S.I. No. 788/2007 - Sea Pollution (Prevention of Oil Pollution) Regulations 2007

• (6) The Oil Record Book Part I shall be kept in such a place as to be readily available for inspection at all reasonable times and, except in the case of unmanned ships under tow, shall be kept on board the ship. It shall be preserved for a period of 3 years after the last entry has been made.

• (7) An inspector may inspect the Oil Record Book Part I on board any ship to which these Regulations apply while the ship is in a port or in an offshore terminal in the State and may make a copy of any entry in that book and may require the master of the ship to certify that the copy is a true copy of such entry. The inspection of an Oil Record Book Part I and the taking of a certified copy by the inspector under this paragraph shall be performed as expeditiously as possible without causing the ship to be unduly delayed.

• (8) The master of a ship to which this Regulation applies shall ensure that paragraphs (2) to (6) are complied with in relation to the ship.

PART 4 Requirements for the cargo area of oil tankers

Chapter 1 Construction

Segregated ballast tanks

• (2) The capacity of the segregated ballast tanks shall be so determined that the ship may operate safely on ballast voyages without recourse to the use of cargo tanks for water ballast except as provided for in paragraph (3) or (4). In all cases, however, the capacity of segregated ballast tanks shall be at least such that, in any ballast condition at any part of the voyage, including the conditions consisting of lightweight plus segregated ballast only, the ship’s draughts and trim can meet each of the following requirements:

• (a) the moulded draught amidships (dm) in metres (without taking into account any ship’s deformation) shall not be less than:

dm = 2.0 + 0.02L;

• (b) the draughts at the forward and after perpendiculars shall correspond to those determined by the draught amidships (dm) as specified in subparagraph (a), in association with the trim by the stern of not greater than 0.015L;

• (c) in any case the draught at the after perpendicular shall not be less than that which is necessary to obtain full immersion of the propeller or propellers, as the case may be.

• (3) Ballast water shall not be carried in cargo tanks, except—

• (a) on those rare voyages when weather conditions are so severe that, in the opinion of the master, it is necessary to carry additional ballast water in cargo tanks for the safety of the ship;

• (b) in exceptional cases where the particular character of the operation of an oil tanker renders it necessary to carry ballast water in excess of the quantity required under paragraph (2), but only if such operation of the oil tanker falls under the category of exceptional cases as established by the Organization.

Such additional ballast water shall be processed and discharged in compliance with Regulation 34 and an entry shall be made in the Oil Record Book Part II referred to in Regulation 36.

• (4) In the case of crude oil tankers, the additional ballast permitted in paragraph (3) shall be carried in cargo tanks only if such tanks have been crude oil washed in accordance with Regulation 35 before departure from an oil unloading port or terminal.

• (5) Notwithstanding the provisions of paragraph (2), the segregated ballast conditions for oil tankers less than 150 metres in length shall be to the satisfaction of the Minister.

• (6) Subject to the provisions of paragraph (7), every crude oil tanker of 40,000 tonnes deadweight and above delivered on or before 1 June 1982, shall be provided with segregated ballast tanks and shall comply with the requirements of paragraphs (2) and (3).

• (7) Crude oil tankers referred to in paragraph (6) may, in lieu of being provided with segregated ballast tanks, operate with a cargo tank cleaning procedure using crude oil washing in accordance with Regulations 33 and 35 unless the crude oil tanker is intended to carry crude oil which is not suitable for crude oil washing.

• (8) Every product carrier of 40,000 tonnes deadweight and above delivered on or before 1 June 1982, shall be provided with segregated ballast tanks and shall comply with the requirements of paragraphs (2) and (3), or, alternatively, operate with dedicated clean ballast tanks in accordance with the following provisions:

• (a) the product carrier has adequate tank capacity, dedicated solely to the carriage of clean ballast to meet the requirements of paragraphs (2) and (3);

• (b) the arrangements and operational procedures for dedicated clean ballast tanks shall comply with the requirements established by the Minister, and such requirements shall contain at least all the provisions of the revised Specification for Oil Tankers with Dedicated Clean Ballast Tanks adopted by the Organization by resolution A.495(XII);

• (c) the product carrier shall be equipped with an oil content meter, approved by the Minister on the basis of specifications recommended by the Organization, to enable supervision of the oil content in ballast water being discharged;

• (d) every product carrier operating with dedicated clean ballast tanks shall be provided, to the satisfaction of the Minister, with a Dedicated Clean Ballast Tank Operation Manual detailing the system and specifying operational procedures, as set out in IMO Resolution A.495(XII), and shall contain all the information set out in the Specifications referred to in subparagraph (b); if an alteration affecting the dedicated clean ballast tanks system is made, the Operation Manual shall be revised accordingly and the revision submitted to the Minister for approval.

• (9) Any oil tanker which is not required to be provided with segregated ballast tanks in accordance with paragraph (1), (6) or (8) may, however, be qualified as a segregated ballast tanker, provided that it complies with the requirements of paragraphs (2) and (3), or paragraph (5), as appropriate.

• (10)
• (a) Where an oil tanker delivered on or before 1 June 1982, is so constructed or operates in such a manner that it complies at all times with the draught and trim requirements set out in paragraph (2) without recourse to the use of ballast water, it shall be deemed to comply with the segregated ballast tank requirements referred to in paragraph (6) but only if the following conditions are complied with:

• (i) operational procedures and ballast arrangements have been approved by the Minister;

• (ii) agreement is reached between the State and the Governments of the port Parties concerned when the draught and trim requirements are achieved through an operational procedure;

• (iii) the IOPP Certificate is endorsed to the effect that the oil tanker is operating with special ballast arrangements.

• (b) The master of an oil tanker to which subparagraph (a) relates shall ensure that ballast water is not carried in oil tanks except on those rare voyages when weather conditions are so severe that, in the opinion of the master, it is necessary to carry additional ballast water in cargo tanks for the safety of the ship. Such additional ballast water shall be processed and discharged in compliance with Regulation 34 and in accordance with the requirements of Regulations 29, 31 and 32 and entry shall be made in the Oil Record Book Part II referred to in Regulation 36.

• (11) Oil tankers of 70,000 tonnes deadweight and above delivered after 31 December 1979, shall be provided with segregated ballast tanks and shall comply with paragraphs (2), (3) and (4), or paragraph (5), as appropriate.

• (12) Every crude oil tanker of 20,000 tonnes deadweight and above and every product carrier of 30,000 tonnes deadweight and above delivered after 1 June 1982, except those tankers that meet the requirements of Regulation 20, the segregated ballast tanks required to provide the capacity to comply with the requirements of paragraph (2), which are located within the cargo tank length, shall be arranged in accordance with the requirements of paragraphs (13), (14) and (15) to provide a measure of protection against oil outflow in the event of grounding or collision.

