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Suggested Citation:"Summary." National Academies of Sciences, Engineering, and Medicine. 2019. Review and Update of U.S. Coast Guard Vessel Stability Regulations and Guidance. Washington, DC: The National Academies Press. doi: 10.17226/25565.
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Page 1
Page 2
Suggested Citation:"Summary." National Academies of Sciences, Engineering, and Medicine. 2019. Review and Update of U.S. Coast Guard Vessel Stability Regulations and Guidance. Washington, DC: The National Academies Press. doi: 10.17226/25565.
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Page 2
Page 3
Suggested Citation:"Summary." National Academies of Sciences, Engineering, and Medicine. 2019. Review and Update of U.S. Coast Guard Vessel Stability Regulations and Guidance. Washington, DC: The National Academies Press. doi: 10.17226/25565.
×
Page 3
Page 4
Suggested Citation:"Summary." National Academies of Sciences, Engineering, and Medicine. 2019. Review and Update of U.S. Coast Guard Vessel Stability Regulations and Guidance. Washington, DC: The National Academies Press. doi: 10.17226/25565.
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Page 4

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PREPUBLICATION COPY—Uncorrected Proofs 1 Summary The U.S. Coast Guard (USCG) has safety regulatory jurisdiction over vessels registered in the United States, and an important part of this jursdiction is to ensure these vessels remain upright as they encounter both anticipated and unexpected loading, operating, and weather (wind and wave) conditions. The USCG has made major changes to its stability regulations over the past 30 years, most notably by consolidating the majority of the regulations in a single subchapter— Subchapter S of Title 46 of the Code of Federal Regulations (46 CFR) Chapter I. As a signatory to SOLAS (International Convention for the Safety of Life at Sea), the USCG applies SOLAS damage stability regulations and intact stability—or IS Code (Intact Stability Code)—to U.S. flag vessels with international certificates. Stability standards have been improved over time, but despite these improvements, the USCG remains interested in keeping the regulations updated based on the latest technical knowledge, aligned with international standards, and organized and presented in a manner that facilitates compliance. The USCG commissioned an earlier National Academies of Sciences, Engineering, and Medicine (the National Academies) study to identify options for improving the vessel stability regulations contained in Subchapter S. The report from that study was issued on September 12, 2018.4 Shortly after that study, the USCG asked for this second National Academies study consisting of several follow-on assignments. Specifically, the USCG requested (1) a review of candidate improvements to stability regulations that exist outside Subchapter S (particularly Subchapter T),5 with a focus on vessels that operate inside the Boundary Lines; (2) an examination of opportunities to improve any policy and other guidance documents that may supplement the Subchapters S and T regulations; and (3) a possible methodology for prioritizing improvements to the Subchapter S stability regulations as suggested by the committee’s Phase 1 report.6 In addition, the USCG asked the committee to consider any new statutory requirements that may affect USCG priorities with regard to vessel stability regulations. Indeed, shortly after the study commenced, Congress passed the Save Our Seas Act of 2018 (Public Law 115-265),7 which—prompted by the sinking of the SS El Faro—mandated that the USCG take action on several items, including (1) establishing recordkeeping requirements for all incremental weight changes to freight vessels over time and (2) reviewing the effectiveness of U.S. regulations, international conventions, recognized organizations’ class rules, and USCG technical policy regarding intact and damage stability requirements. At the study committee’s first meeting, the USCG asked for input on how it should respond to these two statutory provisions, along with the three other requests that followed from the first study as previously noted. This summary takes each of the five task items in turn, starting with the two requests from the Save Our Seas Act. In two instances, the text highlights a finding and recommendation that the committee believes warrants special attention by the USCG. 4 See http://www.trb.org/Policy/Blurbs/178088.aspx. 5 Subchapter S of 46 CFR contains vessel stability requirements for most vessels used in commercial passenger and cargo service; Subchapter T also contains stability requirements that apply to certain small, inspected passenger vessels; and Subchapter C applies to certain uninspected vessels (primarily commercial fishing industry vessels). 6 Phase 1 letter report: http://www.trb.org/Main/Blurbs/178088.aspx. 7 See https://www.congress.gov/bill/115th-congress/senate-bill/3508.

