Merchant Shipping (Safety) (Subdivision and Damage Stability of Cargo Ships) Regulation
(Cap. 369, sections 96, 107 and 112A)
(Enacting provision omitted—E.R. 2 of 2020)
[3 July 1992]
(Format changes—E.R. 2 of 2020)
In this Regulation, unless the context otherwise requires—
aft terminal (後端點) means the aft limit of the subdivision length; breadth (B) (船寬(B)) means the greatest moulded breadth of the ship at or below the deepest subdivision load line; Certifying Authority (核證當局) has the meaning assigned to it in the Merchant Shipping (Safety) (Cargo Ship Construction and Survey) (Ships Built On or After 1 September 1984) Regulations (Cap. 369 sub. leg. S); (E.R. 2 of 2020) deepest subdivision load line (最深分艙載重線) means the subdivision load line which corresponds to the summer draught to be assigned to the ship in accordance with the Merchant Shipping (Safety) (Load Line) Regulations (Cap. 369 sub. leg. AD); (E.R. 2 of 2020) draught (d) (吃水(d)) in relation to any waterline means the vertical distance from the moulded baseline at mid-length to that waterline; forward terminal (前端點) means the forward limit of the subdivision length; freeboard deck (乾舷甲板) has the meaning assigned to it in the Merchant Shipping (Safety) (Load Line) Regulations (Cap. 369 sub. leg. AD); (E.R. 2 of 2020) mid-length (船長度中點) means the mid-point of the subdivision length of the ship; partial load line (部分載重線) means the light ship draught plus 60% of the difference between the light ship draught and the deepest subdivision load line; permeability (μ) (滲透率(μ)) in relation to a space means the proportion of the immersed volume of that space which can be occupied by water; subdivision length (LS) (分艙長度(LS)) means the greatest projected moulded length of that part of the ship at or below deck or decks limiting the vertical extent of flooding with the ship at the deepest subdivision load line; subdivision load line (分艙載重線) means a waterline used in determining the subdivision of the ship in accordance with this Regulation; watertight (水密) in relation to any structure means, capable of preventing the passage of water, through the structure in any direction under the maximum head of water which such structure might have to sustain in the event of damage to the ship but for structures below the freeboard deck at least the head of water up to the freeboard deck.Subject to subsection (2), this Regulation shall apply to any seagoing cargo ship registered in Hong Kong which is—
over 100 metres in subdivision length and constructed on or after 1 February 1992 and before 1 January 2009; and
80 metres in subdivision length and upwards but not exceeding 100 metres in subdivision length and constructed on or after 1 July 1998 and before 1 January 2009. (L.N. 99 of 1999; L.N. 258 of 2018)
This Regulation shall not apply to a ship which conforms to the requirements relating to subdivision and damage stability specified in—
Annex 1 to the International Convention for the Prevention of Pollution from Ships 1973 as amended by the Protocol of 1978;
International Bulk Chemical Code (Resolution MSC 4(48) and MSC 10(54));
International Gas Carrier Code (Resolution MSC 5(48));
Guidelines for the Design and Construction of Offshore Supply Vessels (Resolution A.469(XII));
Code of Safety for Special Purpose Ships (Resolution A.534(13)); or
regulation 27 of the 1966 Load Line Convention for bulk carriers assigned B-60 or B-100 freeboards.
The Director may, subject to such terms (if any) as he may specify, exempt any ship or any class of ship from the application of any specified provision of this Regulation.
Every ship shall be subdivided by watertight bulkheads into compartments to provide the ship with subdivision and damage stability of a standard which shall not be less than the required subdivision index “R” calculated in accordance with the Schedule.
If subsection (1) is contravened in relation to a ship, the owner of the ship commits an offence and is liable to a fine at level 3. (L.N. 258 of 2018)
There shall be supplied to the master of the ship such reliable information as is necessary to enable him by rapid and simple means to obtain accurate guidance as to the stability of the ship under varying conditions of service. The information shall include—
a curve of minimum operational metacentric height (GM) versus draught which assures compliance with the relevant intact stability requirements in the Merchant Shipping (Safety) (Load Line) Regulations (Cap. 369 sub. leg. AD) and the requirements in the Schedule, alternatively a corresponding curve of the maximum allowable vertical centre of gravity (KG) versus draught, or with the equivalents of either of these curves; (L.N. 52 of 2018; E.R. 2 of 2020)
instructions concerning the operation of cross-flooding arrangements; and
all other data and aids which might be necessary to maintain stability after damage.
