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Saturday, March 24, 2018


In the aftermath of the ERIKA accident, Japan has proposed to IMO Amendments to the Enhanced Survey Requirements [Assembly Resolution A.744 (18)] on oil tankers over 10 years of age.

Japan justifies the proposal by the fact that oil tankers over a certain length with longitudinal strength members of a diminished thickness in the entire range of the hull, even if such diminution is within the allowable diminution limits, are susceptible to breaking into two due to the lack of the longitudinal strength of the hull girder.

Japan has proposed that for oil tankers of 130 m in length and over 10 years of age, the ship’s longitudinal strength should be evaluated by using the thickness of structural members measured during the renewal surveys. Such evaluation needs to be made initially by calculating the transverse sectional area of deck and bottom longitudinal structural members, and if the diminution of the section area of deck and bottom flanges exceeds 15% of the as-built value, then the options are to:

A/ reinforce the structural members to the minimum required value (85% and over the as-built area) or

B/ carry out the calculation of the section of transverse section of the ship’s hull girder, by using the actual thickness of the structural members as measured.

This matter was initially submitted to the IMO Sub-Committee on Design and Equipment and due to the full support is to be addressed by the IMO Marine Safety Committee.

In principle the issue is not new and it is practised by Classification Societies. The IACS standard diminution is not 15% but 10%. However, if the issue were to be added to the IMO Resolution A.744(18), then it would become a common practice for all tankers and not an optional assessment provided by Class. It is expected that MSC will adopt such an amendment as an urgent matter and with the request that it be enforced as soon as possible.  For further information, please contact