In order to use this Part of the Code, compliance with regulation 6 and 7 of SOLAS
II-1 Part B-1 shall be confirmed to be impracticable for the vessel arrangement
due to its size. This shall be in the form of a statement from the Naval
Architect following consideration that SOLAS II-1 PART B-1 was not developed for
vessels of this size.
4.25 Floodable Length
(1) The floodable length at any point shall be determined by a method of
calculation which takes into consideration the form, draught and other
characteristics of the ship in question.
(2) In a ship with a continuous bulkhead deck, the floodable length at a given
point is the maximum portion of the length of the ship, having its centre at the
point in question, which can be flooded under the definite assumptions set forth
in section 4.26 without the ship being submerged beyond the margin line.
(3) In the case of a ship not having a continuous bulkhead deck, the floodable
length at any point may be determined to an assumed continuous margin line which
at no point is less than 76 millimetres below the top of the deck (at side) to
which the bulkheads concerned and the shell are carried watertight.
(4) Where a portion of an assumed margin line is appreciably below the deck to
which bulkheads are carried, the Administration may permit a limited relaxation
in the watertightness of those portions of the bulkheads which are above the
margin line and immediately under the higher deck.
4.26 Permeability
(1) The definite assumptions referred to in section 4.25 relate to the
permeability of the spaces below the margin line.
(2) In determining the floodable length, a uniform average permeability shall be
used throughout the whole length of each of the following portions of the ship
below the margin line-
(3) The uniform average permeability throughout the machinery room shall be
determined from the formula-
-
where-
- a = the volume of the passenger spaces;
- c = the volume of between-deck spaces below the margin line within the limits
of the machinery room which are appropriated to stores; and
- v = the whole volume of the machinery room below the margin line.
(4) Where it is shown to the satisfaction of the Administration that the average
permeability as determined by detailed calculation is less than that given by
the formula, the detailed calculated value may be used and for the purpose of
such calculation, the permeability of passenger spaces shall be taken as 95,
that of all store spaces as 60, and that of double bottom, oil fuel and other
tanks at such value as may be approved in each case.
(5) Except as provided in Section (6), the uniform average permeability throughout
the portion of the ship forward of or abaft the machinery room shall be
determined from the formula-
where-
(6) In the case of unusual arrangements the Administration may allow, or require,
a detailed calculation of average permeability for the portions forward of or
abaft the machinery room and for the purpose of such calculation, the
permeability of passenger spaces shall be taken as 95, that of spaces containing
machinery as 85, that of all store spaces as 60, and that of double bottom, oil
fuel and other tanks at such value as may be approved in each case.
(7) Where a between-deck compartment between two watertight transverse bulkheads
contains any passenger or crew space, the whole of that compartment, less any
space completely enclosed within permanent steel bulkheads and appropriated to
other purposes, shall be regarded as passenger space.
4.27 Permissible Length of Compartments
General
(1) Ships shall be as efficiently subdivided as is possible having regard to the
nature of the service for which they are intended and the degree of subdivision
shall vary with the length of the ship and with the service, in such manner that
the highest degree of subdivision corresponds with the ships of greatest length,
primarily engaged in the carriage of passengers.
Factor of subdivision
(2) The maximum permissible length of a compartment having its centre at any point
in the ship's length is obtained from the floodable length by multiplying the
latter by an appropriate factor called the factor of subdivision.
(3) The factor of subdivision shall depend on the length of the ship, and for a
given length shall vary according to the nature of the service for which the
ship is intended and it shall decrease in a regular and continuous manner-
-
(a) as the length of the ship increases, and
-
(b) from a factor A, to a factor B.
