Section 2 - Ship Survival Capability and Location of Cargo Tanks 2-1

Section 2

Ship Survival Capability and Location of Cargo Tanks

2.1 General of progressively lesser hazards. Accordingly, a Type 1G

ship shall survive the most severe standard of damage and
2.1.1 Ships subject to the Code should survive the normal its cargo tanks should be located at the maximum prescribed
effects of flooding following assumed hull damage caused distance inboard from the shell plating.
by some external force. In addition, to safeguard the ship
and the environment, the cargo tanks should be protected 2.1.3 The ship type required for individual products is
from penetration in the case of minor damage to the ship indicated in column "c" in the table of Section 19.
resulting, for example, from contact with a jetty or tug, and
given a measure of protection from damage in the case of 2.1.4 If a ship is intended to carry more than one product
collision or stranding, by locating them at specified minimum listed in Section 19, the standard of damage should
distances inboard from the ship's shell plating. Both the correspond to that product having the most stringent ship
damage to be assumed and the proximity of the cargo tanks type requirement. The requirements for the location of
to the ship's shell should be dependent upon the degree of individual cargo tanks, however, are those for ship types
hazard considered to be presented by the product to be related to the respective products intended to be carried.
carried.
2.2 Freeboard and stability
Guidance:
2.2.1 Ships subject to the Code may be assigned the
When applying the requirements of this Section attention minimum freeboard permitted by the International
should be given to IMO-document MSC/Circ 406 of Convention on Load Lines, 1966. However, the draught
14.06.1985 "Guidelines for the Uniform Application of the associated with the assignment shall not be greater than
Survival Requirements of the IBC/IGC-Codes". the maximum draught otherwise permitted by the Code.
2.1.2 Ships subject to the Code should be designed to 2.2.2 The stability of the ship in all seagoing conditions
one of the following standards. and during loading and unloading cargo shall be to a
.1 A Type 1G Ship is a gas carrier intended to standard which is acceptable to the Administration.
transport products as indicated in Section 19 which
require maximum preventative measures to 2.2.3 When calculating the effect of free surface of
preclude the escape of such cargo. consumable liquids for loading conditions it shall be
assumed that, for each type of liquid, at least one transverse
.2 A Type 2G Ship is a gas carrier intended to pair or a single center tank has a free surface and the tank
transport products as indicated in Section 19 which or combination of tanks to be taken into account shall be
require significant preventative measures to those where the effect of free surface is the greatest. The
preclude the escape of such cargo. free surface effect in undamaged compartments shall be
calculated by a method acceptable to the Administration.
.3 A Type 2PG Ship is a gas carrier of 150 m in
length (Lc) or less intended to transport products
2.2.4 Solid ballast shall not normally be used in double
as indicated in Section 19 which require significant
bottom spaces in the cargo area. Where, however, because
preventative measures to preclude escape of such
of stability considerations, the fitting of solid ballast in such
cargo, and where the products are carried in
spaces becomes unavoidable, then its disposition should
independent tanks type C designed (see 4.2.4.4)
be governed by the need to ensure that the impact loads
for a MARVS of at least 7 bar gauge and a cargo
resulting from a bottom damage are not directly transmitted
containment system design temperature of –55/C
to the cargo tank structure.
or above. Note that a ship of this description but
over 150 m in length is to be considered a Type
2.2.5 The master of the ship shall be supplied with a
2G ship.
Loading and Stability Information booklet. This booklet
.4 A Type 3G Ship is a gas carrier intended to carry shall contain details of typical service conditions, loading,
products as indicated in Section 19 which require unloading and ballasting operations, provisions for
moderate preventative measures to preclude the evaluating other conditions of loading and a summary of
escape of such cargo. the ship's survival capabilities. In addition, the booklet shall
contain sufficient information to enable the master to load
Thus a Type 1G ship is a gas carrier intended for the and operate the ship in a safe and seaworthy manner.
transportation of products considered to present the greatest
overall hazard and Types 2G/2PG and Type 3G for products 2.3 Shipside discharges below the freeboard deck
2-2 Section 2 - Ship Survival Capability and Location of Cargo Tanks