There shall be permanently exhibited, or readily available on the navigating bridge, for the guidance of the officer in charge of the ship, plans showing clearly for each deck and hold the boundaries of the watertight compartments, the openings therein with the means of closure and position of any controls thereof, and the arrangements for the correction of any list due to flooding. In addition, booklets containing the aforementioned information shall be made available by the owner of the ship for the use of the officers of the ship.
In providing the information referred to in subsection (1)(a) and determining the GM or KG values—
in the case where intact stability requirements are more onerous than the values referred to in paragraph (b), such requirements shall apply;
in the case where values determined from considerations solely related to the subdivision index are more onerous than such intact stability requirements—
the limiting GM values shall be varied linearly between the deepest subdivision load line and the partial load line; and
for draughts below the partial load line, the GM value shall be assumed constant; and
in the case where values determined from both intact stability requirements and the subdivision index apply—
the limiting GM shall be varied linearly between the deepest subdivision load line and the partial load line; and
for draughts below the partial load line, where the subdivision index is more onerous, the GM value shall be assumed constant and where the intact stability requirements are more onerous, such requirements shall apply.
If subsection (1) or (2) is contravened in relation to a ship, the owner of the ship commits an offence and is liable to a fine at level 3. (L.N. 258 of 2018)
The number of openings in watertight subdivisions shall be kept to a minimum compatible with the design and proper working of the ship. Where penetrations of watertight bulkheads and internal decks are necessary for access, piping, ventilation, electrical cables, etc., arrangements shall be made to maintain the watertight integrity. The Certifying Authority may permit relaxation in the watertightness of openings above the freeboard deck, provided that it is demonstrated that any progressive flooding can be easily controlled and that the safety of the ship is not impaired.
Doors provided to ensure the watertight integrity of internal openings which are used while at sea shall be of the sliding watertight type and capable of being remotely closed from the bridge and also capable of being operated locally from each side of the bulkhead. Indicators shall be provided at the control position showing whether the doors are open or closed, and an audible alarm shall be provided at the door closure. The power, control and indicators shall be operable in the event of main power failure. Particular attention is to be paid to minimizing the effect of control system failure. Each power-operated sliding watertight door shall be provided with an individual hand-operated mechanism. It shall be possible to open and close the door by hand at the door itself from both sides.
Access doors and access hatch covers normally closed at sea, intended to ensure the watertight integrity of internal openings, shall be provided with means of indication locally and on the bridge showing whether these doors or hatch covers are open or closed. A notice shall be affixed to each such door or hatch cover to the effect that it is not to be left open. The use of such doors and hatch covers shall be authorized by the officer of the watch.
Watertight doors or ramps of satisfactory construction may be fitted to internally subdivide large cargo spaces, provided that the Certifying Authority is satisfied that such doors or ramps are essential. These doors or ramps may be hinged, rolling or sliding doors or ramps, but shall not be remotely controlled. Such doors or ramps shall be closed before the voyage commences and shall be kept closed during navigation; the time of opening such doors or ramps in port and of closing them before the ship leaves port shall be entered in the log book. Should any of the doors or ramps be accessible during the voyage, they shall be fitted with a device which prevents unauthorized opening.
Other closing appliances which are kept permanently closed at sea to ensure the watertight integrity of internal openings shall be provided with a notice which is to be affixed to each such closing appliance to the effect that it is to be kept closed. Manholes fitted with closely bolted covers need not be so marked.
If subsection (1), (2), (3), (4) or (5) is contravened in relation to a ship, the owner and the master of the ship each commits an offence and is liable to a fine at level 3. (L.N. 258 of 2018)
All external openings leading to compartments assumed intact in the damage analysis, which are below the final damage waterline, shall be watertight.
