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Review of U.S. Coast Guard Vessel Stability Regulations (2018)

Chapter: APPENDIX G SPECIFIC OPTIONS FOR AN UPDATE OF SUBCHAPTER S BY INDICATED PART

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Suggested Citation:"APPENDIX G SPECIFIC OPTIONS FOR AN UPDATE OF SUBCHAPTER S BY INDICATED PART." National Academies of Sciences, Engineering, and Medicine. 2018. Review of U.S. Coast Guard Vessel Stability Regulations. Washington, DC: The National Academies Press. doi: 10.17226/25258.
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Suggested Citation:"APPENDIX G SPECIFIC OPTIONS FOR AN UPDATE OF SUBCHAPTER S BY INDICATED PART." National Academies of Sciences, Engineering, and Medicine. 2018. Review of U.S. Coast Guard Vessel Stability Regulations. Washington, DC: The National Academies Press. doi: 10.17226/25258.
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Suggested Citation:"APPENDIX G SPECIFIC OPTIONS FOR AN UPDATE OF SUBCHAPTER S BY INDICATED PART." National Academies of Sciences, Engineering, and Medicine. 2018. Review of U.S. Coast Guard Vessel Stability Regulations. Washington, DC: The National Academies Press. doi: 10.17226/25258.
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Suggested Citation:"APPENDIX G SPECIFIC OPTIONS FOR AN UPDATE OF SUBCHAPTER S BY INDICATED PART." National Academies of Sciences, Engineering, and Medicine. 2018. Review of U.S. Coast Guard Vessel Stability Regulations. Washington, DC: The National Academies Press. doi: 10.17226/25258.
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Suggested Citation:"APPENDIX G SPECIFIC OPTIONS FOR AN UPDATE OF SUBCHAPTER S BY INDICATED PART." National Academies of Sciences, Engineering, and Medicine. 2018. Review of U.S. Coast Guard Vessel Stability Regulations. Washington, DC: The National Academies Press. doi: 10.17226/25258.
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Suggested Citation:"APPENDIX G SPECIFIC OPTIONS FOR AN UPDATE OF SUBCHAPTER S BY INDICATED PART." National Academies of Sciences, Engineering, and Medicine. 2018. Review of U.S. Coast Guard Vessel Stability Regulations. Washington, DC: The National Academies Press. doi: 10.17226/25258.
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Suggested Citation:"APPENDIX G SPECIFIC OPTIONS FOR AN UPDATE OF SUBCHAPTER S BY INDICATED PART." National Academies of Sciences, Engineering, and Medicine. 2018. Review of U.S. Coast Guard Vessel Stability Regulations. Washington, DC: The National Academies Press. doi: 10.17226/25258.
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Suggested Citation:"APPENDIX G SPECIFIC OPTIONS FOR AN UPDATE OF SUBCHAPTER S BY INDICATED PART." National Academies of Sciences, Engineering, and Medicine. 2018. Review of U.S. Coast Guard Vessel Stability Regulations. Washington, DC: The National Academies Press. doi: 10.17226/25258.
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Suggested Citation:"APPENDIX G SPECIFIC OPTIONS FOR AN UPDATE OF SUBCHAPTER S BY INDICATED PART." National Academies of Sciences, Engineering, and Medicine. 2018. Review of U.S. Coast Guard Vessel Stability Regulations. Washington, DC: The National Academies Press. doi: 10.17226/25258.
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Suggested Citation:"APPENDIX G SPECIFIC OPTIONS FOR AN UPDATE OF SUBCHAPTER S BY INDICATED PART." National Academies of Sciences, Engineering, and Medicine. 2018. Review of U.S. Coast Guard Vessel Stability Regulations. Washington, DC: The National Academies Press. doi: 10.17226/25258.
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Suggested Citation:"APPENDIX G SPECIFIC OPTIONS FOR AN UPDATE OF SUBCHAPTER S BY INDICATED PART." National Academies of Sciences, Engineering, and Medicine. 2018. Review of U.S. Coast Guard Vessel Stability Regulations. Washington, DC: The National Academies Press. doi: 10.17226/25258.
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Suggested Citation:"APPENDIX G SPECIFIC OPTIONS FOR AN UPDATE OF SUBCHAPTER S BY INDICATED PART." National Academies of Sciences, Engineering, and Medicine. 2018. Review of U.S. Coast Guard Vessel Stability Regulations. Washington, DC: The National Academies Press. doi: 10.17226/25258.
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Suggested Citation:"APPENDIX G SPECIFIC OPTIONS FOR AN UPDATE OF SUBCHAPTER S BY INDICATED PART." National Academies of Sciences, Engineering, and Medicine. 2018. Review of U.S. Coast Guard Vessel Stability Regulations. Washington, DC: The National Academies Press. doi: 10.17226/25258.
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Suggested Citation:"APPENDIX G SPECIFIC OPTIONS FOR AN UPDATE OF SUBCHAPTER S BY INDICATED PART." National Academies of Sciences, Engineering, and Medicine. 2018. Review of U.S. Coast Guard Vessel Stability Regulations. Washington, DC: The National Academies Press. doi: 10.17226/25258.