• (13) Segregated ballast tanks and spaces other than oil tanks within the cargo tank length (L t ) shall be so arranged as to comply with the following requirement:

ΣPAC + PAS ≥ J [Lt(B + 2D)]

where :

PAC = the side shell area in square metres for each segregated ballast tank or space other than an oil tank based on projected moulded dimensions,

PAS= the bottom shell area in square metres for each such tank or space based on projected moulded dimensions,

Lt = length in metres between the forward and after extremities of the cargo tanks,

B = maximum breadth of the ship in metres as defined in Regulation 2(1),

D = moulded depth in metres measured vertically from the top of the keel to the top of the freeboard deck beam at side amidships. 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 shell plating, the lines extending as though the gunwale were of angular design,

J = 0.45 for oil tankers of 20,000 tonnes deadweight, 0.30 for oil tankers of 200,000 tonnes deadweight and above, subject to paragraph (14).

For intermediate values of deadweight the value of “J” shall be determined by linear interpolation.

For the purposes of this Regulation, the symbols in this paragraph shall have the meaning assigned to them in this paragraph.

• (14) For tankers of 200,000 tonnes deadweight and above the value of “J” may be reduced as follows:

J reduced = [image omitted] or 0.2 whichever is greater

where:

a = 0.25 for oil tankers of 200,000 tonnes deadweight,

a = 0.40 for oil tankers of 300,000 tonnes deadweight,

a = 0.50 for oil tankers of 420,000 tonnes deadweight and above.

For intermediate values of deadweight the value of “a” shall be determined by linear interpolation.

OC = as defined in Regulation 25(1)(a),

OS = as defined in Regulation 25(1)(b),

OA = the allowable oil outflow as required by Regulation 26 (b).

• (15) In the determination of “ PAC” and “ PAS ” for segregated ballast tanks and spaces other than oil tanks the following shall apply:

• (a) the minimum width of each wing tank or space either of which extends for the full depth of the ship’s side or from the deck to the top of the double bottom shall be not less than 2 metres; the width shall be measured inboard from the ship’s side at right angles to the centre line; where a lesser width is provided the wing tank or space shall not be taken into account when calculating the protecting area “PAC”; and

• (b) the minimum vertical depth of each double bottom tank or space shall be B/15 or 2 metres, 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 ”.

The minimum width and depth of wing tanks and double bottom tanks shall be measured clear of the bilge area and, in the case of minimum width, shall be measured clear of any rounded gunwale area.

Double hull and double bottom requirements for oil tankers delivered on or after 6 July 1996

• (2) Every oil tanker of 5,000 tonnes deadweight and above shall—

• (a) in lieu of paragraphs (12) to (15) of Regulation 19, as applicable, comply with the requirements of paragraph (3) unless it is subject to the provisions of paragraphs (4) and (5),

• (b) comply, if applicable, with the requirements of Regulation 28(6).

• (3) The entire cargo tank length shall be protected by ballast tanks or spaces other than cargo and fuel oil tanks as follows:

• (a) wing tanks or spaces:

wing tanks or spaces shall extend either for the full depth of the ship’s side or from the top of the double bottom to the uppermost deck, disregarding a rounded gunwale where fitted. They shall be arranged such that the cargo tanks are located inboard of the moulded line of the side shell plating, nowhere less than the distance w which, as shown in Figure 2, which is set out in Schedule 4, is measured at any cross-section at right angles to the side shell, as specified below:

w = 2.0m, whichever is the lesser;

with a minimum value of w = 1.0m;

• (b) double bottom tanks or spaces:

at any cross-section the depth of each double bottom tank or space shall be such that the distance h between the bottom of the cargo tanks and the moulded line of the bottom shell plating measured at right angles to the bottom shell plating as shown in Figure 2, which is set out in Schedule 4, is not less than specified below:

h = B/15(m) or,

h = 2.0m, whichever is the lesser;

with a minimum value of h = 1.0m;

• (c) turn of the bilge area or at locations without a clearly defined turn of the bilge:

when the distances h and w are different, the distance w shall have preference at levels exceeding 1.5h above the baseline as shown in Figure 2, which is set out in Schedule 4;

• (d) the aggregate capacity of ballast tanks:

on crude oil tankers of 20,000 tonnes deadweight and above and product carriers of 30,000 tonnes deadweight and above, the aggregate capacity of wing tanks, double bottom tanks, forepeak tanks and after peak tanks shall not be less than the capacity of segregated ballast tanks necessary to meet the requirements of Regulation 19; wing tanks or spaces and double bottom tanks used to meet the requirements of that Regulation shall be located as uniformly as practicable along the cargo tank length; additional segregated ballast capacity provided for reducing longitudinal hull girder bending stress, trim, etc., may be located anywhere within the ship;

• (e) suction wells in cargo tanks:

suction wells in cargo tanks may protrude into the double bottom below the boundary line defined by the distance h, but only if such wells are as small as practicable and the distance between the well bottom and bottom shell plating is not less than 0.5h;

• (f) ballast and cargo piping:

ballast piping and other piping such as sounding and vent piping to ballast tanks shall not pass through cargo tanks; cargo piping and similar piping to cargo tanks shall not pass through ballast tanks; exemptions to this requirement may be granted for short lengths of piping, provided that they are completely welded or equivalent.

• (4) The following applies for double bottom tanks or spaces:

• (a) double bottom tanks or spaces as required by paragraph (3)(b) may be dispensed with, provided that the design of the tanker is such that the cargo and vapour pressure exerted on the bottom shell plating forming a single boundary between the cargo and the sea does not exceed the external hydrostatic water pressure, as expressed by the following formula:

f x hC x pC x g + p ≤ dn x ps x g

where:

hC = height of cargo in contact with the bottom shell plating in metres,

pC = maximum cargo density in kg/m³,

dn = minimum operating draught under any expected loading condition in meters,

pS = density of seawater in kg/m³,

p = maximum set pressure above atmospheric pressure (gauge pressure) of pressure/vacuum valve provided for the cargo tank in Pa provided for the cargo tank in bars,

f = safety factor = 1.1,

g = standard acceleration of gravity (9.81 m/s²);

• (b) any horizontal partition necessary to fulfil the requirements of subparagraph (a) shall be located at a height of not less than B/6 or 6 m, whichever is the lesser, but not more than 0.6D, above the baseline where D is the moulded depth amidships;

• (c) the location of wing tanks or spaces shall be as defined in paragraph (3)(a), except that, below a level 1.5 h above the baseline where h is as defined in paragraph (3)(b), the cargo tank boundary line may be vertical down to the bottom plating, as shown in Figure 4, which is set out in Schedule 4.

• (5) Other methods of design and construction of oil tankers may also be accepted as alternatives to the requirements prescribed in paragraph (3), provided that such methods ensure at least the same level of protection against oil pollution in the event of collision or stranding and are approved in principle by the Organization.

