MARITIME SAFETY COMMITTEE

80th session

Agenda item 6

　

　

1 The Committee, at its seventy-ninth session, considered the goal-based new ship construction standards. The report of the working group established during that session was only presented to the plenary. The note of the chairman of the working group was submitted to MSC 80 (MSC 80/6). At that session of the Committee, Japan expressed its fundamental opinion, as is reported in paragraph 6.20 of document MSC 79/23.

　

　

2 Japan is of the opinion that goal-based new ship construction standards should be applicable to all types of new ship. It should be noted that, in IMO, the term "all ships" usually means all existing and new ships. Therefore, the terms "all ships" and "all types of ship" should be carefully used and differentiated.

　

3 Japan supports the general agreement within the working group that Tier I should more appropriately be considered as "goals" rather than "safety objectives" (see latter part of paragraph 9 of MSC 80/6). Therefore, Japan is of the opinion that Tier I should include only clear goals. In this connection, the first draft of the standards contained in annex 2 of document MSC 80/6 shall be further considered as a whole.

　

4 Japan also supports the general agreement of the working group that Tier II should apply to all types of new ships (see the first sentence of paragraph 15 of document MSC 80/6). Tier II of the standards shall be developed based on this agreement and shall not be for any particular type of ship.

　

　

5 Japan believes that Tier I of the standards should contain the goals of construction of new ships and goals of safety and marine environmental protection in regard to the new ship construction, and that the goals may contain conditions.

　

6 Japan also believes that Tier II should contain explanations and specifications of the conditions which lie in Tier I and fundamental requirements of new ship construction strength to achieve the goals specified in Tier I.

　

7 The conditions which should be specified in Tier II are:

　

8 The fundamental requirements for strength of ships are:

　

9 Japan proposes drafts for Tier I and Tier II of the standards as set out in the annex to this document. These drafts have been developed based on the opinion expressed in paragraphs 3 to 8 above, taking into account the draft provided in document MSC 80/6.

　

　

10 Japan is of the opinion that special consideration should be given to fatigue strength. The fatigue strength is dominated by the long-term accumulation of working loads throughout the ship's service period. Being quite different from ultimate strength, a small number of extreme loads do not connect with fatigue strength directly. This means that the fatigue strength is different from yield strength, buckling strength or ultimate strength.

　

11 It is, therefore, appropriate that a ship's fatigue strength should be designed in accordance with "suitable safety margin" and "individual environmental condition", which, unless otherwise specifically stated, shall be based on the statistics of actual operating pattern in principle. It should be noted that any ship satisfying worldwide fatigue design condition has been guaranteed to enter into the severest sea area, e. g., North Atlantic, when the design condition to the ship covers one of the subjected worldwide operating patterns, within a reasonable period for ship's life.

　

12 According to rough estimates for a crude oil tanker with a designed fatigue life of 25 years in the North Atlantic, the equivalent fatigue life of the subject tanker is 50 years and 75 years in the real worldwide and Persian Gulf-Far East operating patterns, respectively. The actual fatigue life could be longer than these expectations as a result of adequate maintenance. As pointed out, the fatigue life is so sensitive to environmental conditions that unreasonably fixed environmental conditions can result in excessive margin or even unbreakable design deadlock, depending on the ship types and sizes. The impractical requirements do bring the shipping industry into significant inflexibility. The structural safety of every ship can rationally be ensured without unified and/or unrealistic design environmental conditions.

　

13 Japan also supports the idea presented in paragraph 19 of document MSC 80/6 that "corrosion addition" and "coating life" should not be two separate functional requirements and instead should be included in one requirement referred to as "corrosion control". Japan is of the opinion that "corrosion control" is an important measure for safety, which should include selection of materials, corrosion addition, coating requirements with coating life and coating maintenance. In other words, the requirement for corrosion control should be fulfilled by any combination of such sub-requirements.

　

　

14 The Committee is invited to consider the proposed draft Tier I and Tier II of the goal-based new ship construction standards, as set out in the annex to this document, and take action as appropriate.

　

　

　

 Ships shall be designed and constructed for a specified design life to be safe and environmentally friendly, when properly operated and maintained under the envisaged operating and environmental conditions, intact and foreseeable damage conditions throughout their life.

　

　

　

 In order to achieve the goals specified in Tier I, the following key requirements shall be satisfied.

　

　

 Design life shall be specified for each ship in order to develop appropriate design. Design life is the nominal period that the ship is assumed to be exposed to operating and environmental conditions. However, the ship's actual life may be longer or shorter than the design life depending on the actual conditions of the structure of the ships under the actual operating and environmental conditions. Unless specifically stated otherwise, the design life shall be 25 years. A document showing the design life shall be kept on board throughout the life of the ship.

　

　

 Design environmental conditions shall be specified for each ship in order to develop an appropriate design for the ship. The environmental condition shall be determined taking into account the foreseeable voyage routes and operating conditions of the ship. The document showing the design environmental condition shall be kept on board throughout the life of the ship. For ships intended for operation in unspecified sea area(s), foreseeable North Atlantic environmental conditions and its long-term sea state scatter diagram shall be used for yielding, buckling and ultimate strength assessments, and world-wide environmental conditions and its long-term sea state scatter diagram shall be used for fatigue strength assessment. For ships intended for operation in specified sea area(s), the foreseeable environmental conditions and long-term sea state scatter diagram of the sea area(s) shall be used for all strength assessments of the ship.