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Suggested Citation:"APPENDIX G SPECIFIC OPTIONS FOR AN UPDATE OF SUBCHAPTER S BY INDICATED PART." National Academies of Sciences, Engineering, and Medicine. 2018. Review of U.S. Coast Guard Vessel Stability Regulations. Washington, DC: The National Academies Press. doi: 10.17226/25258.
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Suggested Citation:"APPENDIX G SPECIFIC OPTIONS FOR AN UPDATE OF SUBCHAPTER S BY INDICATED PART." National Academies of Sciences, Engineering, and Medicine. 2018. Review of U.S. Coast Guard Vessel Stability Regulations. Washington, DC: The National Academies Press. doi: 10.17226/25258.
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Suggested Citation:"APPENDIX G SPECIFIC OPTIONS FOR AN UPDATE OF SUBCHAPTER S BY INDICATED PART." National Academies of Sciences, Engineering, and Medicine. 2018. Review of U.S. Coast Guard Vessel Stability Regulations. Washington, DC: The National Academies Press. doi: 10.17226/25258.
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Suggested Citation:"APPENDIX G SPECIFIC OPTIONS FOR AN UPDATE OF SUBCHAPTER S BY INDICATED PART." National Academies of Sciences, Engineering, and Medicine. 2018. Review of U.S. Coast Guard Vessel Stability Regulations. Washington, DC: The National Academies Press. doi: 10.17226/25258.
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Suggested Citation:"APPENDIX G SPECIFIC OPTIONS FOR AN UPDATE OF SUBCHAPTER S BY INDICATED PART." National Academies of Sciences, Engineering, and Medicine. 2018. Review of U.S. Coast Guard Vessel Stability Regulations. Washington, DC: The National Academies Press. doi: 10.17226/25258.
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Suggested Citation:"APPENDIX G SPECIFIC OPTIONS FOR AN UPDATE OF SUBCHAPTER S BY INDICATED PART." National Academies of Sciences, Engineering, and Medicine. 2018. Review of U.S. Coast Guard Vessel Stability Regulations. Washington, DC: The National Academies Press. doi: 10.17226/25258.
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Suggested Citation:"APPENDIX G SPECIFIC OPTIONS FOR AN UPDATE OF SUBCHAPTER S BY INDICATED PART." National Academies of Sciences, Engineering, and Medicine. 2018. Review of U.S. Coast Guard Vessel Stability Regulations. Washington, DC: The National Academies Press. doi: 10.17226/25258.
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Suggested Citation:"APPENDIX G SPECIFIC OPTIONS FOR AN UPDATE OF SUBCHAPTER S BY INDICATED PART." National Academies of Sciences, Engineering, and Medicine. 2018. Review of U.S. Coast Guard Vessel Stability Regulations. Washington, DC: The National Academies Press. doi: 10.17226/25258.
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Suggested Citation:"APPENDIX G SPECIFIC OPTIONS FOR AN UPDATE OF SUBCHAPTER S BY INDICATED PART." National Academies of Sciences, Engineering, and Medicine. 2018. Review of U.S. Coast Guard Vessel Stability Regulations. Washington, DC: The National Academies Press. doi: 10.17226/25258.
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105 APPENDIX G SPECIFIC OPTIONS FOR AN UPDATE OF SUBCHAPTER S BY INDICATED PART Appendix G reviews each Part and Subpart of Subchapter S, discusses the current state of the regulation, and identifies updates or changes the U.S. Coast Guard (USCG) could pursue. Candidate changes are provided at the end of the discussion of each Subpart. PART 170—STABILITY REQUIREMENTS FOR ALL INSPECTED VESSELS Part 170, Subpart E—Intact Stability Criteria Subpart E is reasonably up-to-date. It was last updated during the 2010 passenger weight regulation project. The “specific applicability” section, § 170.160, points users in the correct direction. 170.165—Ocean-Going Ships with International Certificates Currently in 46 Code of Federal Regulations (CFR) 170.165, vessels with one of the listed international certificates, such as Safety of Life at Sea (SOLAS) Cargo Ship or Passenger Ship Safety Certificate, International Load Line, or High Speed Craft, must meet the Intact Stability (IS) Code. This covers most ocean-going vessels under the U.S. flag, since they have one or more of the cited certificates. This provision could be retained for the reasons given when discussing the IS Code (see Appendix C). 170.170 Weather Criteria This is the traditional USCG intact stability criteria developed originally from data for traditionally shaped ocean-going ships.26 The sample vessels were either larger than the small 26 Marine Safety Manual, Vol. 4, Chap. 6, 6.E.20.a, “In the early 1940’s the Coast Guard developed an intact GM criterion using Liberty Ship and T-2 tanker type vessels as the data base. This criterion has remained in effect and is