• (6) Every oil tanker of less than 5,000 tonnes deadweight shall comply with paragraphs (3) and (4), or shall—

• (a) at least be fitted with double bottom tanks or spaces having such a depth that the distance h specified in paragraph (3)(b) complies with the following:

h = B/15 (m),

with a minimum value of h = 0.76m;

in the turn of the bilge area and at locations without a clearly defined turn of the bilge, the cargo tank boundary line shall run parallel to the line of the midship flat bottom as shown in Figure 1, which is set out in Schedule 4, and

• (b) be provided with cargo tanks so arranged that the capacity of each cargo tank does not exceed 700 m³ unless wing tanks or spaces are arranged in accordance with paragraph (3)(a) complying with the following:

with a minimum value of w = 0.76 m.

• (7) Oil shall not be carried in any space extending forward of a collision bulkhead located in accordance with Regulation II —1/11 of the International Convention for the Safety of Life at Sea, 1974, as amended. An oil tanker that is not required to have a collision bulkhead in accordance with that Regulation shall not carry oil in any space extending forward of the transverse plane perpendicular to the centreline that is located as if it were a collision bulkhead located in accordance with that Regulation.

• (8) In approving the design and construction of oil tankers to be built in accordance with the provisions of this Regulation, a qualified person shall have due regard to the general safety aspects including the need for the maintenance and inspections of wing and double bottom tanks or spaces.

Double hull and double bottom requirements for oil tankers delivered before 6 July 1996

Pump-room bottom protection

• (2) The pump-room shall be provided with a double bottom such that at any cross-section the depth of each double bottom tank or space shall be such that the distance h between the bottom of the pump-room and the ship’s base line measured at right angles to the ship’s base line is not less than specified below:

h = B/15(m) or

h = 2 m,

whichever is the lesser, and where the minimum value of h = 1 m.

• (3) In case of pump rooms whose bottom plate is located above the base line by at least the minimum height required in paragraph (2)(such as gondola stern designs), a double bottom construction in way of the pump-room is not necessary.

• (4) Ballast pumps shall be provided with suitable arrangements to ensure efficient suction from double bottom tanks.

• (5) Notwithstanding the provisions of paragraphs (2) and (3), where the flooding of the pump-room would not render the ballast or cargo pumping system inoperative, a double bottom need not be fitted.

Accidental oil outflow performance

• (2) In this Regulation—

“breadth (BB)” means the greatest moulded breadth of the ship, in metres, at or below the waterline dB;

“breadth (BS)” means the greatest moulded breadth of the ship, in metres, at or below the deepest load line dS;

“depth (DS)” means the moulded depth, in metres, measured at mid-length to the upper deck at side;

“load line draught (dS)” means the vertical distance, in metres, from the moulded baseline at mid-length to the waterline corresponding to the summer freeboard to be assigned to the ship; calculations pertaining to this Regulation to be based on draught dS, notwithstanding assigned draughts that may exceed dS, such as the tropical loadline;

“waterline (dB)” means the vertical distance, in metres, from the moulded baseline at mid-length to the waterline corresponding to 30 per cent of the depth DS.

• (3) To provide adequate protection against oil pollution in the event of collision or stranding the following shall be complied with:

• (a) for oil tankers of 5,000 tonnes deadweight (DWT) and above, the mean oil outflow parameter shall be as follows:

OM ≤ 0.015	for C ≤ 200,000m3
OM ≤ 0.012 + (0.003/200,000)(400,000-C)	for 200,000m3 < C < 400,000m3
OM ≤ 0.012	for C = 400,000m3

for combination carriers between 5,000 tonnes deadweight (DWT) and 200,000m³ capacity, the mean oil outflow parameter may be applied, provided calculations are submitted to the satisfaction of a qualified person, demonstrating that after accounting for its increased structural strength, the combination carrier has at least equivalent oil outflow performance to a standard double hull tanker of the same size having a OM ≤ = 0.015

OM ≤ 0.021	for C ≤100,000m3
OM ≤ 0.015 + (0.006/100,000)(200,000-C)	for 100,000m3 < C ≤200,000m3

where:

OM = mean oil outflow parameter

C = total volume of cargo oil, in m³, at 98 per cent tank filling

• (b) for oil tankers of less than 5,000 tonnes deadweight (DWT):

the length of each cargo tank shall not exceed 10 m or one of the following values, whichever is the greater:

• (i) where no longitudinal bulkhead is provided inside the cargo tanks:

[image omitted] but not to exceed 0.2L

• (ii) where a centreline longitudinal bulkhead is provided inside the cargo tanks:

• (iii) where 2 or more longitudinal bulkheads are provided inside the cargo tanks:

• (I) for wing cargo tanks: 0.2L

• (II) for centre cargo tanks:

• (A) if [image omitted]

• (B) if [image omitted]

— where no centreline longitudinal bulkhead is provided:

— where a centreline longitudinal bulkhead is provided:

where bi is the minimum distance from the ship’s side to the outer longitudinal bulkhead of the tank in question measured inboard at right angles to the centreline at the level corresponding to the assigned summer freeboard.

• (4) The following general assumptions shall apply when calculating the mean oil outflow parameter:

• (a) the cargo block length extends between the forward and aft extremities of all tanks arranged for the carriage of cargo oil, including slop tanks;

• (b) where this Regulation refers to cargo tanks, it shall be understood to include all cargo tanks, slop tanks and fuel tanks located within the cargo block length;

• (c) the ship shall be assumed loaded to the load line draught dS without trim or heel;

• (d) all cargo oil tanks shall be assumed loaded to 98 per cent of their volumetric capacity and the nominal density of the cargo oil (ρn) shall be calculated as follows:

ρn = 1000 (DWT)/C (kg/m³);

• (e) for the purposes of these outflow calculations, the permeability of each space within the cargo block, including cargo tanks, ballast tanks and other non-oil spaces shall be taken as 0.99, unless proven otherwise;

• (f) suction wells may be neglected in the determination of tank location provided that such wells are as small as practicable and the distance between the well bottom and bottom shell plating is not less than 0.5h, where h is the height as defined in Regulation 20(3)(b).

• (5) The following assumptions shall be used when combining the oil outflow parameters:

• (a) the mean oil outflow shall be calculated independently for side damage and for bottom damage and then combined into the non-dimensional oil outflow parameter OM, as follows:

OM = (0.4 OMS + 0.6 OMB) / C

where:

OMS = mean outflow for side damage, in m³;

OMB = mean outflow for bottom damage, in m³;

• (b) for bottom damage, independent calculations for mean outflow shall be done for 0 m and minus 2.5 m tide conditions, and then combined as follows:

OMB = 0.7 OMB(0) + 0.3 OMB(2.5)

where:

OMB(0) = mean outflow for 0 m tide condition;

OMB(2.5) = mean outflow for minus 2.5 m tide condition, in m³.

