1 The purpose of these Revised Interim Guidelines,
hereunder referred to as "the Guidelines’’, is to provide
an international standard for the evaluation and approval of alternative
methods of design and construction of oil tankers under regulation 13F(5) of Annex I
of MARPOL 73/78.
2 The basic philosophy of the Guidelines is to
compare the oil outflow performance in case of collision or stranding
of an alternative tanker design to that of reference double-hull designs
complying with regulation 13F(3) on the basis of a calculated pollution-prevention
index.
3 The oil outflow performance of double-hull tankers
which comply with regulation 13F(3) may be different. The longitudinal
subdivision of the cargo tanks has a major influence on the oil outflow
in case of inner hull penetration. The selected reference double-hull
designs exhibit a favourable oil outflow performance.
4 The calculation of oil outflow is based on the
probabilistic methodology and best available tanker accident damage
statistics. Reappraisal of the Guidelines may be appropriate when
more information on tanker accident damage has become available and
more experience with the application of these Guidelines has been
gained.
5 Falling tides will have an adverse effect on
oil outflow from a stranded tanker and the Guidelines take account
of this. The tide values specified in section 5 represent realistic
average tidal changes which have been chosen to identify the influence
of tidal changes on the oil outflow in case of stranding.