106 passenger ships or smaller than the large vessels in service today to which this criterion is sometimes applied. Furthermore, these criteria are initial metacentric height (GM) criteria that determine the GM for small angles of heel of the upright vessel and are “a poor indicator of overall stability, especially in response to large heeling forces and moments as might be experienced by a vessel in heavy weather where high winds and seas can be expected.”27 The criteria are also a poor indicator of overall stability for ships with low freeboard that quickly lose righting arm at small angles of heel. The weather criteria’s applicability to “each vessel” is too broad. As a general standard for certain domestic vessels, it can continue to be useful, particularly for vessels with large wind areas such as some small passenger vessels with large canopies. The “weather criteria” could be retained as an available standard, as they are currently referenced in numerous other subchapters (such as M, T, and K), as long as they are not the sole standard, except in special cases. Vessels for which they are the sole criteria could be reevaluated as to whether these would be the governing criteria if they were reevaluated for stability under the CFR with changes suggested by the committee. If not, vessels could update to include the additional criteria that will be applied to similar vessels under the updated CFR. A comparable international regulation is the IS Code, Part A, Chapter 2, Section 2.3, Severe wind and rolling criterion (weather criterion). Some confusion with 170.170 Weather Criteria will be inevitable as these two criteria have similar names. The IS Code criterion is intended to check vessel stability against capsizing in wind and waves in the case of loss of referred to as the weather criterion (now in 46 CFR 170.170). …Also, the vessels in the data base were much larger than T-boats and much smaller than car carriers.” 27 Marine Safety Center, Technical Report, SS EL FARO, Stability and Structures, March 22, 2017, p. 45.

107 propulsion power and the vessel drifting abeam to the seas, one of the extreme stability hazards a vessel could face. Whether the required stability from 170.170 or Section 2.3 will require a higher level of safety depends on the vessel shape (vessels with high wind profile will generally require a higher initial GM under 170.170). However, the IS Code Section 2.3 is inappropriate for most domestic vessels, which would involve retaining the 170.170 Weather Criteria for most domestic service, non-ocean-going vessels (vessels operating less than 20 mi from the coast). However, an exception could be made for vessels operating on the Great Lakes, where they can be far from land and face conditions similar to ocean service. A new regulation referencing this paragraph in the IS Code could be added for domestic vessels that are ocean-going or in equivalent Great Lakes service away from land. Candidate Changes 1. Retain 170.170 Weather Criteria as an available standard, but do not make it the sole criterion, except in special cases. It could be applied to vessels in domestic service that are non-ocean-going or that do not operate in Great Lakes service away from land. 2. For ocean-going vessels and larger Great Lakes vessels, the IS Code Section 2.3, Severe Wind and Rolling Criterion (Weather Criterion), could be applied as appropriate to the vessel’s route and service. 3. Because of the shortcomings of the 170.170 criteria for overall stability assessment, existing vessels for which it is the sole criterion would not be automatically grandfathered in during subsequent regulatory updates. The existing vessel stability documents could be updated to include the additional criteria that may apply to them to ensure an adequate level of stability safety is achieved.