(4) The variations of the factors A and B shall be expressed by the following
formulae (1) and (2) where L is the length of the ship as defined in Chapter 2-
(Where L = 131 metres and above)
|
(1)
|
(Where L = 79 metres and above)
|
(2)
|
Criterion of Service
(5) For a ship of given length the appropriate factor of subdivision shall be
determined by the criterion of service numeral (hereinafter called the criterion
numeral) as given by the following formulae (3) and (4) where-
-
Cs = the criterion numeral;
-
L = the length of the ship (metres), as defined in Chapter
2;
-
M = the volume of the machinery room (cubic metres), as defined in Chapter
2, with the addition thereto of the volume of any permanent
oil fuel bunkers which may be situated above the inner bottom and
forward of or abaft the machinery room;
-
P = the whole volume of the passenger spaces below the margin line (cubic
metres), as defined in Chapter
2;
-
V = the whole volume of the ship below the margin line (cubic metres); and
-
P1 = KN
-
where:
| when P1 is greater than
P-
|
|
|
(3)
|
| in other cases-
|
|
|
(4)
|
(6) Where the value of KN is greater than the sum of P and the whole
volume of the actual passenger spaces above the margin line, the figure to be
taken as P1 is that sum or two-thirds KN , whichever is
the greater.
(7) For ships not having a continuous bulkhead deck the volumes shall be taken up
to the actual margin lines used in determining the floodable lengths.
Rules for Subdivision of Ships other than those covered by Section (14) (Special
Subdivision Standards)
(8) The subdivision abaft the forepeak of ships of 131 metres in length and
upwards having a criterion numeral of 23 or less shall be governed by the factor
A given by formula (1); of those having a criterion numeral of 123 or more by
the factor B given by formula (2); and of those having a criterion numeral
between 23 and 123 by the factor F obtained by linear interpolation between the
factors A and B, using the formula-
|
(5)
|
(9) Nevertheless, where the criterion numeral is equal to 45 or more and
simultaneously the computed factor of subdivision as given by formula (5) is
0.65 or less, but more than 0.5, the subdivision abaft the forepeak shall be
governed by the factor 0.5.
(10) Where the factor F is less than 0.4 and it is shown to the satisfaction of
the Administration to be impracticable to comply with the factor F in a
machinery compartment of the ship, the subdivision of such compartment may be
governed by an increased factor, which, however, shall not exceed 0.4.
(11) The subdivision abaft the forepeak of ships of less than 131 metres but not
less than 79 metres in length having a criterion numeral equal to S, where-
shall be governed by the factor unity; of those having a criterion numeral of 123
or more by the factor B given by the formula (2); of those having a criterion
numeral between S and 123 by the factor F obtained by linear interpolation
between unity and the factor B using the formula-
|
(6)
|
(12) The subdivision abaft the forepeak of ships of less than 131 metres but not
less than 79 metres in length and having a criterion numeral less than S , and
of ships of less than 79 metres in length shall be governed by the factor unity,
unless, in either case, it is shown to the satisfaction of the Administration to
be impracticable to comply with this factor in any part of the ship, in which
case the Administration may allow such relaxation as may appear to be justified,
having regard to all the circumstances.
(13) The provisions of Section (12) shall apply also to ships of whatever length,
which are certified to carry a number of passengers exceeding 12 but not
exceeding:
or 36, whichever is less.
Special Subdivision Standards for Ships complying with Section 7.21(2)
(14) In the case of ships complying with section 7.21(2) the subdivision abaft the
forepeak shall be governed by a factor of 0.5 or by the factor determined
according to Sections (5) to (13), if less than 0.5.
(15) In the case of such ships of less than 91.5 metres in length, if the
Administration is satisfied that compliance with such factor would be
impracticable in a compartment, it may allow the length of that compartment to
be governed by a higher factor provided the factor used is the lowest that is
practicable and reasonable in the circumstances.
(16) The special provisions regarding permeability given in section 4.26(2) shall
be employed when calculating the floodable length curves.
(17) Where the Administration is satisfied that, having regard to the nature and
conditions of the intended voyages, compliance with the other provisions of this
Chapter and Chapters 6 and 7 is sufficient, the requirements of section 4.27(16)
need not be complied with.
4.28 Special Requirements concerning Subdivision
(1) Where in a portion or portions of a ship the watertight bulkheads are carried
to a higher deck than in the remainder of the ship and it is desired to take
advantage of this higher extension of the bulkheads in calculating the floodable
length, separate margin lines may be used for each such portion of the ship
provided that-
-
(a) the sides of the ship are extended throughout the ship's length to the
deck corresponding to the upper margin line and all openings in the
shell plating below this deck throughout the length of the ship are
treated as being below a margin line, for the purposes of paragraph; and
-
(b) the two compartments adjacent to the "step" in the bulkhead deck are
each within the permissible length corresponding to their respective
margin lines, and, in addition, their combined length does not exceed
twice the permissible length based on the lower margin line.