• (6) The mean outflow for side damage OMS shall be calculated as follows:

where:

i = represents each cargo tank under consideration;

n = total number of cargo tanks;

PS(i) = the probability of penetrating cargo tank i from side damage, calculated in accordance with paragraph (8)(a);

OS(i) = the outflow, in m³, from side damage to cargo tank i, which is assumed equal to the total volume in cargo tank i at 98 per cent filling, unless it is proven through the application of the Guidelines referred to in Regulation 20(5) that any significant cargo volume will be retained;

C3 = 0.77 for ships having two longitudinal bulkheads inside the cargo tanks, provided these bulkheads are continuous over the cargo block and PS(i) is developed in accordance with this Regulation. C3 equals 1.0 for all other ships or when PS(i) is developed in accordance with paragraph (10).

• (7) The mean outflow for bottom damage shall be calculated for each tidal condition as follows:

• (a) [image omitted]

where:

i = represents each cargo tank under consideration;

n = the total number of cargo tanks;

PB(i) = the probability of penetrating cargo tank i from bottom damage, calculated in accordance with, paragraph (9)(a);

OB(i) = the outflow from cargo tank i, in m³, calculated in accordance with paragraph (7)(c) of this Regulation;

CDB(i) = factor to account for oil capture as defined in paragraph (7)(d);

• (b) [image omitted]

where:

i, n, PB(i) and CDB(i) = as defined in subparagraph (a);

OB(i) = the outflow from cargo tank i, in m³, after tidal change;

• (c) the oil outflow OB(i) for each cargo oil tank shall be calculated based on pressure balance principles, in accordance with the following assumptions:

• (i) the ship shall be assumed stranded with zero trim and heel, with the stranded draught prior to tidal change equal to the load line draught dS;

• (ii) the cargo level after damage shall be calculated as follows:

hc = { (dS + tc — Zl)(ρS) — (1000 p) / g } / ρn

where:

hc = the height of the cargo oil above Zl, in metres;

tc = the tidal change, in m. Reductions in tide shall be expressed as negative values;

Zl = the height of the lowest point in the cargo tank above baseline, in m;

ρS = density of seawater, to be taken as 1,025 kg/m³;

p = if an inert gas system is fitted, the normal overpressure, in kPa, to be taken as not less than 5 kPa; if an inert gas system is not fitted, the overpressure may be taken as 0;

g = the acceleration of gravity, to be taken as 9.81 m/s²;

ρn = nominal density of cargo oil, calculated in accordance with paragraph (4)(d);

• (iii) for cargo tanks bounded by the bottom shell, unless proven otherwise, oil outflow OB(i) shall be taken not less than 1 per cent of the total volume of cargo oil loaded in cargo tank i, to account for initial exchange losses and dynamic effects due to current and waves;

• (d) in the case of bottom damage, a portion from the outflow from a cargo tank may be captured by non-oil compartments; this effect is approximated by application of the factor CDB(i) for each tank, which shall be taken as follows:

CDB(i) = 0.6 for cargo tanks bounded from below by non-oil compartments;

CDB(i) = 1.0 for cargo tanks bounded by the bottom shell.

• (8) The probability PS of breaching a compartment from side damage shall be calculated as follows:

• (a) PS = PSL PSV PST

where:

PSL = 1 - PSf - PSa = probability the damage will extend into the longitudinal zone bounded by Xa and Xf;

PSV = 1 - PSu - PSl = probability the damage will extend into the vertical zone bounded by Zl and Zu;

PST = 1 - PSy = probability the damage will extend transversely beyond the boundary defined by y;

• (b) PSa, PSf, PSl, PSu and PSy shall be determined by linear interpolation from the table of probabilities for side damage provided in paragraph (8)(c), where:

PSa = the probability the damage will lie entirely aft of location Xa /L;

PSf = the probability the damage will lie entirely forward of location Xf /L;

PSl = the probability the damage will lie entirely below the tank;

PSu = the probability the damage will lie entirely above the tank;

PSy = the probability the damage will lie entirely outboard of the tank;

compartment boundaries Xa, Xf, Zl, Zu and y shall be developed as follows:

Xa = the longitudinal distance from the aft terminal of L to the aftmost point on the compartment being considered, in metres;

Xf = the longitudinal distance from the aft terminal of L to the foremost point on the compartment being considered, in metres;

Zl = the vertical distance from the moulded baseline to the lowest point on the compartment being considered, in metres;

Zu = the vertical distance from the moulded baseline to the highest point on the compartment being considered, in metres; Zu is not to be taken greater than DS;

y = the minimum horizontal distance measured at right angles to the centreline between the compartment under consideration and the side shell in metres;

• (c) Table of probabilities for side damage

PSy shall be calculated as follows:

PSy = (24.96 -199.6 y/ BS)(y/BS)	for y/BS ≤ 0.05
PSy = 0.749 + {5 - 44.4 (y/BS - 0.05)} (y/BS - 0.05)	for 0.05 < y/B S < 0.1
PSy = 0.888 + 0.56 (y/BS - 0.1)	for y/BS ≥ 0.1
PSy shall not be taken greater than 1.

• (9) The probability P B of breaching a compartment from bottom damage shall be calculated as follows:

• (a) PB = PBL PBT PBV

where:

PBL = 1 - PBf - PBa = probability the damage will extend into the longitudinal zone bounded by Xa and Xf;

PBT = 1 - PBp - PBs = probability the damage will extend into the transverse zone bounded by Yp and Ys;

PBV = 1 - PBz = probability the damage will extend vertically above the boundary defined by z;

• (b) PBa, PBf, PBp, PBs and PBfz shall be determined by linear interpolation from the table of probabilities for bottom damage provided in paragraph (9)(c), where:

PBa = the probability the damage will lie entirely aft of location Xa /L;

PBf = the probability the damage will lie entirely forward of location Xf /L;

PBp = the probability the damage will lie entirely to port of the tank;

PBs = the probability the damage will lie entirely to starboard of the tank;

PBz = the probability the damage will lie entirely below the tank;

compartment boundaries Xa, Xf, Yp, Ys, and z shall be developed as follows:

Xa and Xf are as defined in paragraph (8)(b);

Yp = the transverse distance from the port-most point on the compartment located at or below the waterline dB, to a vertical plane located BB/2 to starboard of the ship’s centreline, in metres;

Ys = the transverse distance from the starboard-most point on the compartment located at or below the waterline dB, to a vertical plane located BB/2 to starboard of the ship’s centreline, in metres;

z = the minimum value of z over the length of the compartment, where, at any given longitudinal location, z is the vertical distance from the lower point of the bottom shell at that longitudinal location to the lower point of the compartment at that longitudinal location, in metres;

• (c) Table of probabilities for bottom damage

PBz shall be calculated as follows:

PBz = (14.5 - 67 z/DS)(z/DS) for z/DS ≤ 0.1,

PBz = 0.78 + 1.1 (z/DS - 0.1) for z/DS > 0.1;

PBz shall not be taken greater than 1.