108 170.173—Vessels with Unusual Proportion and Form This section is similar to the IS Code Part A, Section 2.2, Criteria regarding righting lever curve properties. The IS Code is applicable to vessels in ocean service, and so a similar requirement is applied to all U.S. vessels to which this Part applies and that also operate in exposed or ocean waters. Section 170.173 does contain reduced requirements in Part (e) for vessels in partially protected and protected routes, which appear appropriate for the broad range of vessel types and services covered by this regulation. The basis for this is discussed in more detail in the Marine Safety Manual.28 Paragraph (a) indicates this Part is applicable to mechanically powered vessels less than 328 ft (100 m) in length, other than tugboats or towboats. Since this Part duplicates the IS Code, which applies to longer vessels, the restriction on length could be removed. This Part could also apply to all self-propelled vessels and not just to vessels of unusual proportion and form. When appropriate, USCG does develop exceptions for special vessel types, such as tugboats, towboats, catamarans, high-speed craft, and boats under 24 m, etc. This would also require deleting Section 170.170(d), which appears to apply Section 170.173 only to vessels that do not meet the standard ship proportions. Candidate Changes 1. Remove the restriction on length (to vessels less than 328 ft [100 m]) as there is no reason for this restriction at this time and it does not apply in the IS Code, Part A, Section 2.2. 2. Apply this requirement to all self-propelled vessels, except for special types and small boats to which the IS Code, Part A, Section 2.2 also does not generally apply. 28 Marine Safety Manual, Vol. 4, Chap. 6, 6.E.20.k, Energy for Less than Ocean Service.

109 Part 170, Subparts A Through D and F Through I These subparts lay out the essential and general requirements similar to all the other Subchapters and they could be retained, but modified in some cases as proposed in the following paragraphs. It is important to review these subparts for currency. Part 170, Subpart F—Determination of Lightship Weight Displacement and Centers of Gravity This subpart duplicates much of what is in IS Code, Part B, Annex 1—Detailed Guidance for the Conduct of an Inclining Test. This subpart appears to be a legacy requirement retained in the CFR as there is nothing special or different about lightship weight determination for U.S. vessels that would require different text than for international vessels. On that basis, Subpart F could be replaced with the IS Code guidance to make the conduct of lightship determination more universal with other nations and to incorporate the latest guidance. Special requirements applicable to U.S. vessels (especially smaller vessels) and circumstances could be added as needed in the framework of the IS Code guidelines. In certain cases, the CFR could continue to allow a local surveyor to change requirements to suit local conditions or could allow smaller vessels that do not meet the IS Code to invoke ASTM F1321.29 Part 170.200—Estimated Lightweight Vertical Center of Gravity This section permits certain tank vessels, either ships or barges, to use an estimated vertical center of gravity (VCG), rather than requiring an incline test to determine the actual VCG. For ships, the estimated value is 70% of depth and for barges, 60% of depth. Comments received by the committee30 indicated that industry finds it onerous to require new deadweight survey and 29 Standard Guide for Conducting a Stability Test (Lightweight Survey and Inclining Experiment) to Determine the Light Ship Displacement and Centers of Gravity of a Vessel. (https://www.astm.org/Standards/F1321.htm) 30 Personal communication from Joshua Sebastian, The Shearer Group, providing comments on stability, April 16, 2018.

110 stability calculations for relatively small changes to lightship weight to barges that are in slight excess of the 2% limit, but that do not change the full load displacement of the barge. Since the barge VCG was originally estimated at 60% of the depth, and there is no change in the depth, there is no reason it cannot continue to be 60% of the depth since the changes are small and would not change the justification for using the estimated VCG basis. Essentially nothing is changed in the full load stability of the barge and the critical value for stability, but a lot of effort has been exerted to update documentation and the owner has to wait for stability reapproval before using the barge again, a loss of revenue. For vessels that use estimated VCG, USCG could consider vessel modifications that do not change the barge shape or profile significantly and do not change the full load displacement. That greater margin could be allowed for changes in lightweight before new deadweight measurement and new stability documents are required. USCG could request industry to study this further and propose an allowable change in lightship weight based on demonstrated minimal effect on overall barge stability in the critical full load cases. Another area of concern for industry31 is the current USCG requirement that during an incline test at least one pendulum shall be used. A total of three incline measurement instruments are required and alternative methods can be used for two of these, such as U tubes or inclinometers. IMO IS Code in Annex 1, Section 2.4.7, has a similar requirement that at least one of the inclination instruments be a pendulum. For some vessels, such as deck barges and some smaller vessels, installation of a pendulum in a place not affected by wind (inside the hull) is impractical and, furthermore, digital inclinometers currently have a high degree of accuracy, 31 Personal communication from Joshua Sebastian, The Shearer Group, providing comments on stability, April 16, 2018.

