ratio of the actual height to the standard height.
Where a poop or forecastle of less than standard height is fitted on a ship with excessive sheer but without any superstructure within 0.2L amidships, credit may be given to the height of the poop or forecastle by increasing the actual height by the difference between the actual and the standard sheer profiles. The deduction for excess sheer in accordance with regulation 38(16) is not to be granted.

(4)

The effective length of a raised quarter deck, if fitted with an intact front bulkhead, shall be its length up to a maximum of 0.6L. Where the bulkhead is not intact, the raised quarter deck shall be treated as a poop of less than standard height.
The maximum effective length of 0.6L of a raised quarterdeck is to be measured from the after perpendicular, even where a poop is fitted in conjunction with the raised quarterdeck.

(5)

Superstructures which are not enclosed shall have no effective length.

Regulation 36 Trunks

(1)

A trunk or similar structure which does not extend to the sides of the ship shall be regarded as efficient on the following conditions:
(a)
the trunk is at least as strong as a superstructure;
(b)
the hatchways are in the trunk deck, the hatchway coamings and covers comply with the requirements of regulations 13 to 16 inclusive and the width of the trunk deck stringer provides a satisfactory gangway and sufficient lateral stiffness. However, small access openings with watertight covers may be permitted in the freeboard deck;
(c)
a permanent working platform fore and aft fitted with guard rails is provided by the trunk deck, or by detached trunks connected to superstructures by efficient permanent gangways;
(d)
ventilators are protected by the trunk, by watertight covers or by other equivalent means;
(e)
open rails are fitted on the weather parts of the freeboard deck in way of the trunk for at least half their length or, alternatively, freeing port area in the lower part of the bulwarks, subject to regulation 24(2), of 33 % of the total area of the bulwarks is provided;
(f)
the machinery casings are protected by the trunk, by a superstructure of at least standard height, or by a deckhouse of the same height and of equivalent strength;
(g)
the breadth of the trunk is at least 60 % of the breadth of the ship; and
(h)
where there is no superstructure, the length of the trunk is at least 0.6L.

(2)

The full length of an efficient trunk reduced in the ratio of its mean breadth to B shall be its effective length.

(3)

The standard height of a trunk is the standard height of a superstructure other than a raised quarter deck.

(4)

Where the height of a trunk is less than the standard height, its effective length shall be reduced in the ratio of the actual to the standard height. Where the height of hatchway coamings on the trunk deck is less than that required under regulation 14-1, a reduction from the actual height of trunk shall be made which corresponds to the difference between the actual and the required height of coaming.

(5)

Where the trunk height is less than standard and the trunk hatch coamings are also of less than standard height, or omitted entirely, the reduction from the actual height of trunk on account of insufficient hatch coaming height shall be taken as the difference between 600 mm and the actual height of coaming, or 600 mm if no hatch coamings are fitted. Reduction in the actual height of trunk shall not be required in cases where only small hatches with less than standard height are fitted in the trunk deck for which dispensation from the requirement of standard coaming height may be given.

(6)

Continuous hatchways may be treated as a trunk in the freeboard computation, provided the provisions of this paragraph are complied with in all respects. The trunk deck stringer referred to in paragraph (1)(b) may be fitted outboard of the trunk side bulkhead in association with the following:
(a)
the stringer so formed is to provide a clear walkway of at least 450 mm in width on each side of the ship;
(b)
the stringer is to be of solid plate, efficiently supported and stiffened;
(c)
the stringer is to be as high above the freeboard deck as practicable. In the freeboard calculation, the trunk height is to be reduced by at least 600 mm or by the actual difference between the top of the trunk and the stringer, whichever is greater;
(d)
hatch cover securing appliances are to be accessible from the stringer or walkway; and
(e)
the breadth of the trunk is to be measured between the trunk side bulkheads.

(7)

Where the trunk adjoining the superstructures such as poop, bridge or forecastle is included in the calculation of freeboard, openings shall not be arranged in that part of the bulkhead which is common for the trunk and superstructure. A relaxation may be made for small openings such as for piping, cable or manholes with covers attached by means of bolts.

(8)

The sides of a trunk included in the calculation of freeboard shall be intact. Side scuttles of the non-opening type and bolted manhole covers may be allowed.