2.3.1 The provision and control of valves fitted to 2.4 Conditions of loading
discharges led through the shell from spaces below the
freeboard deck or from within the superstructures and Damage survival capability shall be investigated on the
deckhouses on the freeboard deck fitted with weathertight basis of loading information submitted to the Administration
doors shall comply with the requirements of Regulation for all anticipated conditions of loading and variations in
22 of the International Convention on Load Lines 1966, draught and trim. The survival requirements need not be
except that the choice of valves in paragraph (1) shall be applied to the ship when in the ballast condition, provided
limited to: that any cargo retained on board is solely used for cooling,
circulation or fuelling purposes.
.1 one automatic non-return valve with a positive
means of closing from above the freeboard deck,
Guidance
or
Small independent purge tanks on deck need not be taken
.2 where the vertical distance from the summer load
into account in the stability calculations for the ballast
waterline to the inboard end of the discharge pipe
condition.
exceeds 0,01 Lc, two automatic non-return valves
without positive means of closing, provided that
2.5 Damage assumptions
the inboard valve is always accessible for
examination under service conditions, i.e. the valve
2.5.1 The assumed maximum extent of damage shall
is to be situated above the tropical or subdivision
be in accordance with Table 2.1.
load line.
2.5.2 Other damage:
2.3.2 For the purpose of this section "summer load
waterline" and "freeboard deck", have the meanings as .1 If any damage of a lesser extent than the maximum
defined in the International Convention on Load Lines, 1966. specified in 2.5.1 would result in a more severe
condition, such damage should be assumed.
2.3.3 The automatic non-return valves referred to in
.2 Local side damage anywhere in the cargo area
2.3.1.1 and 2.3.1.2 shall be fully effective in preventing
extending inboard 760 mm measured normal to
admission of water into the ship, taking into account the
the hull shell should be considered and transverse
sinkage, trim and heel in survival requirements in 2.9 and
bulkheads should be assumed damaged when also
shall comply with Recognized Standards.
required by the applicable sub-paragraph of 2.8.1.
2.3-0.1 For automatic non-return valves see Rules for
Machinery Installations, Volume III, Section 11.

Table 2.1

2.5.1.1 Side damage

.1.1 Longitudinal extent 1/3 Lc2/3 or 14,5 m whichever is less
.1.2 Transverse extent measured inboard from ship’s side at right angle B/5 or 11,5 m whichever is less
to the center line at the level of the summer load
line
.1.3 Vertical extent from the moulded line of the bottom shell plating upward without limit
at center line
2.5.1.2 Bottom damage
For 0,3 Lc from the forward perpendicular any other part of the ship
of the ship
.2.1 Longitudinal extent 1/3 Lc2/3 or 14,5 m whichever is less 1/3 Lc2/3 or 5 m whichever is less
.2.2 Transverse extent B/6 or 10 m whichever is less B/6 or 5 m whichever is less
.2.3 Vertical extent B/15 or 2 m whichever is less, measured B/15 or 2 m whichever is less, measured
from the moulded line of the bottom shell from the moulded line of the bottom shell
plating at the center line (see 2.6.3). plating at the center line ( see 2.6.3).

2.5.3 Cargo tanks are to be located at the following minimum distance inboard:
 Section 2 - Ship Survival Capability and Location of Cargo Tanks 2-3

2.7 Flooding assumptions

.1 Type 1G ships: from the side shell plating not
less than the transverse extent of damage specified
2.7.1 The requirements of 2.9 shall be confirmed by
in 2.5.1.1.2 and from the moulded line of the
calculations which take into consideration the design
bottom shell plating at center line not less than the
characteristics of the ship; the arrangements configuration
vertical extent of damage specified in 2.5.1.2.3,
and contents of the damaged compartments; the distribution,
and nowhere less than 760 mm from the shell
relative densities and the free surface effects of liquids; and
plating.
the draught and trim for all conditions of loading.
.2 Types 2G/2PG and 3G ships: from the moulded
line of the bottom shell plating at center line not 2.7.2 The permeabilities of spaces assumed to be damaged
less than the vertical extent of damage specified are to be taken as given in Table 2.2.
in 2.5.1.2.3 and nowhere less than 760 mm from
the shell plating. Table 2.2