(2) A compartment may exceed the permissible length determined in accordance with
section 4.27 provided the combined length of each pair of adjacent compartments
to which the compartment in question is common does not exceed either the
floodable length or twice the permissible length, whichever is the less.
(3) If one of the two adjacent compartments is situated inside the machinery room,
and the second is situated outside the machinery room, and the average
permeability of the portion of the ship in which the second is situated differs
from that of the machinery room, the combined length of the two compartments
shall be adjusted to the mean average permeability of the two portions of the
ship in which the compartments are situated.
(4) Where the two adjacent compartments have different factors of subdivision, the
combined length of the two compartments shall be determined proportionately.
(5) In ships of 100 metres in length and upwards, one of the main transverse
bulkheads abaft the forepeak shall be fitted at a distance from the forward
perpendicular which is not greater than the permissible length.
(6) A main transverse bulkhead may be recessed provided that all parts of the
recess lie inboard of vertical surfaces on both sides of the ship, situated at a
distance from the shell plating equal to one fifth the breadth of the ship, as
defined in Chapter 2, and measured at right angles to the centreline at the
level of the deepest subdivision load line. Any part of a recess which lies
outside these limits shall be dealt with as a step in accordance with Section
(7).
(7) A main transverse bulkhead may be stepped provided that it meets one of the
following conditions-
-
(a) the combined length of the two compartments, separated by the bulkhead
in question, does not exceed either 90% of the floodable length or twice
the permissible length, except that, in ships having a factor of
subdivision greater than 0.9, the combined length of the two
compartments in question shall not exceed the permissible length;
-
(b) additional subdivision is provided in way of the step to maintain the
same measure of safety as that secured by a plane bulkhead; and
-
(c) the compartment over which the step extends does not exceed the
permissible length corresponding to a margin line taken 76 millimetres
below the step.
(8) Where a main transverse bulkhead is recessed or stepped, an equivalent plane
bulkhead shall be used in determining the subdivision.
(9) If the distance between two adjacent main transverse bulkheads, or their
equivalent plane bulkheads, or the distance between the transverse planes
passing through the nearest stepped portions of the bulkheads, is less than 3
metres plus 3% of the length of the ship, or 11 metres, whichever is the less,
only one of these bulkheads shall be regarded as forming part of the subdivision
of the ship in accordance with the provisions of section 4.27.
(10) Where a main transverse watertight compartment contains local subdivision and
it can be shown to the satisfaction of the Administration that, after any
assumed side damage extending over a length of 3 metres plus 3% of the length of
the ship, or 11 metres, whichever is the less, the whole volume of the main
compartment shall not be flooded, a proportionate allowance may be made in the
permissible length otherwise required for such compartment and in such a case
the volume of effective buoyancy assumed on the undamaged side shall not be
greater than that assumed on the damaged side.
(11) Where the required factor of subdivision is 0.5 or less, the combined length
of any two adjacent compartments shall not exceed the floodable length.
4.29 Stability in Damaged Condition
(1) Sufficient intact stability shall be provided in all service conditions so as
to enable the ship to withstand the final stage of flooding of any one main
compartment which is required to be within the floodable length.
(2) Where two adjacent main compartments are separated by a bulkhead which is
stepped under the conditions of section 4.28(7)(b) the intact stability shall be
adequate to withstand the flooding of those two adjacent main compartments.
(3) Where the required factor of subdivision is 0.5 or less but more than 0.33
intact stability shall be adequate to withstand the flooding of any two adjacent
main compartments.
(4) Where the required factor of subdivision is 0.33 or less the intact stability
shall be adequate to withstand the flooding of any three adjacent main
compartments.
(5) The requirements of Sections (1) to (4) shall be determined by calculations
which are in accordance with Sections (11), (12) and (14) respectively and which
take into consideration the proportions and design characteristics of the ship
and the arrangement and configuration of the damaged compartments and in making
these calculations the ship shall be assumed in the worst anticipated service
condition as regards stability.