111 higher than the pendulum measurement, so the requirement for at least one pendulum may be archaic. Consideration could be made to revise the USCG guidance so that where a pendulum is impractical, use of inclinometers only could be allowed. Candidate Changes 1. USCG could consider replacing Subpart F with the IS Code guidance to make the conduct of lightship determination more universal with other nations and to incorporate the latest guidance. Special requirements applicable to U.S. vessels and circumstances can be added as needed in the framework of the IS Code guidelines. 2. Tank vessels that use estimated VCG and undergo vessel modifications that do not change the barge shape or profile significantly and do not change the full load displacement could be allowed to have a greater margin for changes in lightweight than the traditional 2% of weight and 1% of Length (L) for Longitudinal Center of Gravity (LCG) before new deadweight measurement and new stability documents are required. USCG could request industry study this further and propose a change in the allowable change in lightship weight based on demonstrated minimal effect on overall barge stability in the critical full load cases. 3. USCG guidance could be revised so that where use of a pendulum is impractical, use of inclinometers only is allowed considering the accuracy and repeatability obtainable with modern electronic inclinometers for vessels that are not stability limited, such as barges. Part 170, Subpart H—Watertight Bulkhead Doors This subpart contains detailed requirements for watertight doors, some of which are archaic, e.g., requirements for coalbunker doors that can be deleted. It also refers only to an ASTM standard

112 for watertight doors, and with many doors acquired on a worldwide basis, this requirement unduly hinders the purchase of watertight doors. This subpart could be updated and aligned with SOLAS where practical, as SOLAS contains many detailed requirements for watertight doors (Chapter II-1, Part B-2, Subdivision, Watertight and Weathertight Integrity). Reference could also be made to doors meeting comparable international standards to ASTM, such as Class requirements. These updates could enhance the ability to build or purchase internationally designed vessels in the United States and to sell U.S.-designed vessels overseas. In addition, this section contains no requirements about keeping watertight doors closed, which could be added to duplicate SOLAS requirements. Candidate Changes 1. This subpart could be updated and aligned with the more modern SOLAS requirements. 2. Allowed standards for watertight doors could be expanded beyond the cited ASTM standard to allow the use of Class-approved, internationally produced doors, as the current ASTM standard is very restrictive, particularly to U.S. Flag vessels in international trade. 3. Update to include a requirement to keep watertight doors closed. SOLAS provides good guidance on this. Part 170. Subpart I—Free Surface Section 170.295 contains the requirements for free surface corrections for passive roll stabilization tanks. These tanks are designed to counter the effect of vessel rolling by having the water slosh back and forth out of sync with the vessel roll, so they provide a force to counteract the wave roll force. The free surface effect of the tanks is reduced by the shape of the tanks and

113 the amount of liquid in them. Section 170.295(b) provides a formula with a factor K, which is the reduction factor for the full free surface rise in VCG. The CFR provides a graphical method to calculate K, which is outdated considering most of these calculations will be done by computer. The explanatory text provided under this Part is quite difficult to follow. Candidate Change 1. Replace the graphical-based method for determining the roll stabilization tank free surface reduction factor with a method that uses the capabilities of computers and is easier to understand. PART 171—SPECIAL RULES PERTAINING TO VESSELS CARRYING PASSENGERS This Part provides intact and damage stability regulations for passenger ships and applies to ships inspected under Subchapters H and K (large and medium-sized passenger ships). The similar international regulations are IS Code for intact stability and SOLAS, Part B, Damage Stability, which is applicable to passenger ships of 24 m in length and greater carrying more than 12 passengers on international voyages. In general, U.S. Flag ships with SOLAS Passenger Ship Safety certificates are required to comply with the IS Code for intact stability (see Section 170.165) and SOLAS, Part B for damage stability (see Sections 171.001(d) and 171.080) in lieu of the requirements contained in this Part. The committee understands this policy. However, there are very few U.S. Flag passenger ships with SOLAS certification. Of interest is to what extent IMO regulations for intact and damage stability could be applied to smaller coastal passenger ships, which are generally the type of vessels to which this part of the CFR is applied. 171 Subpart A—General This subpart refers to harmonized SOLAS 2009, which has an in-force date of January 1, 2009; to update this subpart, USCG would need to reference (IBR or incorporation by reference) the