PREPUBLICATION COPY—Uncorrected Proofs 2 LIGHTSHIP WEIGHT RECORDKEEPING AND TRACKING Currently, the only inspected vessels that the USCG requires tracking of lightship weight changes are passenger vessels with SOLAS certificates and towing vessels subject to Subchapter M requirements. The USCG requires that vessel operators report any changes to their lightship characteristics that arise from vessel modifications and retain these records in a vessel’s stability letter to know when updated stability calculations, a deadweight survey, or an inclining test may be needed in the future. Although recently the USCG had proposed requirements for lightship weight tracking and periodic stability testing for a wider range of passenger and freight vessels, it has withdrawn these proposals because of concern about the high cost of implementation (especially for periodic testing) and the absence of casualty data indicating that changes in lightship weight have caused vessel losses. Analyses in this report suggest that passenger vessels, much more than freight vessels, are subject to degradations in stability as a result of increases in lightship weight. The passenger vessels would appear to be more pressing candidates for lightship weight- tracking programs than freight vessels, whose lightship weights tend to account for a smaller percentage of vessel-loaded displacement. The sensitivity analysis performed by the committee indicates that weight changes up to the traditional threshold of 2% of lightship weight pose little risk to the stability compliance of most freight vessels. By comparison, the report’s sensitivity analysis shows passenger vessels are frequently more sensitive to weight change than freight vessels, since passenger vessels, particularly smaller ones, tend to operate with less stability margin. The periodic updating of passenger spaces and equipment that occurs over time can be expected to create “weight creep” that can affect the ability of the vessel to comply with stability requirements. In addition, maximum draft may not be marked on the hull of small passenger vessels, meaning that changes in lightship weight (e.g., 2% to 5%) that are large enough to affect stability compliance may not be readily apparent to the crew and operator. Vessel operations in fresh, brackish, and salt water—each having different densities—can obscure the fact that some draft changes are caused by lightship weight changes. A lightship-tracking program can therefore be particularly important for passenger vessels. To be effective in gauging stability impacts, it is important that a lightship-tracking program have certain characteristics that ensure both timely and accurate data recording and a high degree of usability. Although an accurate recording of weight changes is essential, the timing of when incremental changes in weight should be recorded will depend in large part on the vessel type and its stability sensitivity to changes in lightship weight. In general, freight vessels will need to record weight changes far less often than passenger vessels and only when larger weights are added, moved, or removed. For any vessel type, an important consideration in designing and implementing a weight- tracking program is its ease of use by crew and onshore personnel. In this regard, a program that has complexity suited to the levels of stability training and knowledge of the crew will be essential to ensuring the program can and will be used as needed to ensure that weight gains that create stability risks are monitored and assessed as needed. Likewise, to facilitate use, the program’s format (e.g., paper- or computer-based) and operations will need to be familiar to the vessel’s crew and other users and compatible with other technologies and practices commonly used in operating the vessel safely.

PREPUBLICATION COPY—Uncorrected Proofs 3 DETERMINING THE EFFECTIVENESS OF STABILITY REGULATIONS The USCG asked the committee to advise on a methodology for conducting a review of the effectiveness of U.S. regulations and guidance about intact and damage stability standards under Subchapter S. As a starting point for evaluating effectiveness, the USCG might want to focus on those casualties that cause loss of life or significant injury or property loss, data from the United States, as well as from other countries, could be useful for this purpose. An understanding of the causes of these more serious stability-related incidents will help identify weaknesses in the requirements that have the greatest impact on their overall effectiveness, while pointing to opportunities for cost-effective regulatory enhancements. In addition to examining trends in casualties related to stability losses, a review of regulatory qualities such as ease of use, technical accuracy, and scope of applicability can provide insight into the likelihood that a regulation is having the desired effectiveness. For example, assessments of the number of policy documents required to support a regulation can be indicative of its clarity and usability, as a large number of required documents could suggest a need for clarity improvements. Various technical studies are also needed for the USCG to review the effectiveness of its stability standards. For example, because weight data are essential to making stability calculations, a sensitivity study of the impact of inaccurate or uncertain weight data on vessel stability calculations would be helpful in understanding when there is need to improve the accuracy of such data. The USCG may want to follow up on International Maritime Organization (IMO) studies of cargo container weights coupled with a study of lightship weight data for vessels prone to low stability margins to determine when and to what extent inaccurate weight data can create a stability risk for different vessel types. Completing a systematic and thorough analysis of the differences in the requirements of the various intact and damage stability standards (e.g., IMO, Class, Subchapter S) would provide a basis for assessing and measuring technical effectiveness among the various stability-related regulatory regimes. IMPROVING STABILITY REQUIREMENTS OUTSIDE SUBCHAPTER S The existing Subchapter T stability standards (Part 178 Intact, Part 179 Subdivision) appear to be generally well suited to the domestic passenger vessels they cover, and the transition between when a vessel can use the simplified intact stability tests and the simplified subdivision calculations in Subchapter T as opposed to the stability standards in 46 CFR Subchapter S is adequately reasoned. The report, however, does point to instances in which the current Subchapter T regulations could be updated to improve clarity and usability (as outlined in Chapter 5) and where it may be desirable to add stability standards for some of the smaller passenger vessels (certified for carrying not more than 49 persons) that are covered by this subchapter to address stability hazards unique to these vessels. The committee believes that the USCG should examine whether supplemental regulation in Subchapter T is warranted to address the flooding risks associated with open vessels that lack requirements for minimum freeboard, and whether such vessels should be required to remain afloat and upright when swamped. In addition, the USCG should examine whether subdivision requirements are warranted in Subchapter T to protect against uncontrolled local flooding following the failure of a sea or hull connection. In particular, candidate vessel types for such supplemental standards are those that have open, well, or large cockpit designs and those that can carry up to 49 persons that have no subdivision requirements.

