Ingangsdatum: 03-02-2000
Geldig tot en met: 31-12-2004
(1) For the purposes of freeboard computation, ships shall be divided into type 'A' and
type 'B'.
Type 'A' ships
(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 A of
regulation 28.
Type 'B' ships
(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 hatchways fitted with hatch covers which
comply with the requirements of regulation 15, other than paragraph (7), shall be assigned
free boards based upon the values gives in table B of regulation 28, increased by the
values given in the following table:
FREEBOARD INCREASE OVER TABULAR FREEBOARD FOR TYPE 'B'
SHIPS, FOR SHIPS WITH HATCH COVERS NOT COMPLYING WITH
REGULATION 15(7) OR REGULATION 16

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 15 (7) or regulation 16, shall, except as provided in
paragraphs (8) to (13) inclusive of this regulation, be assigned freeboards based on table B
of regulation 28.
(8) Any type 'B' ship of over 100 m in length may be assigned free boards 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 positions 1 and 2 comply with the provisions of regulation 16
and have adequate strength, special care being given to their sealing and
securing arrangements; 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 B of regulation 28 shall not be
reduced by more than 60% of the difference between the B and A tabular values 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 A and those in
table B of regulation 28 on condition that the ship complies with the
requirements of :
(i) regulation 26, other than paragraph (4), as if it were a type 'A' ship;
(ii) paragraphs (8), (11) and (13) of this regulation; and
(iii) paragraph (12) of this regulation, 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.
Initial condition of loading
(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 (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 (ii).
(iv) 50% of the individual total capacity of all tanks and spaces fitted to contain
consumable liquids 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) At an angle of heel of not more than 5 °in each compartment containing
liquids, as prescribed in (ii) except that in the case of compartments
containing consumable fluids, as prescribed in (iv), the maximum free
surface effect shall be taken into account. Alternatively, the actual free
surface effects may be used, provided the methods of calculation are
acceptable to the Administration.
(vi) Weights shall be calculated on the basis of the following values for specific
gravities:
salt water 1.025
fresh water 1.000
oil fuel 0.950
diesel oil 0.900
lubricating oil 0.900
Damage assumptions
(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 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 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 after peak
bulkhead and the after peak 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 3m, 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 L 2/3 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 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 or
regulation 19(4)), 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
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.
Ships without means of propulsion
(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 (2), 26 (3) 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.