(6) Where it is proposed to fit decks, inner skins or longitudinal bulkheads of
sufficient tightness to seriously restrict the flow of water, the Administration
shall be satisfied that proper consideration is given to such restrictions in
the calculations.
(7) The stability required in the final condition after damage, and after
equalization where provided, shall be such that the positive residual righting
lever curve shall have a minimum range of 15° beyond the angle of equilibrium
provided that this range may be reduced to a minimum of 10°, in the case where
the area under the righting lever curve is that specified in Section (8),
increased by the ratio-
where the range is expressed in degrees.
(8) The area under the righting lever curve shall be at least 0.015 metre-radians,
measured from the angle of equilibrium to the lesser of-
-
(a) the angle at which progressive flooding occurs; or
-
(b) 22° (measured from the upright) in the case of one-compartment
flooding, or 27° (measured from the upright) in the case of the
simultaneous flooding of two or more adjacent compartments.
(9) A residual righting lever shall be obtained within the range of positive
stability, taking into account the greatest of the following heeling moments-
-
(a) the crowding of all passengers towards one side;
-
(b) the launching of all fully loaded davit-launched survival craft on one
side; and
-
(c) due to wind pressure,
-
as calculated by the formula-
-
provided that in no case is the righting lever to be less than 0.1 metres.
(10) For the purpose of calculating the heeling moments in Section (9), the
following assumptions shall be made-
-
(a) moments due to crowding of passengers allowing-
-
and passengers shall be distributed on available deck areas towards one
side of the ship on the decks where muster stations are located and in
such a way that they produce the most adverse heeling moment;
-
(b) moments due to launching of all fully loaded davit-launched survival
craft on one side under the following conditions;
-
(i) all lifeboats and rescue boats fitted on the side to which
the ship has heeled after having sustained damage shall be
assumed to be swung out fully loaded and ready for lowering;
-
(ii) for lifeboats which are arranged to be launched fully
loaded from the stowed position, the maximum heeling moment
during launching shall be taken;
-
(iii) a fully loaded davit-launched liferaft attached to each
davit on the side to which the ship has heeled after having
sustained damage shall be assumed to be swung out ready for
lowering;
-
(iv) persons not in the life-saving appliances which are swung
out shall not provide either additional heeling or righting
moment; and
-
(v) life-saving appliances on the side of the ship opposite to
the side to which the ship has heeled shall be assumed to be
in a stowed position;
-
(c) moments due to wind pressure where-
-
(i) a wind pressure of 120 N/m2 to be
applied;
-
(ii) the area applicable shall be the projected lateral area of the
ship above the waterline corresponding to the intact condition; and
-
(iii) the moment arm shall be the vertical distance from a point at
one half of the mean draught corresponding to the intact condition
to the centre of gravity of the lateral area;
-
(d) in intermediate stages of flooding, the maximum righting lever shall
be at least 0.05 metres and the range of positive righting levers shall
be at least 7° provided that in all cases, only one breach in the hull
and only one free surface need be assumed.
(11) For the purpose of making damage stability calculations the volume and
surface permeabilities shall be in general as follows-
| Spaces
|
Permeability
|
| Appropriated to stores
|
60
|
| Occupied by accommodation
|
95
|
| Occupied by machinery
|
85
|
| Intended for liquids
|
0 or 95 (whichever results in the more
severe requirements)
|
provided that higher surface permeabilities shall be assumed in respect of spaces
which, in the vicinity of the damage waterplane, contain no substantial quantity
of accommodation or machinery and spaces which are not generally occupied by any
substantial quantity of stores.
(12) The assumed extent of damage shall be as follows-
-
(a) in the longitudinal extent, 3 metres plus 3% of the length (L) of the
ship, or 11 metres, whichever is the less, provided that where the
required factor of subdivision is 0.33 or less the assumed longitudinal
extent of damage shall be increased as necessary so as to include any
two consecutive main transverse watertight bulkheads;
-
(b) in the transverse extent (measured inboard from the ship's side, at
right angles to the centreline at the level of the deepest subdivision
load line) a distance of one fifth of the breadth of the ship, as
defined in Chapter 2; and
-
(c) in the vertical extent: from the base line upwards without limit;
provided that if any damage of lesser extent than that indicated in this paragraph
would result in a more severe condition regarding heel or loss of metacentric
height, such damage shall be assumed in the calculations.