PREPUBLICATION COPY—Uncorrected Proofs 4 OPPORTUNITIES TO IMPROVE POLICY AND OTHER GUIDANCE DOCUMENTS As part of the committee’s work for this report, the USCG requested a review of USCG policy documents following the criteria recommended by the committee’s Phase 1 report8—that the USCG establish a sustainable, repeatable, ongoing, and transparent process to publish, review, and update its policy documents. A detailed review of all relevant policy documents would have exceeded the time and resources available for the study. However, after a limited review of these documents, the committee believes the USCG could consider several actions. An important action would be to review and consolidate all of the USCG’s stability policy decisions. In the first phase of this study, the committee recommended that the USCG establish a sustainable, repeatable, ongoing, and transparent process to publish, review, and update its policy documents. The more than 38 USCG stability policy documents located and reviewed by the committee for this phase of the study were found on multiple websites and also included some documents not available online. The multiple website locations, each having different degrees of searchability (from none to functional), can make it difficult for both the marine community and USCG personnel to find and use the guidance effectively. Consolidating USCG stability policy decisions for a particular vessel type or class to a single document would be desirable for both users and USCG personnel. A review of four types of policy documents pertaining to Chapter S stability regulations—Navigation and Vessel Inspection Circulars (NVICs), Policy File Memorandums (PFMs), policy letters, and policy memoranda—suggests that some of the information and guidance in documents needs to be revisited and potentially modified or withdrawn. It would be desirable to undertake such a review and updating prior to any consolidation of documents and then repeat this process on a regular basis. A review of the document maintenance practices of other organizations suggests that such a review and updating process should be undertaken on an established schedule, with well-assigned responsibilities, and with transparent outputs. PRIORITIZATION METHODOLOGY FOR REGULATORY IMPROVEMENTS The committee’s first report provided a preliminary assessment of each part and subpart of Subchapter S that identified candidate updates or changes for consideration. For the current report, the USCG asked for suggestions on a methodology that could be used to prioritize these updates and changes. The committee therefore developed a methodology to prioritize changes on the basis of risk impact, ease of change or implementation, and clarity and harmony.9 To demonstrate the application of the risk ranking methodology, the committee applied it to the candidate changes identified in the Phase 1 report. For the top six priority regulation changes identified by the methodology, the rationale for their high ranking is explained. 8 Phase 1 letter report: http://www.trb.org/Main/Blurbs/178088.aspx. 9 Although the committee did not comment on how often the USCG should apply the methodology, one would expect that changes in ship technology (ship size and speed, number of passengers, reduced manning, autonomous operations) and operational environment (Arctic or highly environmentally sensitive areas) might trigger a reassessment.

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Review and Update of U.S. Coast Guard Vessel Stability Regulations and Guidance Get This Book
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U.S. Coast Guard (USCG) ship stability regulations governing the ability of a vessel to return to an upright position after being disturbed is the focus of a new TRB publication, Review and Update of U.S. Coast Guard Vessel Stability Regulations and Guidance. The authors advise the USCG on how it can make its stability regulations more usable and complete in meeting the requirements of different types of vessels and those vessels that have undergone weight changes that can affect their stability characteristics.

The USCG has safety regulatory jurisdiction over vessels registered in the United States. One of its oldest regulatory functions is to ensure these ships, boats, and other floating vessels remain upright as they encounter both expected and unexpected loading, operating, and weather conditions, including wind and wave conditions and unexpected failure of watertight integrity.

Stability standards have been improved over time - particularly in the past 30 years - and the USCG remains keenly interested in making sure the regulations are kept updated based on the latest technical knowledge, well aligned with international standards, and organized and presented in a manner that facilitates compliance and enforcement. The recommendations in the report are intended to further these aims. The USCG earlier commissioned a National Academies study to identify options for improving vessel stability regulations, and after receiving that study in September 2018, the USCG asked for this second study to provide more in-depth advice on applying these options.

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