• (10) This Regulation uses a simplified probabilistic approach where a summation is carried out over the contributions to the mean outflow from each cargo tank. For certain designs such as those characterized by the occurrence of steps/recesses in bulkheads/decks and for sloping bulkheads and/or a pronounced hull curvature, more rigorous calculations may be appropriate. In such cases one of the following calculation procedures may be applied:

• (a) the probabilities referred to in paragraphs (8) and (9) may be calculated with more precision through application of hypothetical sub-compartments;

• (b) the probabilities referred to in paragraphs (8) and (9) may be calculated through direct application of the probability density functions contained in the Guidelines referred to in Regulation 20 (5);

• (c) the oil outflow performance may be evaluated in accordance with the method described in the Guidelines referred to in Regulation 20(5).

• (11) The following provisions regarding piping arrangements shall apply:

• (a) lines of piping that run through cargo tanks in a position less than 0.30BS from the ship’s side or less than 0.30DS from the ship’s bottom shall be fitted with valves or similar closing devices at the point at which they open into any cargo tank; these valves shall be kept closed at sea at any time when the tanks contain cargo oil, except that they may be opened only for cargo transfer needed for essential cargo operations;

• (b) credit for reducing oil outflow through the use of an emergency rapid cargo transfer system or other system arranged to mitigate oil outflow in the event of an accident may be taken into account only after the effectiveness and safety aspects of the system are approved by the Organization; submittal for approval shall be made in accordance with the provisions of the Guidelines referred to in Regulation 20(5).

Damage assumptions

• (a) side damage

	(i) longitudinal extent (lc):	[image omitted] or 14.5 metres, whichever is less
	(ii) transverse extent (tc)(inboard from the ship’s side at right angles to the centreline at the level corresponding to the assigned summer freeboard):	[image omitted] or 11.5 metres, whichever is less
	(iii) vertical extent (Vc):	from the base line upwards without limit,

• (b) bottom damage

		For 0.3L from the forward perpendicular of the ship	Any other part of the ship
	(i) longitudinal extent (ls):		[image omitted] or 5 metres, whichever is less
	(ii) transverse extent (ts):	[image omitted] or 10 meters, whichever is less, but not less than 5 metres	5 metres
	(iii) vertical extent from the base line (Vs):	[image omitted] or 6 metres, whichever is less.

• (2) Wherever the symbols given in this Regulation appear in this Part, they have the meaning as defined in this Regulation.

Hypothetical outflow of oil

• (a) for side damages:

Oc = ΣWi + Ki Ci

• (b) for bottom damages:

Os = 1/3 (ΣZiWi + ZiCi)

where: Wi = volume of a wing tank in cubic metres assumed to be breached by the damage as specified in Regulation 24; Wi for a segregated ballast tank may be taken equal to zero,

Ci = volume of a centre tank in cubic metres assumed to be breached by the damage as specified in Regulation 24; Ci for a segregated ballast tank may be taken equal to zero,

Ki = 1 - bi / tc when bi is equal to or greater than tc, Ki shall be taken equal to zero,

Zi = 1 - hi / vs when hi is equal to or greater than vs, Zi shall be taken equal to zero,

bi = width of wing tank in metres under consideration measured inboard from the ship’s side at right angles to the centreline at the level corresponding to the assigned summer freeboard,

hi = minimum depth of the double bottom in metres under consideration; where no double bottom is fitted h i shall be taken equal to zero.

Wherever symbols given in this paragraph appear in this Part, they have the meaning as defined in this Regulation.

• (2) If a void space or segregated ballast tank of a length less than l c as defined in Regulation 24 is located between wing oil tanks, Oc in formula (I) in paragraph (1)(a) may be calculated on the basis of volume W i being the actual volume of one such tank (where they are of equal capacity) or the smaller of the 2 tanks (if they differ in capacity) adjacent to such space, multiplied by Si as defined in this paragraph and taking for all other wing tanks involved in such a collision the value of the actual full volume:

Si = 1 — li / lc

where li = length in metres of void space or segregated ballast tank under consideration.

• (3)
• (a) 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.

• (b) 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 for the purposes of the formula in paragraph (1)(b) even if the tank is not considered breached because of the installation of such a partial double bottom.

• (c) 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:

Os = 1/4 (Σi Wi + ΣZi Ci)

• (5) A qualified person 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 O s according to the formula set out in paragraph (4). The pipes for such suctions shall be installed at least at a height not less than the vertical extent of the bottom damage vs.

• (6) This Regulation does not apply to oil tankers delivered on or after 1 January 2010.

Limitation of size and arrangement of cargo tanks

• (a) every oil tanker of 150 gross tonnage and above delivered after 31 December 1979, and

• (b) every oil tanker of 150 gross tonnage and above delivered on or before 31 December 1979, which falls into either of the following categories:

• (i) a tanker, the delivery of which is after 1 January 1977, or

• (ii) a tanker to which both the following conditions apply:

• (I) delivery is not later than 1 January 1977; and

• (II) the building contract is placed after 1 January 1974, or in cases where no building contract has previously been placed, the keel is laid or the tanker is at a similar stage of construction after 30 June 1974.

• (2) Cargo tanks of oil tankers are of such size and arrangements that the hypothetical outflow Oc or Os calculated in accordance with Regulation 25 anywhere in the length of the ship does not exceed 30,000 cubic metres or 400 [image omitted]DW, whichever is the greater, but subject to a maximum of 40,000 cubic metres.

• (3) The volume of any one wing cargo oil tank of an oil tanker does not exceed 75 per cent of the limits of the hypothetical oil outflow referred to in paragraph (2). The volume of any one centre cargo oil tank does not exceed 50,000 cubic metres. However, in segregated ballast oil tankers as defined in Regulation 19, the permitted volume of a wing cargo oil tank situated between two segregated ballast tanks, each exceeding lc in length, may be increased to the maximum limit of hypothetical oil outflow provided that the width of the wing tanks exceeds tc.

• (4) The length of each cargo tank does not exceed 10 metres or one of the following values, whichever is the greater:

• (a) where no longitudinal bulkhead is provided inside the cargo tanks:

[image omitted] but not to exceed 0.2L

but not to exceed 0.2L

• (b) where a centreline longitudinal bulkhead is provided inside the cargo tanks:

• (c) where 2 or more longitudinal bulkheads are provided inside the cargo tanks:

• (i) for wing cargo tanks: 0.2L

• (ii) for centre cargo tanks:

• (I) if [image omitted] is equal to or greater than one-fifth: 0.2L

• (II) if [image omitted] is less than one-fifth:

—where no centreline longitudinal bulkhead is provided:

—where a centreline longitudinal bulkhead is provided:

where bi is the minimum distance from the ship’s side to the outer longitudinal bulkhead of the tank in question measured inboard at right angles to the centreline at the level corresponding to the assigned summer freeboard.

