1.1
Regulation
13F of Annex I of MARPOL 73/78 specifies structural requirements
for new tankers of 600 dwt and above, contracted on or after 6 July
1993. Paragraph (3) of the regulation requires tankers of 5,000 dwt
and above to be equipped with double hulls. Various detailed requirements
and permissible exceptions are given in the regulation.
Paragraph (5) of the regulation specifies that other designs
may be accepted as alternatives to double hull, provided they give
at least the same level of protection against oil pollution in the
event of collision or stranding and are approved in principle by the
Marine Environment Protection Committee (MEPC) based on Guidelines
developed by the Organization.
1.2 These Guidelines should be used to assess
the acceptability of alternative oil tanker designs of 5,000 dwt and
above with regard to the prevention of oil outflow in the event of
collision or stranding as specified in paragraph (5) of regulation
13F.
1.3 For any alternative design of an oil tanker
not satisfying regulation 13F(3) or (4), a study of the cargo oil
outflow performance should be carried out as specified in sections
4 through 6 of these Guidelines.
1.4 This study should cover the full range of
ship sizes with a minimum of four different ship sizes, unless the
approval is requested for only a limited range of vessel sizes. Data
for four reference double-hull designs are given in section 7.
1.5 Evaluation of the cargo oil outflow performance
of the proposed alternative design should be made by calculating the
pollution-prevention index E, as outlined in section 4 of these Guidelines.
1.6 The probabilistic methodology for the calculation
of oil outflow according to these Guidelines is based on available
tanker casualty statistics. With the collection of additional statistical
material, the damage density distribution functions specified in paragraph
5.2 should be periodically reviewed.
1.7 In principle, and as far as applicable, the
requirements of paragraphs (3)(d)-(f), (6) and (8) of regulation 13F
apply also to alternative designs. The requirements of paragraph (9)
of regulation 13F also applies to alternative designs. In addition,
it should be demonstrated by means of a risk analysis that the new
design under consideration provides an adequate safety level. Such
analysis should address any specific risks associated with the alternative
design and, if there are any, it should be demonstrated that safe
solutions exist to cope with them.