2.1 For combination carriers, a separate criterion
for the mean oil outflow parameter may be applied provided it is demonstrated
by calculations that the increased structural strength of the design
is providing for environmental protection at least equivalent to a
standard double hull oil tanker of the same size. The calculations
are to be to the satisfaction of the Administration.
2.2 These standard oil tankers shall comply with MARPOL 73/78, including the requirements relating
to width of wing-tanks and height of double bottom. The scantlings
of the standard tanker shall be as per the requirements for a tanker
of the same size as the combination carrier, and with the same loading
conditions, apart from the dry bulk conditions.
2.3 The calculations are to demonstrate the enhanced
strength of the double bottom and/or side structure of the combination
carrier sufficiently reduces the extent of damage, such that the oil
outflow performance of the combination carrier is comparable to that
of the standard oil tanker referred to above in terms of the extent
of damage and influence on oil outflow. The calculations are to include
a series of collision and/or grounding calculations by means of finite
element method (FEM) or other appropriate means. For each damage position
(each collision or grounding case) a development of dissipated plastic
deformation energy shall be evaluated. The collision calculations
shall be carried out assuming the combination carrier being the struck
ship at full load condition for different striking positions defined
by the drought differences to the striking ship.