MARPOL Consolidated Edition 2017

Annex I: Regulations for the prevention of pollution by oil
Regulation 18
13 Segregated ba llast tanks and spaces other than oil tanks w ithin the cargo tanks length (L 1
) shall be so
arranged as to comply with the following requirement:
where:
I:PAC + I:PAS 2: / !L1(B + 20)]
PA, = the side shel l area in square metres for each segregated ballast tank or space other than an oil
tank based on projected moulded dimensions,
PA 5
= the bottom shell area in square metres for each such tank or space based on projected moulded
dimensions,
L 1
= length in metres between the forward and after extremities of the cargo tanks,
8 = maximum breadth of the ship in metres as defined in regu lation 1.22 of this Annex,
D
I
= moulded depth in metres measured vertically from the top of the keel to the top of the freeboard
deck beam at side am idships. In ships having rounded gunwales, the moulded depth shall be
measured to the point of intersection of the moulded lines of the deck and side shel l plating, the
lines extending as though the gunwale were of angular design,
= 0.45 for oil tankers of 20,000 tonnes deadweight, 0.30 for oil tankers of 200,000 tonnes
deadweight and above, subject to the provisions of paragraph 14 of this regu lation.
For intermediate va lues of deadweight the value of/ shall be determined by linear interpolation.
Whenever symbols given in this paragraph appear in this regulation, they have the meaning as defined
in this paragraph.
SEE INTERPRETATION 40
14 For tankers of 200,000 tonnes deadweight and above the value of/ may be reduced as follows:
where:
/ (
a
a
a
Oc + Os)
reduced = / - a - 40A or 0.2 w hichever is greater
= 0.25 for oil tankers of 200,000 tonnes deadweight,
= 0.40 for oil tan kers of 300,000 tonnes deadweight,
= 0.50 for oil tankers of 420,000 tonnes deadweight and above.
For intermediate va lues of deadweight the value of a shall be determined by linear interpolation.
O, = as defined in regulation 25.1.1 of this Annex,
Os = as defined in regulation 25.1.2 of this An nex,
OA = the allowable oil outflow as required by regulation 26.2 of this Annex.
SEE INTERPRETATION 40
15 In the determination of PAc and PAs for segregated ballast tanks and spaces other than oil tanks the
following shall apply:
.1 the minimum w idth of each wing tank or space either of w hich extends for the ful l depth of the
ship's side or from the deck to the top of the double bottom shall be not less than 2 m. The width
sha ll be measured inboard from the sh ip's side at right angles to the centreline. Where a lesser
width is provided, the w ing tank or space shall not be taken into account when ca lculating the
protecting area PA,; and
.2 the minimum vertical depth of each double bottom tank or space shall be 1
~ or 2 m, whichever
is the lesser. Where a lesser depth is provided, the bottom tank or space shall not be taken into
account when calculating the protecting area PAs·
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MARPOL CONSOLIDATED EDITI ON 2017