Hong Kong Regulations

MERCHANT SHIPPING (PREVENTION OF OIL POLLUTION) REGULATIONS - REGULATION 27

Interpretation of Part V

(1) For the purposes of this Part "side and bottom damage" (船側及船底損
毀) and "hypothetical outflow of oil" (假設油類流出量) shall have the
following meanings-

   (a)  side and bottom damage shall be assumed to be damage having the
        dimensions described below caused to the side or bottom of the ship.
        In the case of bottom damage the dimensions to be assumed are those
        which relate to the position of damage, as described below.

        (i)    Side damage Longitudinal extent (1c): 1/3L2/3 or 14.5 metres,
               whichever is less Transverse extent

   (tc) :(inboard from the ship's side at right angles to the centre-line at
        the level corresponding to the assigned summer freeboard)
B/5 or 11.5 metres, whichever is less Vertical extent (vc): from the base line
upwards without limit

        (ii)   Bottom damage Position of Damage
For 0.3 L from the forward perpendicular of the ship Any other part of the
ship Longitudinal extent (1s): L/10 L/10 or 5 metres whichever is less
Transverse extent (ts): B/6 or 10 metres, whichever is less but not less than
5 metres 5 metres Vertical extent from the base line (vs): B/15 or 6 metres,
whichever is less

The symbols in brackets in the first column of the above table shall have the
meaning indicated in relation thereto, which shall apply for the purposes of
this Part of these Regulations.

   (b)  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 at all conceivable
        locations along the length of the ship to the extent as described in
        paragraph

(1)(a) of this regulation.

        (i)    for side damage:
Oc = Sigma Wi + Sigma KiCi                      (I)


        (ii)   for bottom damage:
Os + 1/3(Sigma ZiWi + Sigma ZiCi)            (II)
where: Wi = volume in cubic metres of a wing tank assumed to be breached by
the damage as described in paragraph (1)(a) of this regulation. Wi for a
segregated ballast tank may be taken as equal to zero. Ci = volume in cubic
metres of a centre tank assumed to be breached by the damage as described in
paragraph (1)(a) of this regulation. Ci for a segregated ballast tank may be
taken as equal to zero. Ki = 1-bi/tc when bi is equal to or greater than Tc,
Ki shall be taken as equal to zero. Zi = 1-hi/vs when hi is equal to or
greater than vs, Zi shall be taken as equal to zero. bi = minimum width in
metres of the wing tank 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 in metres of the double bottom
under consideration; where no double bottom is fitted hi shall be taken as
equal to zero. The symbols set out in this sub-paragraph shall have the
meanings assigned to them, which shall apply for the purposes of this Part of
these Regulations.

(1A) For the purpose of this Part, "new oil tanker" (新油輪) has the
meaning assigned to it by regulation 17(1). (L.N. 177 of 1991)

(2) Where a void space or segregated ballast tank of a length less than 1c as
defined in paragraph (1)(a)(i) of this regulation is located between wing oil
tanks, Oc in formula (I) set out in paragraph (1)(b) of this regulation 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 a collision the value of
the actual full volume of those tanks. 1i Si = 1 ____ 1c where 1i = length in
metres of void space or segregated ballast tank under consideration.

(3) (a) For the purpose of paragraph (1)(b) of this regulation account shall
be taken of double bottom tanks which are either empty or carrying clean water
only 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 shall be considered
        non-existent and the volume of the tanks above the area of the bottom
        damage shall be included in formula (II) set out in paragraph (1)(b)
        of this regulation 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 of hi
        provided such wells are not excessive in area and extend below the
        tank 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 to be equal to the double bottom height minus the well
        height.

   (d)  Piping serving suction 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 so as 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 whenever the tank contains oil cargo,
        except that they may be opened only to transfer cargo for trimming the
        ship.

(4) In the case where bottom damage simultaneously involves four centre 
tanks, the valve of Os may be calculated according to the formula.
Os = 1/4(Sigma ZiWi + Sigma ZiCi)                (III)


(5) (a) In the case of bottom damage, a reduced amount of oil outflow may be
assumed where a cargo transfer system is installed which has an emergency high
suction in each cargo tank capable of transferring from a breached tank or
tanks to segregated ballast tanks or to cargo tanks, if such tanks have
sufficient ullage, and if the cargo transfer system complies with the
following requirements-

        (i)    in two hours of operation it is capable of transferring oil
               equal to one half of the largest of the breached tanks
               involved;

        (ii)   the ballast or cargo tanks are available and capable of
               receiving such quantity; and

        (iii)  the pipes for such suction are installed at a height of not
               less than the vertical extent of the bottom damage vs.

   (b)  Where those requirements are satisfied, the calculation of Os shall be
        in accordance with formula (III) set out in paragraph (4) of this
        regulation.

"side and bottom damage" (船側及船底損毀) and "hypothetical outflow of
oil" (假設油類流 出量)

"new oil tanker" (新油輪)