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81 APPENDIX C IMO STABILITY-RELATED REGULATIONS The International Maritime Organization (IMO)23 is an agency of the United Nations (UN) tasked with enhancing maritime safety and protecting the marine environment on a worldwide basis. Headquartered in London, IMO holds annual meetings to review new regulations and discuss maritime matters. Its stated purpose is to foster cooperation among governments in matters that affect shipping and to encourage and adopt the best possible standards in areas such as marine safety, navigation, and pollution control. IMO membership is based on nation states, of which the U.S. Coast Guard (USCG) represents the United States. IMO is organized into several committees, with the Maritime Safety Committee (MSC) as the highest technical body. There are multiple subcommittees assisting the work of the MSC, including the Ship Design and Construction (SDC) subcommittee, which promulgates regulations related to vessel stability. Many of these regulations cover the same types of vessels as those covered by 46 Code of Federal Regulations (CFR), Subchapter S. USCG is an active IMO participant, usually playing a significant role in its rulemaking process, so the IMO regulations generally reflect USCG opinions on a particular topic. International Code on Intact Stability (2008) In a similar manner to the USCG consolidation of most of its stability regulations into Subchapter S, IMO has consolidated stability regulations into the International Code on Intact Stability (IS) Code that includes a wide variety of vessels. The most recent version was issued in 2008 (adopted by IMO Resolution MSC.267 (85), December 2008). Amendments were adopted 23 For additional information on IMO, see the following: http://www.imo.org/en/About/Pages/Default.aspx.
82 in 2011 (MSC.319 (89)); 2015 (MSC.398 (95)); and 2016 MSC.413 (97)), (MSC.414 (97)), and MSC.415 (97)). It is an intact stability code and does not address stability requirements for damaged vessels that are dealt with by other IMO documents, such as the International Convention for the Safety of Life at Sea (SOLAS), Chapter II-1, Part B, and the Convention for Prevention of Pollution from Ships (MARPOL). Other IMO codes, such as the Grain Code, International Bulk Chemical (IBC) Code, and International Ships Carrying Liquefied Gases in Bulk (IGC) Code, exist and are applicable to specialized vessels. While these other codes contain sections referring to stability that pertain to specialized vessel types or cargo, most of these special codes refer back to the IS Code for actual stability requirements. The types of vessels for which the IS Code is applicable include: ï· Cargo ships (which under the IMO includes tankers), ï· Cargo ships carrying timber cargoes, ï· Passenger ships, ï· Fishing vessels, ï· Special purpose ships, ï· Offshore supply vessels, ï· Mobile offshore drilling units, ï· Pontoons (deck cargo ocean barges), and ï· Cargo ships carrying containers on deck and container ships. This list covers most commercial vessels that are capable of ocean passage. Some may be coastal vessels, but the IS Code is not generally applicable to small boats, inland or near coast vessels, coastal and inland barges, and tug boats. When reviewing and updating IMO stability regulations, member delegations are assisted by academic, design, and operating personnel with specific areas of expertise, and member states are able to fund research at a significant level. These are all advantages that could be made available to U.S. Flag vessels if they sought to incorporate the IS Code, and USCG would not then have to independently develop its own regulations.
83 There is ongoing work to address dynamic stability in the IS Code beyond the simple advisory notes, and USCG is encouraged to continue these efforts. Recognizing there are many difficulties in developing realistic processes to carry out these stability calculations, dynamic stability appears to model ship survival in extreme wind and sea conditions more realistically than simple intact stability. The IS Code, outlined in the following section, is comprehensive; contains much of what is in 46 CFR, Subchapter S; and could be a source for updates to Subchapter S for applicable vessels. Overview of Stability Regulations in the IS Code The IS Code is divided into several parts. 1. Part A is mandatory and has the following chapters: a. Chapter 2 contains General Criteria applicable to all ships covered by the IS Code and contains two key sections: i. Criteria on righting lever curve properties (basic intact GM and righting lever criteria). ii. Severe wind and rolling criterion (weather criterion). b. Chapter 3 contains Special Criteria for Certain Types of Ships, including passenger ships, oil tankers of 5,000 dwt and above, cargo ships carrying timber deck cargoes, cargo ships carrying grain in bulk, and high speed craft. 2. Part B includes Recommendations for Certain Types of Ships and offers Additional Guidelines. These are recommendations for additional stability standards and are not mandatory. a. Chapter 2 contains recommended stability requirements for fishing vessels, pontoons (barges), container ships greater than 100 m, offshore supply vessels, special purpose ships, and mobile offshore drilling units (MODUs). b. Other chapters provide guidance on the following topics: i. Preparing stability information. ii. Guidance for stability instruments (loading programs). iii. Operational provisions against capsizing. iv. Icing conditions. v. Considerations for watertight and weathertight integrity. vi. Determination of lightship parameters. vii. Detailed guidance on inclining test. viii. Recommendations for fishing vessels in icing conditions.