External openings required to be watertight in accordance with subsection (1) shall be of sufficient strength and, except for cargo hatch covers, shall be fitted with indicators on the bridge.
Openings in the shell plating below the deck limiting the vertical extent of damage shall be kept permanently closed while at sea. Should any of these openings be accessible during the voyage, they shall be fitted with a device which prevents unauthorized opening.
Notwithstanding the requirements of subsection (3), the Certifying Authority may authorize that particular doors may be opened at the discretion of the master, if necessary for the operation of the ship and provided that the safety of the ship is not impaired.
Other closing appliances which are kept permanently closed at sea to ensure the watertight integrity of external openings shall be provided with a notice affixed to each appliance to the effect that it is to be kept closed. Manholes fitted with closely bolted covers need not be so marked.
If subsection (1), (2), (3) or (5) is contravened in relation to a ship, the owner and the master of the ship each commits an offence and is liable to a fine at level 3. (L.N. 258 of 2018)
A surveyor carrying out a survey of a ship for the purpose of issuing a cargo ship safety construction certificate shall, before issuing such certificate, satisfy himself that the requirements in this Regulation have been complied with to an extent which is satisfactory having regard to the service for which the ship is intended and the period for which the certificate is to be issued.
Every ship shall be maintained in such condition so as to conform to this Regulation and the structure of the ship shall not be altered in any manner without the approval of the Certifying Authority.
If subsection (1) is contravened in relation to a ship, the owner and the master of the ship each commits an offence and is liable to a fine at level 3. (L.N. 258 of 2018)
Where this Regulation requires the compliance with a particular requirement, the Director may, in relation to a particular ship or a class of ships, accept or permit an alternative arrangement as compliance with such requirement, where he is satisfied by trial or otherwise, that such arrangement is at least as effective for the purpose of ensuring the safety of the ship as compliance with such requirement would have been.
The Director may—
by notice published in the Gazette amend the Schedule; and
issue instructions, directions or codes of practice providing practical guidance with respect to specifications, standards or requirements specified in this Regulation.
This Schedule is intended to provide ships with a minimum standard of subdivision.
The degree of subdivision to be provided shall be determined by the required subdivision index “R”, as follows—
for ships over 100 metres in Ls:
R = (0.002 + 0.0009Ls)1/3,
where “Ls” is in metres; and
for ships of 80 metres in Ls and upwards but not exceeding 100 metres in Ls:
| R = 1 − [1/(1 + | Ls | ． | Ro | )], |
| 100 | 1 Ro |
The attained subdivision index “A”, calculated in accordance with this Part, shall not be less than the required subdivision index “R”, calculated in accordance with Part I.
The attained subdivision index “A” shall be calculated for the ship by the following formula—
A = Σ pi si
where—
| “i” | represents each compartment or group of compartments under consideration; | |
| “pi” | accounts for the probability that only the compartment or group of compartments under consideration may be flooded, disregarding any horizontal subdivision; | |
| “si” | accounts for the probability of survival after flooding the compartment or group of compartments under consideration, including the effects of any horizontal subdivision. | |
In calculating “A”, level trim shall be used.
This summation covers only those cases of flooding which contribute to the value of the attained subdivision index “A”.
The summation indicated by the above formula shall be taken over the ship’s length for all cases of flooding in which a single compartment or 2 or more adjacent compartments are involved.
Wherever wing compartments are fitted, contribution to the summation indicated by the formula shall be taken for all cases of flooding in which wing compartments are involved, and additionally, for all cases of simultaneous flooding of a wing compartment or compartments and the adjacent inboard compartment or compartments, assuming a rectangular penetration which extends to the ship’s centreline, but excludes damage to any centreline bulkhead.
The assumed vertical extent of damage is to extend from the baseline upwards to any watertight horizontal subdivision above the waterline or higher. However, if a lesser extent will give a more severe result, such extent is to be assumed.
If pipes, ducts or tunnels are situated within assumed flooded compartments, arrangements are to be made to ensure that progressive flooding cannot thereby extend to compartments other than those assumed flooded. However, the Certifying Authority may permit minor progressive flooding if it is demonstrated that its effects can be easily controlled and the safety of the ship is not impaired.
