1 The hypothetical
outflow of oil in the case of side damage (Oc) and bottom
damage (Os) shall be calculated by the following formulae
with respect to compartments breached by damage to all conceivable
locations along the length of the ship to the extent as defined in regulation 24 of this Annex.
2 If a
void space or segregated ballast tank of a length less than l
c as defined in regulation
24 of this Annex is located between wing oil tanks, Oc in
formula (I) may be calculated on the basis of volume Wi being
the actual volume of one such tank (where they are of equal capacity)
or the smaller of the two tanks (if they differ in capacity) adjacent
to such space, multiplied by Si as defined below and taking
for all other wing tanks involved in such collision the value of the
actual full volume.
|
where l
i
|
= |
length in metres of void space or segregated ballast tank under
consideration. |
-
3.1 Credit shall only be given in respect of double
bottom tanks which are either empty or carrying clean water when cargo
is carried in the tanks above.
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3.2 Where the double bottom does not extend for
the full length and width of the tank involved, the double bottom
is considered non-existent and the volume of the tanks above the area
of the bottom damage shall be included in formula (II) even if the
tank is not considered breached because of the installation of such
a partial double bottom.
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3.3 Suction wells may be neglected in the determination
of the value hi provided such wells are not excessive in
area and extend below the tank for a minimum distance and in no case
more than half the height of the double bottom. If the depth of such
a well exceeds half the height of the double bottom, hi shall
be taken equal to the double bottom height minus the well height.
Piping serving such wells if installed within the double bottom
shall be fitted with valves or other closing arrangements located
at the point of connection to the tank served to prevent oil outflow
in the event of damage to the piping. Such piping shall be installed
as high from the bottom shell as possible. These valves shall be kept
closed at sea at any time when the tank contains oil cargo, except
that they may be opened only for cargo transfer needed for the purpose
of trimming of the ship.
4 In the case where
bottom damage simultaneously involves four centre tanks, the value
of Os may be calculated according to the formula:
|
O
s
|
= |
1/4 (Σ Z
i
W
i + Σ Z
i
C
i)
|
5 An Administration
may credit as reducing oil outflow in case of bottom damage, an installed
cargo transfer system having an emergency high suction in each cargo
oil tank, capable of transferring from a breached tank or tanks to
segregated ballast tanks or to available cargo tankage if it can be
assured that such tanks will have sufficient ullage. Credit for such
a system would be governed by ability to transfer in two hours of
operation oil equal to one half of the largest of the breached tanks
involved and by availability of equivalent receiving capacity in ballast
or cargo tanks. The credit shall be confined to permitting calculation
of Os according to formula (III). The pipes for such suctions
shall be installed at least at a height not less than the vertical
extent of the bottom damage vs. The Administration shall
supply the Organization with the information concerning the arrangements
accepted by it, for circulation to other Parties to the Convention.
6 This
regulation does not apply to oil tankers delivered on or after 1 January
2010, as defined in regulation
1.28.8.