114 new resolution MSC.421(98), which also harmonized passenger and cargo ships damage stability, referred to as SOLAS 2020. The diagrams for stepped bulkheads are greatly out of date (and they look old), but they are still needed for margin line and floodable length discussions in other subparts. 171 Subpart B—Intact Stability Subpart B contains regulations for passenger ship intact stability. Section 171.050 contains regulations for mechanically propelled or non-self-propelled vessels. It contains a traditional formula for GM that is familiar to U.S. Flag operators and designers. In Subsection (c), it also allows alternate compliance for passenger ships by meeting the IS Code. Allowing designers to meet either the traditional CFR requirements or the equivalent international requirement provides the type of flexibility that could be adopted in other parts of Subchapter S, so there is no further comment on intact stability requirements for passenger ships. It is further noted that for specialized vessels to which the IS Code would not apply (pontoon vessels and sailing vessels), this Part of the CFR has specialized intact stability requirements, which appear appropriate. 171 Subpart C—Subdivision and Damage Stability Subpart C is based on the traditional deterministic damage stability requirements that have been in effect for many years. Although well known to U.S. operators and naval architects, these requirements are complex in application and are not used elsewhere in the world for ocean-going vessels. Passenger vessels on international voyages with SOLAS certificates that carry more than 12 passengers and were built after January 1, 2009, are exempt from the requirements of this Part if they comply with SOLAS, Chapter II-1, Part B (see Section 171.001(d)). Similarly, older passenger ships carrying more than 12 passengers that have a SOLAS Passenger Ship Safety Certificate are exempt from meeting the damage survival requirements in this Part if they meet

115 SOLAS, Chapter II-1, Part B, specifically the 2006 amendments (MSC 216(82)) per Section 171.080(g). Regarding Parts 171.060 to 171.068, applicable to Type 1 vessels, these parts apply the out-of-date SOLAS 1974—factor of subdivision requirements—and do not appear to be needed, as they are not applied to any current vessels (vessels to which Type 1 criteria apply all have to meet SOLAS requirements). Therefore, vessels to which SOLAS most directly applies could be allowed to comply solely with the international regulation. Whether to apply SOLAS-type damage stability requirements to vessels for which SOLAS is not directly applicable (Type II vessels) is discussed in the following paragraphs. Major differences exist between the SOLAS subdivision and damage stability requirements and the CFR subdivision and damage stability requirements in terms of the methods used to assess damage stability. The CFR uses a deterministic approach, which means discrete damages are assumed and the vessel has to survive these damages per specified survival criteria. As part of these requirements, for subdivision, there are requirements for the distance between transverse bulkheads and the locations of bulkheads based on vessel length and type, as well as the shape of bulkheads. For damage survival, damage dimensions and locations, such as between main watertight bulkheads, and the number of compartments to be assumed damaged at one time (one or two compartments) are all specified. The vessel is also required to survive the specified damages, including meeting certain requirements for height of the maximum water line after damage (below the margin line), angle of heel, lack of submersion of down flooding points, and reserve stability after damage. Although the application of this type of criteria is tedious if done by hand, properly programmed computerized hull stability programs can complete it

116 quickly. There is also a good safety record with the current requirements as few, if any, casualties are known to have resulted from damage stability loss for vessels that meet them. SOLAS applies a probabilistic damage stability standard. In this method a wide range of damage extents are assumed over one, two, or even three compartments; watertight bulkheads can be damaged; and a probability of occurrence is applied to each damage case. The survivability of the vessel for each damage case is then assessed, and an attained index, A, is determined, which is the sum of the product of the probability of occurrence and the probability of survival of each damage case. This is compared to a required index, R, the value of which for passenger ships is based on the vessel length, the number of passengers and crew, and lifeboat capacity. The key test is if A is greater than R: then, in general, the vessel passes the damage stability requirement, although it must also meet some other requirements. The advantage of the probability analysis is that it does not depend on somewhat unrealistic assumptions on extent of damage and the somewhat artificial assumption that key transverse bulkheads will not be damaged. However, the development of the probabilities of each type of damage is from casualty statistics data that are somewhat biased to conventional ships, which are most common and most involved in casualties.32 The development of the probabilities was not derived from casualty statistics of smaller passenger vessels, the type to which this Part is most commonly applied. Furthermore, the application of a probability-type analysis requires specialized software and is quite complex to those unfamiliar with the process, so many naval architects in the United States involved with the design of smaller passenger ships would likely find its application to be difficult, at least initially. 32 IMO Resolution MSC.281(85), Explanatory Notes to the SOLAS Chapter II-1 Subdivision and Damage Stability Regulations, Dec. 2008. See Part A, Introduction.

