ABSTRACT

After having reviewed very briefly the technical contents of OPA 90 and future IMO regulations, emphasis is laid on the influence of these regulations on the structural design of double hull oil tankers. Technical aspects specific to this type of vessels, in particular Suez Max: Tankers and VLCCs, are considered and examined in more detail. Some typical structural arrangements of double hull tankers are compared not only from design and also from construction and maintenance points of view.

2. US OIL POLLUTION ACT OF 1990 AND PENDING IMO LEGISLATION
2.1. US OPA 90

The part of the US OP A 90 which deals with the design of newbuildings and the time scale to phase out existing ships may be summarized as follows:

  • All newbuildings and/or major conversions of 5,000 gross tons and over, contracted on or after 30 June 1990 or delivered after 1 January 1994, must have double hulls, which means double side and double bottom.

  • All newbuildlings and/or major conversions under 5,000 gross tons contracted on or after 30 June 1990 or delivered after 1 January 1994, are required to have double containment systems.

  • Existing ships of 5,000 gross tons and over, withoutdouble hulls, are to be fitted with a double hull or phased out from 1995 until 2015, depending on their age and tonnage.

  • Existing ships under 5,000 gross tons are required to have double containment systems only after 1 January 2015. Based on the comments received from their national shipping community, the US Coast Guards will publish a set of rules applicable to double hulled tankers within the next months.

2.2.

Pending IMO Legislation International maritime community reacted to the US legislation and many alternatives have been proposed as substitute to double hulls.

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