Regulation 37 Deduction for superstructures and trunks

(1)

Where the effective length of superstructures and trunks is 1L, the deduction from the freeboard shall be 350 mm at 24 m length of ship, 860 mm at 85 m length and 1070 mm at 122 m length and above. Deductions at intermediate lengths shall be obtained by linear interpolation.

(2)

Where the total effective length of superstructures and trunks is less than 1L, the deduction shall be a percentage obtained from the following table:
Table 37.1 – Percentage of deduction for type “A” and “B” ships
 
Total Effective Length of Superstructures and Trunks
 
0
0.1L
0.2L
0.3L
0.4L
0.5L
0.6L
0.7L
0.8L
0.9L
1.0L
Percentage of deduction for all types of super-structures
0
7
14
21
31
41
52
63
75.3
87.7
100
Percentages at intermediate lengths of superstructures and trunks shall be obtained by linear interpolation.

(3)

For ships of type “B” where the effective length of a forecastle is less than 0.07L no deduction is allowed.

Regulation 38 Sheer

(1)

The sheer shall be measured from the deck at side to a line of reference drawn parallel to the keel through the sheer line amidships.

(2)

In ships designed with a rake of keel, the sheer shall be measured in relation to a reference line drawn parallel to the design load waterline.

(3)

In flush deck ships and in ships with detached superstructures the sheer shall be measured at the freeboard deck.

(4)

In ships with topsides of unusual form in which there is a step or break in the topsides, the sheer shall be considered in relation to the equivalent depth amidships.

(5)

In ships with a superstructure of standard height which extends over the whole length of the freeboard deck, the sheer shall be measured at the superstructure deck. Where the height exceeds the standard, the least difference (Z) between the actual and standard heights shall be added to each end ordinate. Similarly, the intermediate ordinates at distances of 1/6L and 1/3L from each perpendicular shall be increased by 0444Z and 0111Z, respectively. Where there is an enclosed poop or forecastle superimposed on the superstructure, sheer credit shall be allowed for such a poop or forecastle, according to the method of paragraph (12) as shown in figure 38.1.

(6)

Where the deck of an enclosed superstructure has at least the same sheer as the exposed freeboard deck, the sheer of the enclosed portion of the freeboard deck shall not be taken into account.

(7)

Where an enclosed poop or forecastle is of standard height with greater sheer than that of the freeboard deck, or is of more than standard height, an addition to the sheer of the freeboard deck shall be made as provided in paragraph (12). Where a poop or forecastle consists of two layers, the method shown in figure 38.2 shall be used.
Figure 38.2
In figures 38.1and 38.2, the following definitions apply:
Z is as defined in paragraph (5); and
Zv is the end ordinate of a virtual standard parabolic curve taken through the point “X”. If Zv is greater than (Z + h), the end ordinate shall be (Z + h), in which case point “X” shall be disregarded and curve (2) not taken into account.
When the length of the first tier superstructure is greater than 0.5l, the virtual standard parabolic curve shall commence at amidships as indicated in figure 38.1.

(8)

The ordinates of the standard sheer profile are given in the following table:
Table 38.1 Standard sheer profile (where L is in m)
 
Station
Ordinate (in mm)
Factor
After half
After perpendicular
1/6 L from A.P.
1/3 L from A.P.
Amidships
25 (L/3 + 10)
11.1 (L/3 + 10)
2.8 (L/3 + 10)
0
1
3
3
1
Forward half
Amidships
1/3 L from F.P.
1/6 L from F.P.
Forward perpendicular
0
5.6 (L/3 + 10)
22.2 (L/3 + 10)
50 (L/3 + 10)
1
3
3
1

(9)

Where the sheer profile differs from the standard, the four ordinates of each profile in the forward or after half shall be multiplied by the appropriate factors given in the above table of ordinates. The difference between the sums of the respective products and those of the standard divided by 8 measures the deficiency or excess of sheer in the forward or after half. The arithmetical mean of the excess or deficiency in the forward and after halves measures the excess or deficiency of sheer.

(10)

Where the after half of the sheer profile is greater than the standard and the forward half is less than the standard, no credit shall be allowed for the part in excess and deficiency only shall be measured.