• (5) In order not to exceed the volume limits established by paragraphs (2), (3) and (4) and irrespective of the accepted type of cargo transfer system installed, when such system interconnects 2 or more cargo tanks, valves or other similar closing devices are provided for separating the tanks from each other and that those valves or devices are kept closed when the tanker is at sea.

• (6) Lines of piping which run through cargo tanks in a position less than tc from the ship’s side or less than v c from the ship’s bottom are fitted with valves or similar closing devices at the point at which they open into any cargo tank and that those valves are kept closed at sea at any time when the tanks contain cargo oil, except that they may be opened only for cargo transfer needed for the purpose of trimming of the ship.

• (7) This Regulation does not apply to oil tankers delivered on or after 1 January 2010.

Intact stability

• (a) In port, the initial metacentric height GM°, corrected for free surface measured at 0° heel, shall be not less than 0.15m;

• (b) At sea:

• (i) the area under the righting lever curve (GZ curve) shall be not less than 0.055 m.rad up to θ = 30° angle of heel and not less than 0.09 m.rad up to θ = 40° or other angle of flooding f if this angle is less than 40°; additionally, the area under the righting lever curve (GZ curve) between the angles of heel of 30° and 40° or between 30° and θf, if this angle is less than 40°, shall be not less than 0.03 m.rad;

• (ii) the righting lever GZ shall be at least 0.20m at an angle of heel equal to or greater than 30°;

• (iii) the maximum righting arm shall occur at an angle of heel preferably exceeding 30° but not less than 25°; and

• (iv) the initial metacentric height GM0, corrected for free surface measured at 0° heel, shall be not less than 0.15m.

In this subparagraph, ‘θf’ is the angle of heel at which the openings in the hull, superstructures or deck-houses, which cannot be closed weather tight, immerse. In applying this criterion, small openings through which progressive flooding cannot take place need not be considered as open.

• (2) The requirements of paragraph (1) shall be met through design measures. For combination carriers simple supplementary operational procedures may be allowed.

• (3) Simple supplementary operational procedures for liquid transfer operations referred to in paragraph (2) shall mean written procedures made available to the master which—

• (a) are approved by a qualified person,

• (b) indicate those cargo and ballast tanks which may, under any specific condition of liquid transfer and possible range of cargo densities, be slack and still allow the stability criteria to be met; the slack tanks may vary during the liquid transfer operations and be of any combination provided they satisfy the criteria,

• (c) will be readily understandable to the officer-in-charge of liquid transfer operations,

• (d) provide for planned sequences of cargo/ ballast transfer operations,

• (e) allow comparisons of attained and required stability using stability performance criteria in graphical or tabular form,

• (f) require no extensive mathematical calculations by the officer-in-charge,

• (g) provide for corrective actions to be taken by the officer-in-charge in case of departure from recommended values and in case of emergency situations, and

• (h) are prominently displayed in the approved trim and stability booklet and at the station that controls cargo transfer or ballast transfer or both cargo and ballast transfer operations and in any computer software by which stability calculations are performed.

Subdivision and damage stability

• (a) in tankers of more than 225 metres in length, anywhere in the ship’s length;

• (b) in tankers of more than 150 metres, but not exceeding 225 metres in length, anywhere in the ship’s length except involving either after or forward bulkhead bounding the machinery space located aft; the machinery space shall be treated as a single floodable compartment; and

• (c) in tankers not exceeding 150 metres in length, anywhere in the ship’s length between adjacent transverse bulkheads with the exception of the machinery space, but in tankers of 100 metres or less in length where all requirements of paragraph (3) cannot be fulfilled without materially impairing the operational qualities of the ship, the Minister may exempt the ship from compliance with the requirements concerned.

Ballast conditions where the tanker is not carrying oil in cargo tanks excluding any oil residues, shall not be considered.

• (2) The following provisions regarding the extent and the character of the assumed damage shall apply:

• (a) side damage

	(i) longitudinal extent:	[image omitted] or 14.5 metres, whichever is less
	(ii) transverse extent (inboard from the ship’s side at right angles to the centreline at the level of the summer load line):	[image omitted] or 11.5 metres, whichever is less
	(iii) vertical extent:	From the moulded line of the bottom shell plating at centreline, upwards without limit;

• (b) bottom damage

		For 0.3L from forward perpendicular of the ship	Any other part of the ship
	(i) longitudinal extent:	[image omitted] or 14.5 metres, whichever is less	[image omitted] or 5 metres, whichever is less
	(ii) transverse extent:	[image omitted] or 10 metres, whichever is less	[image omitted] or 5 metres, whichever is less
	(iii) vertical extent:	[image omitted] or 6 metres, whichever is less, measured from the moulded line of the bottom shell plating at centreline;	[image omitted] or 6 metres, whichever is less, measured from the moulded line of the bottom shell plating at centreline;

• (c) if any damage of a lesser extent than the maximum extent of damage specified in subparagraphs (a) and (b) would result in a more severe condition, such damage shall be considered;

• (d) where the damage involving transverse bulkheads is envisaged as specified in paragraphs (1)(a) and (b), transverse watertight bulkheads shall be spaced at least at a distance equal to the longitudinal extent of assumed damage specified in paragraph (2)(a) in order to be considered effective; where transverse bulkheads are spaced at a lesser distance, one or more of these bulkheads within such extent of damage shall be assumed as non-existent for the purpose of determining flooded compartments;

• (e) where the damage between adjacent transverse watertight bulkheads is envisaged as specified in paragraph (1)(c), no main transverse bulkhead or a transverse bulkhead bounding side tanks or double bottom tanks shall be assumed damaged, unless—

• (i) the spacing of the adjacent bulkheads is less than the longitudinal extent of assumed damage specified in paragraph (2)(a), or

• (ii) there is a step or a recess in a transverse bulkhead of more than 3.05 metres in length, located within the extent of penetration of assumed damage; the step formed by the after peak bulkhead and after peak tank top shall not be regarded as a step for the purpose of this Regulation;

• (f) if pipes, ducts or tunnels are situated within the assumed extent of damage, arrangements shall be made so that progressive flooding cannot thereby extend to compartments other than those assumed to be floodable for each case of damage.