In the flooding calculations carried out according to this Schedule, only one breach of the hull need be assumed.
The factor “pi” shall be calculated according to paragraph 1.1 as appropriate, using the following notations—
| x1 | = | the distance from the aft terminal of “Ls” to the foremost portion of the aft end of the compartment being considered; |
| x2 | = | the distance from the aft terminal of “Ls” to the aftermost portion of the forward end of the compartment being considered; |
| E1 | = | x1/Ls |
| E2 | = | x2/Ls |
| E | = | E1 + E2 − 1 |
| J | = | E2 − E1 |
| J’ | = | J − E, if E ≥ 0 |
| J’ | = | J + E, if E ＜ 0 |
| The maximum nondimensional damage length | ||
| Jmax | = | 48/Ls, but not more than 0.24. |
| The assumed distribution density of damage location along the ship’s length | ||
| a | = | 1.2 + 0.8E, but not more than 1.2. |
| The assumed distribution function of damage location along the ship’s length | ||
| F | = | 0.4 + 0.25E (1.2 + a) |
| y | = | J/Jmax |
| p | = | F1Jmax |
| q | = | 0.4F2 (Jmax)2 |
| F1 | = | y2 − y3/3, if y ＜ 1, |
| F1 | = | y − 1/3 otherwise; |
| F2 | = | y3/3 − y4/12, if y ＜ 1, |
| F2 | = | y2/2 − y/3 + 1/12 otherwise. |
The factor “pi” is determined for each single compartment.
Where the compartment considered extends over the entire ship length, “Ls”—
pi = 1
Where the aft limit of the compartment considered coincides with the aft terminal—
pi = F + 0.5ap + q
Where the forward limit of the compartment considered coincides with the forward terminal—
pi = 1 F + 0.5ap
When both ends of the compartment considered are inside the aft and forward terminals of the ship length, “Ls”—
pi = ap
In applying the formulae of paragraphs 1.1.2, 1.1.3 and 1.1.4, where the compartment considered extends over the “mid-length”, these formulae values shall be reduced by an amount determined according to the formula for “q”, in which “F2” is calculated taking “y” to be J’/Jmax.
Wherever wing compartments are fitted, the “pi” value for a wing compartment shall be obtained by multiplying the value, as determined in paragraph 3, by the reduction factor “r” according to paragraph 2.2, which represents the probability that the inboard spaces will not be flooded.
The “pi” value for the case of simultaneous flooding of a wing and adjacent inboard compartment shall be obtained by using the formulae of paragraph 3, multiplied by the factor (1 r).
The reduction factor “r” shall be determined by the following formulae—
For J ≥ 0.2 b/B—
| r | = | b | (2.3 + | 0.08 | ) + 0.1, if b/B ≤ 0.2 |
| B | J + 0.02 |
| r | = ( | 0.016 | + | b | + 0.36 | ), if b/B ＞ 0.2 |
| J + 0.02 | B |
For J ＜ 0.2 b/B the reduction factor “r” shall be determined by linear interpolation between—
| r | = | 1, for J = 0; and |
| r | = | as for the case where J ≥ 0.2b/B, for J = 0.2b/B, |
where—
| b | = | the mean transverse distance in metres measured at right angles to the centreline at the deepest subdivision load line between the shell and a plane through the outermost portion of and parallel to that part of the longitudinal bulkhead which extends between the longitudinal limits used in calculating the factor “pi”. |
To evaluate “pi” for compartments taken singly the formulae in paragraphs 1 and 2 shall be applied directly.
To evaluate the “pi” values attributable to groups of compartments the following applies—
for compartments taken by pairs—
| pi | = | p12 − p1 − p2 |
| pi | = | p23 − p2 − p3, etc. |
for compartments taken by groups of 3—
| pi | = | p123 − p12 − p23 + p2 |
| pi | = | p234 − p23 − p34 + p3, etc. |
for compartments taken by groups of 4—
| pi | = | p1234 − p123 − p234 + p23 |
| pi | = | p2345 − p234 − p345 + p34, etc. |
where—
| p12, p23, p34, etc.; | ||
| p123, p234, p345, etc.; and | ||
| p1234, p2345, p3456, etc., |
shall be calculated according to the formulae in paragraphs 1 and 2 for a single compartment whose nondimensional length “J” corresponds to that of a group consisting of the compartments indicated by the indices assigned to “p”.
