Review of U.S. Coast Guard Vessel Stability Regulations (2018) / Chapter Skim
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Pages 11-30
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From page 11... ...
11 report. See Section 5 for additional details on and potential options for addressing these data issues.
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12 Figure 1a A vessel with sufficient righting forces. Figure 1b A vessel with insufficient righting forces.
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13 shipyard of that period to perform the required initial stability calculations. Vessel stability results from the association of the downward force of the vessel's weight centered at the center of mass (G)
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14 have significantly different hull forms from previous designs and with the metacentric height's inability to measure the vessel's stability at larger angles of heel, stability issues became more problematic. During the mid-19th century, naval architecture developed a newer quasi-dynamic method for measuring vessel stability that used the relating of righting energy to the area under the righting arm curve.
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15 Each heel angle then is a static snapshot of the vessel's stability. When multiplied by the vessel's displacement, the area under the curve for each heel angle determined the energy required to heel the vessel to that given heel angle.
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16 curve, 20 and 40 degrees of heel. Although requiring more staff to perform the calculations, this approach allowed more viable stability criteria as minimum righting forces at high angles of heel were specified and applied to newer generations of vessel designs.
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17 Figure 5 Righting arm curve approximating severe wind and rolling on a vessel. SOURCE: USCG, presentation to the committee by Jaideep Sirkar, March 2018.
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18 vessels that travel the high seas. The London-based International Maritime Organization (IMO)
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19 waters. In the mid-20th century, the United States designated USCG as the agency with responsibility for regulating and inspecting ships and commercial vessels registered in and operating within areas under the jurisdiction of the United States.
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20 There are many stakeholders with an interest in stability regulations, since maintenance of stability is one of the key factors in ensuring vessel safety and avoidance of environmental damage. The stakeholders include the thousands of vessel owners and operators, the vessel personnel and passengers, the cargo owners and shippers, the communities along the shores who can be affected by vessel accidents, and the government agencies tasked with enforcing the regulations and carrying out search and rescue.
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21 international commerce, and accordingly must comply with international stability regulations for legal operation (such as SOLAS, International Convention on Load Lines, and High-Speed Craft Safety) , in addition to those regulations found in the CFR.
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22 Subchapters K and H passenger vessels and covers subdivision and weathertight and watertight (WT) integrity.
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23 measures are applied to achieve the desired outcome, while avoiding unexpected consequences) , and writing in a form that is easily understood by both users and regulators.
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24 Reliance on Simple Static Stability Criteria In some parts of Subchapter S, simple static GM-based stability criteria, such as in 170.170 Weather Criteria, 171.050 Passenger Heeling Criteria, 172 Subpart E Tank Barges Carrying Hazardous Liquids, and 173.095(b) Towline Pull Criteria, are used for checking vessel stability.
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25 1. There are multiple document types, each containing policy decisions.
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26 Because of these differences, the report describes Subchapter T regulations in more detail to show some of the differences. Subchapter T, Part 178 Intact Stability and Seaworthiness contains the intact stability standards, while Part 179 Subdivision, Damage Stability Watertight Integrity Requirements contains the damage stability standards if applicable to the particular vessel.
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27 they may provide a better passenger loading capability. All other vessels must use the listed portions of the intact and, if applicable, damage stability standards of Subchapter S
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28 Intact Stability by Subchapter S Regulations For those vessels not permitted or whose owner chooses not to use the simplified stability proof test, Subchapter T, in 178.310 and 178.325, prescribes the parts of the Subchapter S regulations that must be met. The parts of Subchapter S that must be met depends on the type of vessel, power or sail.
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29 179.210 (b) -- All vessels less than 65 ft in length that (1)
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30 question to get a maximum permitted watertight bulkhead spacing. This method does not require any of the extensive damage stability calculations needed for larger Subchapter K and H passenger vessels that require the use of computer-based software.
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