• (3) Oil tankers shall be regarded as complying with the damage stability criteria if all of the following requirements are met:

• (a) the final waterline, taking into account sinkage, heel and trim, shall be below the lower edge of any opening through which progressive flooding may take place; such openings shall include air-pipes and those 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 cargo tank hatch covers which maintain the high integrity of the deck, remotely operated watertight sliding doors, and side scuttles of the non-opening type;

• (b) in the final stage of flooding, the angle of heel due to unsymmetrical flooding shall not exceed 25 degrees, provided that this angle may be increased up to 30 degrees if no deck edge immersion occurs;

• (c) the stability in the final stage of flooding shall be investigated and may be regarded as sufficient if the righting lever curve has at least a range of 20 degrees beyond the position of equilibrium in association with a maximum residual righting lever of at least 0.1 metre within the 20 degrees range; the area under the curve within this range shall not be less than 0.0175 metre radians. Unprotected openings shall not be immersed within this range unless the space concerned is assumed to be flooded; within this range, the immersion of any of the openings listed in subparagraph (a) and other openings capable of being closed watertight may be permitted;

• (d) a qualified person shall be satisfied that the stability is sufficient during intermediate stages of flooding;

• (e) equalisation arrangements requiring mechanical aids such as valves or cross-levelling pipes, if fitted, shall not be considered for the purpose of reducing an angle of heel or attaining the minimum range of residual stability to meet the requirements of subparagraphs (a), (b) and (c) and sufficient residual stability shall be maintained during all stages where equalisation is used; spaces which are linked by ducts of a large cross-sectional area may be considered to be common.

• (4) The requirements of paragraph (1) shall be confirmed by calculations which take into consideration the design characteristics of the ship, the arrangements, configurations and contents of the damaged compartments; and the distribution, specific gravities and the free surface effect of liquids. The calculations shall be based on the following:

• (a) account shall be taken of any empty or partially filled tank, the specific gravity of cargoes carried, as well as any outflow of liquids from damaged compartments;

• (b) the permeabilities assumed for spaces flooded as a result of damage shall be as follows:

	Spaces	Permeabilities
	appropriated to stores	0.60
	occupied by accommodation	0.95
	occupied by machinery	0.85
	voids	0.95
	intended for consumable liquids	0 to 0.95*
	intended for other liquids	0 to 0.95*

*the permeability of partially filled compartments shall be consistent with the amount of liquid carried in the compartment; whenever damage penetrates a tank containing liquids, it shall be assumed that the contents are completely lost from that compartment and replaced by salt water up to the level of the final plane of equilibrium;

• (c) the buoyancy of any superstructure directly above the side damage shall be disregarded; the unflooded parts of superstructures beyond the extent of damage, however, may be taken into consideration provided that they are separated from the damaged space by watertight bulkheads and the requirements of paragraph (3)(a) in respect of these intact spaces are complied with; hinged watertight doors may be acceptable in watertight bulkheads in the superstructure;

• (d) the free surface effect shall be calculated at an angle of heel of 5 degrees for each individual compartment; a qualified person may require or allow the free surface corrections to be calculated at an angle of heel greater than 5 degrees for partially filled tanks; and

• (e) in calculating the effect of free surfaces of consumable liquids it shall be assumed that, for each type of liquid at least one transverse pair or a single centreline tank has a 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.

• (5) The master of every oil tanker to which this Regulation applies, and the person in charge of a non-self-propelled oil tanker to which these Regulations apply shall be supplied in an approved form with—

• (a) information relative to loading and distribution of cargo necessary to ensure compliance with the provisions of this Regulation, and

• (b) data on the ability of the ship to comply with damage stability criteria as determined by this Regulation, including the effect of relaxations that may have been allowed under paragraph (1)(c).

• (6) For oil tankers of 20,000 tonnes deadweight and above delivered on or after 6 July 1996, the damage assumptions prescribed in paragraph (2)(b) shall be supplemented by the following assumed bottom raking damage:

• (a) longitudinal extent:

• (i) ships of 75,000 tonnes deadweight and above:

0.6L measured from the forward perpendicular;

• (ii) ships of less than 75,000 tonnes deadweight:

0.4L measured from the forward perpendicular;

• (b) transverse extent: B/3 anywhere in the bottom;

• (c) vertical extent: breach of the outer hull.

Slop tanks

• (2)
• (a) Adequate means shall be provided for cleaning the cargo tanks and transferring the dirty ballast residue and tank washings from the cargo tanks into a slop tank of a type approved by a qualified person.

• (b) In this system arrangements shall be provided to transfer the oily waste into a slop tank or combination of slop tanks in such a way that any effluent discharge into the sea will be such as to comply with Regulation 34.

• (c) The arrangements of the slop tank or combination of slop tanks shall have a capacity necessary to retain the slop generated by tank washings, oil residues and dirty ballast residues. The total capacity of the slop tank or tanks shall not be less than 3 per cent of the oil carrying capacity of the ship, except that a qualified person may accept—

• (i) 2 per cent for such oil tankers where the tank washing arrangements are such that once the slop tank or tanks are charged with washing water, this water is sufficient for tank washing and, where applicable, for providing the driving fluid for eductors, without the introduction of additional water into the system,

• (ii) 2 per cent where segregated ballast tanks or dedicated clean ballast tanks are provided in accordance with Regulation 18 or where a cargo tank cleaning system using crude oil washing is fitted in accordance with Regulation 4; such capacity may be further reduced to 1.5 per cent for such oil tankers where the tank washing arrangements are such that once the slop tank or tanks are charged with washing water, this water is sufficient for tank washing and, where applicable, for providing the driving fluid for eductors, without the introduction of additional water into the system, and

• (iii) 1 per cent for combination carriers where oil cargo is only carried in tanks with smooth walls; such capacity may be further reduced to 0.8 per cent where the tank washing arrangements are such that once the slop tank or tanks are charged with washing water, this water is sufficient for tank washing and, where applicable, for providing the driving fluid for eductors, without the introduction of additional water into the system.

• (d) Slop tanks shall be so designed particularly in respect of the position of inlets, outlets, baffles or weirs where fitted, so as to avoid excessive turbulence and entrainment of oil or emulsion with the water.

• (3) Oil tankers of 70,000 tonnes deadweight and above delivered after 31 December 1979, shall be provided with at least 2 slop tanks.

Pumping, piping and discharge arrangement

• (2) In every oil tanker of 150 gross tonnage and above, pipelines for the discharge to the sea of ballast water or oil contaminated water from cargo tank areas which may be permitted under Regulation 34 shall be led to the open deck or to the ship’s side above the waterline in the deepest ballast condition. Different piping arrangements to permit operation in the manner permitted in paragraph (6) may be accepted.

• (3) In oil tankers of 150 gross tonnage and above delivered after 31 December 1979, means shall be provided for stopping the discharge into the sea of ballast water or oil contaminated water from cargo tank areas, other than those discharges below the waterline permitted under paragraph (6), from a position on the upper deck or above located so that

• (a) the manifold in use referred to in paragraph (1), and

• (b) the discharge to the sea from the pipelines referred to in paragraph (2),

may be visually observed. Means for stopping the discharge need not be provided at the observation position if a positive communication system such as a telephone or radio system is provided between the observation position and the discharge control position.

