Ships shall be designed with sufficient safety margins at net scantlings to withstand foreseeable environmental and operating conditions throughout their design life. Ships shall be inspected, surveyed, maintained and repaired to keep net scantlings throughout their actual life. Structural strength shall be assessed against excess deformation and all failure modes. Sufficient wastage margins shall be determined, taking into account the design life, usage of the space, the environmental conditions, coating, operation and maintenance, and added to net scantlings.

　

 Net scantlings and wastage margins of the main structural members shall be recorded and kept onboard throughout the life of the ship. In addition, actual thickness of main structural members obtained from periodical surveys and actual structural condition assessed from results of such surveys shall be recorded and kept onboard throughout the life of ship.

　

　

 Ships shall be designed against fatigue, taking into account the mean static stress and cyclic stress to prevent fatigue cracks which cause a loss of the function of the structural members.

　

　

 Ships shall be designed not to create immediate progressive damage to the ship's structure under accidental conditions, including flooding, collision and grounding, that are reasonably foreseeable for their type.

　

　

 Ships shall be designed to prevent the total collapse of the structure against foreseeable maximum extreme loads throughout their design life under the design environmental conditions. Ultimate strength calculations shall include ultimate hull girder capacity.

　

　

 Ships shall be designed, constructed and equipped to provide adequate means of access to all internal structures to facilitate overall and close-up inspections, thickness measurements and maintenance.

　

　

 Ships shall be designed presuming the proper maintenance for keeping the structural integrity against corrosion, wear down and fatigue. Such maintenance shall be prescribed at the design stage. Procedures for agreed maintenance^* shall be documented and kept on board of the ship throughout its life. Ships shall be designed and constructed to facilitate the maintenance.

　

　

 Ships shall be designed taking into account the operating conditions including safety navigation and loading, unloading, and ballasting. Such conditions^* shall be documented and kept on board of the ship throughout its life.

　

　

 Ships shall be built in accordance with controlled quality production standards.^* The ship construction quality procedures shall include, but not be limited to, specifications for material manufacturing, alignment, assembling, jointing and welding procedures, surface preparation and coating.

　

　

 Ships shall be designed under a reliable, controlled and transparent process, made accessible to the extent necessary to confirm the safety of the ship, with due consideration to intellectual property rights.

　

　

 A survey plan^* shall be developed for the life the ship, taking into account the type, design and actual construction. The survey plan shall be kept up-dated and kept on board throughout the life of the ship. The survey plan shall contain a set of requirements concerning inspection intervals necessary to maintain a ship within its design and construction limits, including fatigue, corrosion, structural strength and residual strength.

　

　

 Documented information on design life, operational and environmental conditions, structural strength including net scantlings, wastage margins, actual thickness and conditions of main structural members, maintenance procedures and survey plans shall be kept onboard and well known by the seafearers, the operator, the company and the owner, and this shall be available for surveyors when they survey the ship.

　

　

国際基準関連年表（船体構造関係）

　

1986　　IACS　縦強度（横断面係数）基準（就航中90%）（UR-S7）

1991.5　　IACS　縦強度統一規則UR-S11

1989　　エクソンバルディーズ号事故

1992.3　MEPC32　　13F、13G規則採択（93.7.1施行、13Gは95.7.6施行）

1992　　IACS船体検査統一規則UR-Z10.1&2（NKは93.7.1から実施）

1993.11　A18　　A.744（18）の採択（13G適用タンカーは95.7.6から強制化）

　ISMコード（A.741（18））の採択

1994.5　SOLASConf.3　　A.744（18）の強制化（SOLAS XI/2規則 1996.1.1施行）

　認定団体（RO）の承認要件（SOLAS XI/1規則）

　ISMコードの強制化（SOLAS IX章1998.7.1施行）

1995.11　A19　　バラスト専用タンクの塗装指針（A798（19））採択

1996.5　MSC66　　船体構造に関する船級規則の義務化（SOLAS II-1/3-1）

　バラスト専用タンクの塗装の強制化（SOLAS II-1/3-2）

1997.1　　ナホトカ号事故

1997.4　　RR74老朽船WG立ち上げ

1997.5　MSC68　　板厚衰耗限度の記載義務付けの日本提案（承認される）

1997.11　SOLAS.Conf.4　　バルクキャリアの安全性採択（SOLAS12章1999.7施行）

板厚衰耗限度の記載義務付け日本提案（タンカー）

1998.6　FSI6　　船体構造の健全性に関するPSCの強化の日本提案

1999.11　A21　　PSC手順書A787（19）の改正（船体構造の健全性に関するPSCの強化取り入れ）

1999.12　　エリカ号事故

2000.5　MSC73　　縦強度基準（Z＞90%）（日本提案）採択（2002.7発行）

2001.1　MEPC/CAS　　CAS WorkingGroup

2001.4　MEPC46　　SHタンカーフェーズアウト前倒し＆CAS採択

2002.11　　プレスティージ号事故

2003.5　MSC77　　縦強度評価のための板厚計測（ベルトゲージング）方法の採択

　

断面係数（Z）の規則要求値との比較

　

　

・新造時要求値（IACS-URS7、甲板側・底板側同じ値）

・新造時設計値

・就航後要求値（IACS-URS7、甲板側・底板側同じ値）

・事故時（26歳）の推定値（破断部調査結果より推定、甲板ロンジの脱落は考慮せず）

（参考）

・甲板ロンジ脱落（全24本中8本脱落）を考慮した推定値※

　

・新造時要求値（IACS-URS7、甲板側、底板側同じ値）

・新造時設計値

　

・就航後の要求値（IACS-URS7、甲板側、底板側同じ値）

・事故時（25歳）の推定値（1年前の板厚計測結果より）

　

・新造時要求値（IACS-URS7、甲板側、底板側同じ値）

・新造時設計値

・就航後要求値（IACS-URS7、甲板側、底板側同じ値）

・事故時（26歳）の推定値（1年前の板厚計測結果より）