(11)

Where the forward half of the sheer profile exceeds the standard, and the after portion of the sheer profile is not less than 75 % of the standard, credit shall be allowed for the part in excess. Where the after part is less than 50 % of the standard no credit shall be given for the excess sheer forward. Where the after sheer is between 50 % and 75 % of the standard, intermediate allowances may be granted for excess sheer forward.

(12)

Where sheer credit is given for a poop or forecastle the following formula shall be used:
S = y L' /3L
where:
s is the sheer credit, to be deducted from the deficiency, or added to the excess of sheer;
y is the difference between actual and standard height of superstructure at the after or forward perpendicular;
L' is the mean enclosed length of poop or forecastle up to a maximum length of 0.5 L; and
L is the length of the ship as defined in regulation 3(1).
The above formula provides a curve in the form of a parabola tangent to the actual sheer curve at the freeboard deck and intersecting the end ordinate at a point below the superstructure deck a distance equal to the standard height of a superstructure. The superstructure deck shall not be less than standard height above this curve at any point. This curve shall be used in determining the sheer profile for forward and after halves of the ship.

(13)

(a)
Any excess in the height of a superstructure which does not extend to the after perpendicular cannot be regarded as contributing to the sheer allowance.
(b)
Where the height of a superstructure is less than standard, the superstructure deck shall not be less than the minimum height of the superstructure above the virtual shear curve at any point. For this purpose y shall be taken as the difference between the actual and minimum height of the superstructure at the after/forward perpendicular
(c)
For a raised quarterdeck credit may be given only when the height of this quarterdeck is greater than the standard height of' “other superstructures” as defined in regulation 33, and only for the amount by which the actual height of the raised quarterdeck exceeds that standard height.
(d)
When a poop or a forecastle has sloping end bulkheads, the sheer credit may be allowed on account of excess height. The formula given in paragraph (12) shall be used, the values for y and L' being as shown in figure 38.3
Figure 38.3 Sheer credit S for excess height

(14)

The correction for sheer shall be the deficiency or excess of sheer (see paragraphs (9) to (11) inclusive), multiplied by
0.75 – S1/2L
Where
S1 is the total length S of enclosed superstructures as defined in regulation 34 without trunks.

(15)

Where the sheer is less than the standard, the correction for deficiency in sheer (see paragraph (14)) shall be added to the freeboard.

(16)

In ships where an enclosed superstructure covers 0.1L before and 0.1L abaft amidships, the correction for excess of sheer as calculated under the provisions of paragraph (14) shall be deducted from the freeboard; in ships where no enclosed superstructure covers amidships, no deduction shall be made from the freeboard; where an enclosed superstructure covers less than 0.1L before and 0.1L abaft amidships, the deduction shall be obtained by linear interpolation. The maximum deduction for excess sheer shall be at the rate of 125 mm per 100 m of length.
In applying this paragraph, the height of the superstructure shall be related to its standard height. Where the height of the superstructure or raised quarterdeck is less than standard, the reduction shall be in the ratio of the actual to the standard height thereof.

Regulation 39 Minimum bow height and reserve buoyancy

(1)

The bow height (Fb), defined as the vertical distance at the forward perpendicular between the waterline corresponding to the assigned summer freeboard and the designed trim and the top of the exposed deck at side, shall be not less than:
Fb = [6075(L/100) – 1875(L/100)² + 200(L/100)ü]” [2.08 + 0609Cb – 1603Cwf – 0.0129(L/d1)]
where:
Fb is the calculated minimum bow height, in mm;
L is the length, as defined in regulation 3, in m;
B is the moulded breadth, as defined in regulation 3, in m;
d1 is the draught at 85 % of the least moulded depth, in metres;
Cb is the block coefficient, as defined in regulation 3;
Cwf is the waterplane area coefficient forward of L/2:
Cwf = Awf/{(L/2)·B};
Awf is the waterplane area forward of L/2 at draught d1, in m2.
For ships to which timber freeboards are assigned, the summer freeboard (and not the timber summer freeboard) is to be assumed when applying paragraph (1).

(2)

Where the bow height required in paragraph (1) is obtained by sheer, the sheer shall extend for at least 15 % of the length of the ship measured from the forward perpendicular. Where it is obtained by fitting a superstructure, such superstructure shall extend from the stem to a point at least 0.07L abaft the forward perpendicular, and shall be enclosed as defined in regulation 3(10).

