Review and Update of U.S. Coast Guard Vessel Stability Regulations and Guidance (2019) / Chapter Skim
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Pages 41-50
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From page 41... ...
Section 212 (b)
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From page 42... ...
42 USCG VESSEL STABILITY REGULATIONS AND GUIDANCE be addressed by the specific regulation or standard.1 There is a challenge too in estimating how observed safety outcomes, such as the number of casualties, would have changed in the absence of a regulation or standard (i.e., the counterfactual) when such an unregulated environment may not have existed for many years.
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From page 43... ...
EFFECTIVENESS OF CURRENT STABILITY REGULATIONS 43 technical documents, one might consider whether the regulations are based on static, quasi-static, or dynamic stability methods and whether they provide realistic and sufficient coverage of intact and damage vulnerabilities associated with vessel size and type. By examining a range of scenarios involving vessel types and sizes that have different susceptibilities to stability problems, such as a partial stability failure (excessive roll/acceleration, vessel heeled only)
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From page 44... ...
44 USCG VESSEL STABILITY REGULATIONS AND GUIDANCE TABLE 4-1 Active Inspected U.S.-Flag Vessels by Build Date Vessel Type Decade Built Fr ei gh t B ar ge Fr ei gh t Sh ip In du st ri al V es se l M ob ile O ff sh or e D ri lli ng U ni t O ff sh or e Su pp ly V es se l O il R ec ov er y Pa ss en ge r (I ns pe ct ed )
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EFFECTIVENESS OF CURRENT STABILITY REGULATIONS 45 NEEDED TECHNICAL STUDIES The committee was asked to identify the kinds of technical studies that are needed for the USCG to review the effectiveness of its stability standards. The committee believes the following studies could be helpful for this purpose.
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From page 46... ...
46 USCG VESSEL STABILITY REGULATIONS AND GUIDANCE identify not only those documents that require updating but also those that can be withdrawn or consolidated with other documents. Because this remains an area in which more technical work is needed, the committee suggests a methodology to assess the effectiveness of policy and other guidance documents later in this report (see Chapter 6)
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From page 47... ...
EFFECTIVENESS OF CURRENT STABILITY REGULATIONS 47 Because some of these vessels operate with a minimum stability margin, the accuracy of the initial lightship incline test can also influence whether the loaded vessel meets stability requirements. The USCG may want to follow up on 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.
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From page 48... ...
48 USCG VESSEL STABILITY REGULATIONS AND GUIDANCE roll motion can occur as the varying transverse stability provides impetus to the rolling action at both extremes of the motion. Roll angles as great as 35 to 40 degrees with simultaneous extreme pitching have been reported, in some cases causing heavy damage and loss of containers (France et al.
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From page 49... ...
EFFECTIVENESS OF CURRENT STABILITY REGULATIONS 49 present a stability risk for dry bulk shipping.8 Severe list and even capsizing casualties have occurred in large ocean-going bulk carriers when their cargoes with high latent moisture content are exposed to agitation in the form of ship's motion, wave impact, and engine vibration during a voyage resulting in compaction of the cargo, causing cargo liquefaction and cargo flow to one side in a roll in heavy seas. To mitigate this risk, the IMO has instituted the International Maritime Solid Bulk Cargoes code, which stipulates that shippers are responsible for the testing and sampling of the cargo moisture levels and ensuring that they are below levels at which liquefaction can occur.
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From page 50... ...
50 USCG VESSEL STABILITY REGULATIONS AND GUIDANCE the true risks to vessels from loss of stability in adverse dynamic operating conditions, and not just from loss of quasi-static stability. If these new international criteria are approved as amendments to SOLAS, they would be applied to U.S.
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