117 Candidate Changes 1. Because of the reasons cited above (database for smaller passenger vessels is unavailable, the difficulty of applying the probability-based damage stability process software, and the current experience of U.S. naval architects is with the existing Part 171 deterministic requirements), USCG may not want to expand the SOLAS-type probabilistic damage stability analysis requirements beyond those currently required to meet them, which is those with a SOLAS Passenger Ship Safety Certificate (i.e., Type 1 vessels). USCG could look for ways to improve and update the requirements in this Part, as many are quite old. As part of that process, the subdivision and damage stability requirements of other nations for domestic passenger vessels are a good reference. 2. The Type I damage stability requirement is the old SOLAS 1974—factor of subdivision—and is no longer needed as it is not applied to any current vessels. Vessels to which Type 1 criteria apply all have to meet SOLAS requirements, and it seems appropriate to delete Type I requirements from the CFR. Type II damage stability is used every day for Subchapter K and T boats. However, there are requirements for stepped and recessed bulkheads in the actual text of the Type I damaged stability requirements that might be needed for Type II requirements. Thus, this text could be added to the regulations pertaining to Type II damage stability. 171 Subparts D Through H These regulations provide useful guidance that pertain to Subchapters K and T boats and even certain Subchapter H vessels. PART 172—SPECIAL RULES PERTAINING TO BULK CARGOES

118 Part 172, Subpart B—Grain These regulations authorize the National Cargo Bureau to issue a “Document of Authorization” for grain-carrying vessels in international trade, and could be retained. The regulations further authorize the National Cargo Bureau to issue a “certificate of loading” for voyages on the Great Lakes. For specific ports on the East and West Coasts, the regulations prescribe the conditions and standard the master is to comply with, e.g., no delegation of this authority to the National Cargo Bureau. As described in Appendix D, Section 172.030 could have the text clarified and formulas corrected. Part 172, Subparts C and D—Barges and Vessels with Polluting Cargoes Subpart C applies to tank barges, rather than self-propelled ships or boats, and has its own requirements that differ from Subpart D, which applies to vessels. These regulations could be retained as the U.S. barge fleet numbers in the thousands and they are used in domestic service on rivers and inland waterways. Articulated Tug Barge (ATB) units are being employed more and more in oil service in place of towed barges, but the barges and combined units must meet Subchapter D requirements, similar to tank vessels. Where appropriate, USCG could consider reviewing the ATB requirements for possible update using the International Convention for the Prevention of Pollution by Ship (MARPOL) requirements as a starting point. The regulations contained in Subpart D are applicable to self-propelled vessels. The requirements are similar to those contained in MARPOL and appear appropriate For larger vessels, the application of MARPOL is directly applied. See Part 172.070, Intact Stability, which requires that tank vessels of 5,000 dwt and above comply with the intact stability requirements of IMO Resolution MEPC 117(52). This is an outdated reference to the MARPOL amendments of 2004 and is in effect a reference to MARPOL. This citation could be