2.6 Location of cargo tanks Space Permeability

2.6.1 For the purposeof tank location, the vertical extent appropriate to stores 0,60
of damage is to be measured to the inner bottom when
membrane or semi-membrane tanks are used, otherwise occupied by accommodation 0,95
to the bottom of the cargo tanks. The transverse extent of occupied by machinery 0,85
damage is to be measured to the longitudinal bulkhead when
membrane or semi-membrane tanks are used, otherwise voids 0,95
to the side of the cargo tanks (see Fig. 2.1). For internal
intended for consumable liquids 0 to 0,95 1)
insulation tanks the extent of damage is to be measured
to the supporting tank plating. intended for other liquids 0 to 0,05 1)
1)
The permeability of partially filled compartments shall be consistent
2.6.2 Except for Type 1G ships suction wells installed with the amount of liquid carried in the compartment.
in cargo tanks may protrude into the vertical extent of bottom
damage specified in 2.5.1.2.3 provided that such wells are
as small as practicable and that the protrusion below the
2.7.3 Wherever damage penetrates a tank containing
inner bottom plating does not exceed 25% of the depth of
liquids, it shall be assumed that the contents are completely
double bottom or 350 mm whichever is less. Where there
lost from that compartment and replaced by salt water up
is no double bottom, the protrusion below the upper limit
to the level of the final plane of equilibrium.
of bottom damage is not to exceed 350 mm. Suction wells
installed in accordance with this paragraph may be ignored
in determining the compartments affected by damage.

Fig. 2.1 Typical cargo tank location

2.7.4 Where the damage between transverse watertight transverse bulkheads shall be spaced at least at a distance
bulkheads is envisaged as specified in 2.8.1.4, .5 and .6, equal to the longitudinal extent of damage specified in
2-4 Section 2 - Ship Survival Capability and Location of Cargo Tanks