• (4) Every oil tanker delivered after 1 June 1982, that is required to be provided with segregated ballast tanks or fitted with a crude oil washing system, shall comply with the following requirements:

• (a) it shall be equipped with oil piping so designed and installed that oil retention in the lines is minimised;

• (b) means shall be provided to drain all cargo pumps and all oil lines at the completion of cargo discharge, where necessary by connection to a stripping device;

• (c) the line and pump draining shall be capable of being discharged both ashore and to a cargo tank or a slop tank;

• (d) for discharge ashore, a special small diameter line shall be provided and shall be connected outboard of the ship’s manifold valves.

• (5) Every oil tanker delivered on or before 1 June 1982, that is required to be provided with segregated ballast tanks, or to be fitted with a crude oil washing system, or to operate with dedicated clean ballast tanks, shall comply with the provisions of paragraph (4)(b).

• (6) On every oil tanker the discharge of ballast water or oil contaminated water from cargo tank areas shall take place above the waterline, except as follows:

• (a) segregated ballast and clean ballast may be discharged below the waterline—

• (i) in ports or at offshore terminals,

• (ii) at sea by gravity, or

• (iii) at sea by pumps if the ballast water exchange is performed under the provisions of regulation D-1.1 of the International Convention for the Control and Management of Ships’ Ballast Water and Sediments;

but only if the surface of the ballast water has been examined immediately before the discharge to ensure that no contamination with oil has taken place;

• (b) oil tankers delivered on or before 31 December 1979, which, without modification, are not capable of discharging segregated ballast above the waterline may discharge segregated ballast below the waterline at sea; but only if the surface of the ballast water has been examined immediately before the discharge to ensure that no contamination with oil has taken place;

• (c) oil tankers delivered on or before 1 June 1982, operating with dedicated clean ballast tanks, which without modification are not capable of discharging ballast water from dedicated clean ballast tanks above the waterline, may discharge this ballast below the waterline provided that the discharge of the ballast water is supervised in accordance with Regulation 18(8)(c);

• (d) on every oil tanker at sea, dirty ballast water or oil contaminated water from tanks in the cargo area, other than slop tanks, may be discharged by gravity below the waterline, provided that sufficient time has elapsed in order to allow for a separation of oil and water to have taken place and the ballast water has been examined immediately before the discharge with an oil and water interface detector referred to in Regulation 32 in order to ensure that the height of the interface is such that the discharge does not involve any increased risk of harm to the marine environment;

• (e) on oil tankers delivered on or before 31 December 1979, that are at sea, dirty ballast water or oil contaminated water from cargo tank areas may be discharged below the waterline, subsequent to or in lieu of the discharge by the method referred to in subparagraph (d), but only if—

• (i) a part of the flow of such water is led through permanent piping to a readily accessible location on the upper deck or above where it may be visually observed during the discharge operation, and

• (ii) such part flow arrangements comply with the requirements established by a qualified person, which shall contain at least all the provisions of the Specifications for the Design, Installation and Operation of a Part Flow System for Control of Overboard Discharges adopted by the Organization;

• (7)
• (a) Every oil tanker of 150 gross tonnage and above delivered on or after 1 January 2010, which has installed a sea chest that is permanently connected to the cargo pipeline system, shall be equipped with both a sea chest valve and an inboard isolation valve.

• (b) In addition to these valves, the sea chest shall be capable of isolation from the cargo piping system whilst the tanker is loading, transporting, or discharging cargo by use of a positive means that is to the satisfaction of the Minister.

• (c) Such a positive means is a facility that is installed in the pipeline system in order to prevent, under all circumstances, the section of pipeline between the sea chest valve and the inboard valve being filled with cargo.

Chapter 2 Equipment

Oil discharge monitoring and control system

• (2)
• (a) Every oil tanker shall be fitted with an oil discharge monitoring and control system, the design and installation of which is in compliance with the specification recommended by the Organization and has been approved by the Minister.

• (b) The system shall be fitted with a recording device to provide a continuous record of the discharge in litres per nautical mile and total quantity discharged, or the oil content and rate of discharge. This record shall be identifiable as to time and date and shall be kept for at least three years.

• (c) The oil discharge monitor and control system shall come into operation when there is any discharge of effluent into the sea and shall be such as will ensure that any discharge of oily mixture is automatically stopped when the instantaneous rate of discharge of oil exceeds that permitted by Regulation 34.

• (d) Any failure of this monitoring and control system shall stop the discharge and be noted in the Oil Record Book.

• (e) In the event of failure of the oil discharge monitoring and control system, a manually operated alternative method may be used, but the defective unit shall be made operable as soon as possible.

• (f) Subject to allowance by the port State authority a tanker with a defective oil discharge monitoring and control system may undertake one ballast voyage before proceeding to a repair port.

• (3) The oil discharge monitoring and control system shall be designed and installed in compliance with the Guidelines and Specifications for Oil Discharge Monitoring and Control Systems for Oil Tankers developed by the Organization and approved by the Minister.

• (4) Instructions as to the operation of the system shall be in accordance with an operational manual approved by the Minister. They shall cover manual as well as automatic operations and shall be intended to ensure that at no time shall oil be discharged except in compliance with the conditions specified in Regulation 34.

Oil and water interface detector

• (2) For the purposes of this Regulation, regard shall be had to the Specifications for Oil/Water Interface Detectors adopted by the Organization by resolution MEPC.5(XIII).

Crude oil washing requirements

• (2) Crude oil washing installation and associated equipment and arrangements shall comply with the Specifications for the Design, Operation and Control of Crude Oil Washing Systems adopted by the International Conference on Tanker Safety and Pollution Prevention, 1978, in resolution 15 and as may be revised by the Organization. When a ship is not required, in accordance with paragraph (1), to be, but is equipped with crude oil washing equipment, it shall comply with the safety aspects of the above mentioned Specifications.

• (3) Every crude oil washing system required to be provided in accordance with Regulation 19(7) shall comply with the requirements of this Regulation.

Chapter 3 Control of operational discharge of oil in cargo area of oil tankers

Control of discharge of oil (Part 4)

• (a) the tanker is not within a special area;

• (b) the tanker is more than 50 nautical miles from the nearest land;

• (c) the tanker is proceeding en route;

• (d) the instantaneous rate of discharge of oil content does not exceed 30 litres per nautical mile;

• (e) the total quantity of oil discharged into the sea does not exceed—

• (i) for tankers delivered on or before 31 December 1979, 1/15,000 of the total quantity of the particular cargo of which the residue formed a part, and