The factor “pi” for a group of 3 or more adjacent compartments equals zero if the nondimensional length of such a group minus the nondimensional length of the aftermost and foremost compartments in the group is greater than “Jmax”.
The factor “si” shall be determined for each compartment or group of compartments according to the following—
In general for any condition of flooding from any initial loading condition “s” shall be—
| s | = | C 0.5(GZ max )(range) |
with—
| C | = | 1, if θe ≤ 25°; |
| C | = | 0, if θe ＞ 30°; |
| C | = | (30 − θe)/5, otherwise; |
| GZmax | = | maximum positive righting lever (in metres) within the range as given below but not more than 0.1 m; |
| range | = | range of positive righting levers beyond the angle of equilibrium (in degrees) but not more than 20°, however the range shall be terminated at the angle where openings not capable of being closed weathertight are immersed; |
| θe | = | final equilibrium angle of heel (in degrees). |
s = 0, where the final waterline taking into account sinkage, heel and trim, immerses the lower edge of openings through which progressive flooding may take place. Such openings shall include air-pipes, ventilators, and openings which are closed by means of weathertight doors or hatch covers, and may exclude those openings closed by means of watertight manhole covers and flush scuttles, small watertight hatch covers which maintain the high integrity of the deck, remotely operated sliding watertight doors, access doors, and access hatch covers, of watertight integrity, normally closed at sea and sidescuttles of the non-opening type. However, if the compartments so flooded are taken into account in the calculations the requirements of this Part shall be applied.
For each compartment or group of compartments “si” shall be weighted according to draught considerations as follows—
si = 0.5s1 + 0.5sp
where—
s1 is the “s” factor at the deepest subdivision load line;
“sp” is the “s” factor at the partial load line.
For all compartments forward of the collision bulkhead, the “s” value, calculated assuming the ship to be at its deepest subdivision load line and with assumed unlimited vertical extent of damage, is to be equal to 1.
Wherever a horizontal subdivision is fitted above the waterline in question the following applies.
The “s” value for the lower compartment or group of compartments shall be obtained by multiplying the value as determined in paragraph 1.1 by the reduction factor “v” according to paragraph 3.3, which represents the probability that the spaces above the horizontal subdivision will not be flooded.
In cases of positive contribution to index “A” due to simultaneous flooding of the spaces above the horizontal subdivision, the resulting “s” value for such a compartment or group of compartments shall be obtained by an increase of the value as determined by paragraph 3.1 by the “s” value for simultaneous flooding according to paragraph 1.1, multiplied by the factor (1 v).
The probability factor “vi” shall be calculated according to—
| vi | = | H d | ||
| Hmax − d | for the assumed flooding up to the horizontal subdivision above the subdivision load line, where “H” is to be restricted to a height of “Hmax”; | |||
| vi | = | 1, | if the uppermost horizontal subdivision in way of the assumed damaged region is below “Hmax”, | |
| where— | ||||
| H | is the height of the horizontal subdivision above the baseline (in metres) which is assumed to limit the vertical extent of damage; | |||
| Hmax | is the maximum possible vertical extent of damage above the baseline (in metres); or | |||
| Hmax | = d + 0.056Ls (1 − Ls/500), | |||
| if Ls ≤ 250 m; | ||||
| Hmax | = d + 7, if Ls ＞ 250 m, | |||
| whichever is less. | ||||
For the purpose of the subdivision and damage stability calculations of this Regulation, the permeability of each space or part of a space shall be as follows—
| Space | Permeability |
| Appropriated to stores | 0.60 |
| Occupied by accommodation | 0.95 |
| Occupied by machinery | 0.85 |
| Void spaces | 0.95 |
| Dry cargo spaces | 0.70 |
| Intended for liquid | 0 or 0.95* |
* whichever results in the more severe requirements.