2.5.1.1.1 in order to be considered effective. Where

transverse bulkheads are spaced at a lesser distance, one .2 A Type 2G ship of more than 150 m in length
or more of these bulkheads within such extent of damage shall be assumed to sustain damage anywhere in
should be assumed as non-existent for the purpose of its length;
determining flooded compartments. Further, any portion
.3 A Type 2G ship of 150 m in length or less shall
of a transverse bulkhead bounding side compartments or
be assumed to sustain damage anywhere in its
double bottom compartments shall be assumed damaged
length, except involving either of the bulkheads
if the watertight bulkhead boundaries are within the extent
bounding a machinery space located aft;
of vertical or horizontal penetration required by 2.5. Also,
any transverse bulkhead shall be assumed damaged if it .4 A Type 2PG ship shall be assumed to sustain
contains a step or recess of more than 3 m in length located damage anywhere in its length, except involving
within the extent of penetration of assumed damage. The transverse bulkheads spaced further apart than the
step formed by the after peak bulkhead and after peak tank longitudinal extent of damage as specified in
top shall not be regarded as a step for the purpose of this 2.5.1.1.1;
paragraph.
.5 A Type 3G ship of 125 m in length or more shall
2.7.5 The ship shall be so designed as to keep be assumed to sustain damage anywhere in its
asymmetrical flooding to the minimum consistent with length, except involving transverse bulkheads
efficient arrangements. spaced further apart than the longitudinal extent
of damage specified in 2.5.1.1.1;
2.7.6 Equalization arrangements requiring mechanical
.6 A Type 3G ship of less than 125 m in length shall
aids such as valves or cross-levelling pipes, if fitted, shall
be assumed to sustain damage anywhere in its
not be considered for the purpose of reducing an angle of
length, except involving transverse bulkheads
heel or attaining the minimum range of residual stability
spaced further apart than the longitudinal extent
to meet the requirements of 2.9.1 and sufficient residual
of damage specified in 2.5.1.1.1 and except damage
stability shall be maintained during all stages where
involving the machinery space when located aft.
equalization is used. Spaces which are linked by ducts of
However, the ability to survive the flooding of the
large cross-sectional area may be considered to be common.
machinery space shall be considered by the
Administration.
2.7.7 If pipes, ducts, trunks or tunnels are situated within
the assumed extent of damage penetration, as defined in
2.5 arrangements shall be such that progressive flooding 2.8.2 In the case of small Type 2G/2PG and Type 3G
cannot thereby extend to compartments other than those ships which do not comply in all respects with the
assumed to be flooded for each case of damage. appropriate requirements of 2.8.1.3, .4 and .6, special
dispensations may only be considered by the Administration
2.7.8 The buoyancy of any superstructure directly above provided that alternative measures can be taken which
the side damage shall be disregarded. The unflooded parts maintain the same degree of safety. The nature of the
of superstructures beyond the extent of damage, however, alternative measures shall be approved and clearly stated
may be taken into consideration provided that: and be available to the Port Administration. Any such
dispensation shall be duly noted on the International
.1 they are separated from the damaged space by Certificate of Fitness for the Carriage of Liquefied Gases
watertight divisions and the requirements of 2.9.1.1 in Bulk.
in respect of these intact spaces are complied with;
and 2.8-0.1 The longitudinal extent of damage to superstructure
.2 openings in such divisions are capable of being (see also 2.7.8) in the instance of side damage to a machinery
closed by remotely operated sliding watertight space aft under 2.8.1 shall be the same as the longitudinal
doors, and unprotected openings are not immersed extent of the side damage to the machinery space (see
within the minimum range of residual stability Fig. 2.2).
required in 2.9.2.1; however, the immersion of any
other openings capable of being closed weathertight 2.9 Survival requirements
may be permitted.
Ships subject to the Code shall be capable of surviving the
2.8 Standard of damage assumed damage specified in 2.5 to the standard provided
in 2.8 in a condition of stable equilibrium and shall satisfy
2.8.1 Ships shall be capable of surviving the damage the following criteria:
indicated in 2.5 with the flooding assumptions in 2.7 to the
extent determined by the ship's type according to the
following standards:

.1 A Type 1G ship shall be assumed to sustain

damage anywhere in its length;
 Section 2 - Ship Survival Capability and Location of Cargo Tanks 2-5

lever of at least 0,1 m within the 20/ range; the

Fig. 2.2 Longitudinal extent of damage to super- area under the curve within this range shall not
structure be less than 0,0175 meter radians. Unprotected
openings shall not be immersed within this range
unless the space concerned is assumed to be
2.9.1 In any stage of flooding: flooded. Within this range, the immersion of any
of the openings listed in 2.9.1.1 and of other
.1 The waterline taking into account sinkage, heel
openings capable of being closed weathertight may
and trim shall be below the lower edge of any
be permitted; and
opening through which progressive or
downflooding may take place. Such openings shall .2 the emergency source of power shall be capable
include air pipes and openings which are closed of operating.
by means of weathertight doors or hatch covers,
and may exclude those openings closed by means 2.9-0.1 The 20/ range may be measured from any angle
of watertight manhole covers and watertight flush commencing between the position of equilibrium and the
scuttles, small watertight cargo tank hatch covers angle of 30/, see Fig. 2.3.
which maintain the high integrity of the deck,
remotely operated watertight sliding doors, and
side scuttles of the non-opening type.
.2 the maximum angle of heel due to unsymmetrical
flooding shall not exceed 30/; and
.3 the residual stability during intermediate stages
of flooding shall be to the satisfaction of the
Administration. However, it shall never be
significantly less than that required by 2.9.2.1.
h = righting lever
2.9.2 At final equilibrium after flooding:
1 = progressive flooding angle
.1 the righting lever curve shall have a minimum
range of 20/ beyond the position of equilibrium Fig. 2.3 Range of positive stability where the residual
in association with a maximum residual righting stability should be evaluated