(13) The following provisions apply with respect to unsymmetrical flooding-
-
(a) Such flooding shall be kept to a minimum consistent with efficient
arrangements;
-
(b) where it is necessary to correct large angles of heel, the means
adopted shall, where practicable, be self-acting, but in any case where
controls to cross-flooding fittings are provided they shall be operable
from above the bulkhead deck;
-
(c) the cross-flooding fittings, together with their controls, shall be
acceptable to the Administration;
-
(d) the maximum angle of heel after flooding but before equalisation shall
not exceed 15°;
-
(e) where cross-flooding fittings are required the time for equalisation
shall not exceed 15 minutes; and
-
(f) suitable information concerning the use of cross-flooding
fittings shall be supplied to the master of the shipfootnote.
(14) The final conditions of the ship after damage and, in the case of
unsymmetrical flooding, after equalization measures have been taken shall be as
follows-
-
(a) in the case of symmetrical flooding there shall be a positive residual
metacentric height of at least 50 millimetres as calculated by the
constant displacement method;
-
(b) in the case of unsymmetrical flooding, the angle of heel for
one-compartment flooding shall not exceed 7° and for the simultaneous
flooding of two or more adjacent compartments, a heel of 12° may be
permitted by the Administration; and
-
(c) in no case shall the margin line be submerged in the final stage of
flooding and if it is considered that the margin line may become
submerged during an intermediate stage of flooding, the Administration
may require such investigations and arrangements as it considers
necessary for the safety of the ship.
(15) The master of the ship shall be supplied with the data necessary to maintain
sufficient intact stability under service conditions to enable the ship to
withstand the critical damage ad in the case of ships requiring cross-flooding
the master of the ship shall be informed of the conditions of stability on which
the calculations of heel are based and be warned that excessive heeling might
result should the ship sustain damage when in a less favourable condition.
(16) The data referred to in Section (15) to enable the master to maintain
sufficient intact stability shall include information which indicates the
maximum permissible height of the ship's centre of gravity above keel (KG), or
alternatively the minimum permissible metacentric height (GM), for a range of
draughts or displacements sufficient to include all service conditions and the
information shall show the influence of various trims taking into account the
operational limits
(17) Datum draught marks shall be provided at the bow and stern, port and
starboard, in accordance with the following provisions-
-
(a) they shall be adequate for assessing the condition and trim of the
vessel;
-
(b) the draught marks may be single datum lines;
-
(c) the marks shall be permanent and easily read but need not be of
contrasting colour to the hull;
-
d) the marks need not indicate more than one draught at each position and
shall be above, but within 1000 millimetres, of the deepest load
waterline; and
-
(e) in the case where the draught marks are not located where they are
easily readable or operational constraints for a particular trade make
it difficult to read the draft marks, then the ship shall also be fitted
with a reliable draught indicating system by which the bow and stern
draughts can be determined.
(18) The draught to which marks relate shall be indicated either above the mark on
the hull and/or in the stability information booklet for the vessel and the
position of the marks shall be verified at initial placement by the
Administration or the vessel’s Assigning Authority.
(19) Where a reliable draught indicating system is fitted as required by Section
(17) consideration shall be given to dispensing with the provision of draught
marks.
(20) On completion of loading of the ship and prior to its departure, the master
shall determine the ship's trim and stability and also ascertain and record that
the ship is in compliance with the approved stability criteria and the
determination of the ship's stability shall always be made by calculation,
provided that the Administration may accept the use of an electronic loading and
stability computer or equivalent means for this purpose.
(21) No relaxation from the requirements for damage stability may be considered by
the Administration unless it is shown that the intact metacentric height in any
service condition necessary to meet these requirements is excessive for the
service intended.
(22) Relaxations from the requirements for damage stability shall be permitted
only in exceptional cases and subject to the condition that the Administration
shall be satisfied that the proportions, arrangements and other characteristics
of the ship are the most favourable to stability after damage which can
practically and reasonably be adopted in the particular circumstances.