(3)

Ships which, to suit exceptional operational requirements, cannot meet the requirements of paragraphs (1) and (2) of this regulation may be given special consideration by the Administration.

(4)

(a)
The sheer of the forecastle deck may be taken into account, even if the length of the forecastle is less than 0.15L, but greater than 0.07L, provided that the forecastle height is not less than one half of standard height of superstructure as defined in regulation 33 between 0.07L and the forward perpendicular.
(b)
Where the forecastle height is less than one half of the standard height of superstructure, as defined in regulation 33, the credited bow height may be determined as follows:
(i)
Where the freeboard deck has sheer extending from abaft 0.15L, by a parabolic curve having its origin at 0.15L abaft the forward perpendicular at a height equal to the midship depth of the ship, extended through the point of intersection of forecastle bulkhead and deck, and up to a point at the forward perpendicular not higher than the level of the forecastle deck (as illustrated in figure 39.1). However, if the value of the height denoted ht in figure 39.1 is smaller than the value of the height denoted hb then ht may be replaced by hb in the available bow height.
Where:
(ii)
Where the freeboard deck has sheer extending for less than 0.15L or has no sheer, by a line from the forecastle deck at side at 0.07L extended parallel to the base line to the forward perpendicular (as illustrated in figure 39.2).
Where:
hf = Half standard height of superstructure as defined in regulation 33.

(5)

All ships assigned a type “B” freeboard, other than oil tankers, chemical tankers and gas carriers, shall have additional reserve buoyancy in the fore end. Within the range of 0.15L abaft of the forward perpendicular, the sum of the projected area between the summer load waterline and the deck at side (A1 and A2 in figure 39.3) and the projected area of an enclosed superstructure, if fitted, (A3) shall not be less than:
[0.15·Fmin+ 4·(L/3 + 10)]·L/1000 (m²),
where:
Fmin is calculated by: Fmin = (F0 · f1) + f2;
F0 is the tabular freeboard, in mm, taken from table 28.2, corrected for regulation 27(9) or 27(10), as applicable;
f1 is the correction for block coefficient given in regulation 30; and
f2 is the correction for depth, in mm, given in regulation 31.

Regulation 40 Minimum freeboards

(1)

The minimum freeboard in summer shall be the freeboard derived from the tables in regulation 28, as modified by the corrections in regulations 27, as applicable, 29, 30, 31, 32, 37, 38 and, if applicable, 39.

(2)

The freeboard in salt water, as calculated in accordance with paragraph (1), but without the correction for deck line, as provided by regulation 32, shall not be less than 50 mm. For ships having in position 1 hatchways with covers which do not comply with the requirements of regulation 16(1) through (5) or regulation 26, the freeboard shall be not less than 150 mm.

(3)

The minimum freeboard in the Tropical Zone shall be the freeboard obtained by a deduction from the summer freeboard of one forty-eighth of the summer draught measured from the top of the keel to the centre of the ring of the load line mark.

(4)

The freeboard in salt water, as calculated in accordance with paragraph (3), but without the correction for deck line, as provided by regulation 32, shall not be less than 50 mm. For ships having in position 1 hatchways with covers which do not comply with the requirements of regulation 16(1) through (5) or regulation 26, the freeboard shall be not less than 150 mm.

(5)

The minimum freeboard in winter shall be the freeboard obtained by an addition to the summer freeboard of one forty-eighth of summer draught, measured from the top of the keel to the centre of the ring of the load line mark.

(6)

The minimum freeboard for ships of not more than 100 m in length which enter any part of the North Atlantic defined in regulation 52 (Annex II) during the winter seasonal period shall be the winter freeboard plus 50 mm. For other ships, the winter North Atlantic freeboard shall be the winter freeboard.

(7)

The minimum freeboard in fresh water of unit density shall be obtained by deducting from the minimum freeboard in salt water:
Δ/(40·T) (cm)
where:
Δ is the displacement in salt water in tonnes at the summer load waterline; and T is the tonnes per centimetre immersion in salt water at the summer load waterline.

(8)

Where the displacement at the summer load waterline cannot be certified, the deduction shall be one forty-eight of summer draught, measured from the top of the keel to the centre of the ring of the load line mark.