119 updated to refer to the current requirements contained in MARPOL Annex I, Chapter 4, Part A, Regulation 27, Intact Stability. It is noted that the subpart is aligned with the IS Code, in that both apply the 5,000 dwt minimum of MARPOL Regulation 27 to oil tankers. It is further noted that the damage stability regulations in this Subpart are almost identical to those in MARPOL, Regulation 28, Subdivision and Damage Stability. By listing the requirements, rather than referencing MARPOL, it allows USCG to apply the same requirements to smaller vessels and domestic vessels, which MARPOL would not directly apply (MARPOL does not apply to domestic-only vessels), noting that MARPOL requirements are suitable for all tankers. USCG could state directly in this subpart that vessels have the option to comply with the intact and damage stability requirements of MARPOL Regulations 27 and 28, as applicable to the age, type, and size of the intended vessel, as an alternative method of complying with the requirements of this subpart. In this way, vessels can achieve compliance by meeting the latest, up-to-date version of MARPOL and do not have to wait for USCG to update this subpart as MARPOL is updated. This will facilitate the use of international designs in the United States and the transfer of vessels into and out of U.S. registry. Candidate Changes 1. Retain separate requirements for barges in Subpart C, but consider updating them. 2. Allow vessels to which Subpart D applies to comply with the requirements of MARPOL as an alternative, so that the latest version of MARPOL could be used rather than waiting for the slow rulemaking process to update the CFR to follow the changes in MARPOL. Part 172, Subparts E and F—Barges and Vessels with Hazardous Cargoes

120 As with Subpart C for Barges and Subpart D for vessels, Subpart E applies to Barges with Hazardous Cargoes and Subpart F to Vessels. There is a good reason for barges to have separate Subpart E requirements as the U.S. barge fleet in domestic service (rivers) is diverse and extensive. Consideration could be made to updating these as needed. The regulations in Subpart F duplicate much of what is contained in the International Bulk Chemical (IBC) Code, Chapter 2, Sections 2.5 to 2.9. Many of the requirements are identical as part of the USCG effort to align its requirements with applicable international codes. Candidate Change 1. For Subpart F, the option to comply directly with the IBC Code could be expressly stated in the CFR as an alternative to complying with the requirements of this subpart. Part 172, Subpart G—Liquid Gas Carriers This is another specialized vessel type where USCG has harmonized its stability regulations with the applicable international code, the International Ships Carrying Liquefied Gases in Bulk (IGC) Code, Chapter 2, by applying many of the same requirements. The CFR could expressly permit compliance with the requirements of IGC, Chapter 2, as an alternative to complying with this Part. Besides facilitating vessel design, which for gas carriers frequently means international designs, the IGC Code has a lot of useful guidance in Chapter 2, Section 2.4.2, on how to determine the extent of damage when dealing with the multiple types of independent tanks used on gas carriers. This guidance could be available to U.S. Flag vessels if compliance to IGC stability requirements were encouraged. Candidate Change 1. For Subpart G, the option to comply directly with the IGC Code could be expressly stated in the CFR as an alternative to complying with the requirements of this subpart.

121 PART 173—SPECIAL RULES PERTAINING TO VESSEL USE Part 173, Subpart B—Lifting USCG and industry advisors participated in the development of the recently approved IS Code, Part B, Section 2.9 requirements for “Ships engaged in lifting operations,”33 and due consideration by the IMO Subcommittee on Ship Design and Construction (SDC) was given to the current U.S. CFR regulations in Subpart B. For those vessels in domestic service, the current regulations could be maintained. U.S. vessels operating under SOLAS could comply with the new IS Code. Candidate Change 1. A review of the current Subpart B compared to the IS Code, Part B, Section 2.9, Ships engaged in lifting operations, could be conducted. As is the case with all references to the IMO requirements, whether a Convention or a recommendation in a circular, text in the CFR would need to delineate the “shoulds” and the “shalls” and define any “left to the Administration” text. Part 173, Subpart C—School Ships These regulations could be retained, but consideration given to incorporating the provisions of the IMO Special Purpose Ship (SPS) Code.34 The requirements for numbers of “persons” on board could use the “reduced” numbers based on Paragraph 2.2 from the SPS Code for public nautical school ships, § 173.051. The number of persons allowed on civilian nautical school and sailing school vessels, § 173.052 and § 173.053, respectively, could be retained. The ‘R’ 33 IS Code, Part B amendments: Resolution MSC.415(97), adopted Nov.25, 2016. 34 SPS Code: Resolution MSC.266(84), Code on Safety for Special Purpose Ships, 2008.

122 (required subdivision index) for SPS Code vessels currently remains as SOLAS 2009, not the new harmonized SOLAS 2020.35 Candidate Change 1. Incorporate the provisions of the IMO-issued SPS Code as applicable, since the code directly applies to nautical training ships. Part 173, Subpart D—Oceanographic Research These requirements could be retained. Many U.S. Flag vessels are in international service, but there are some oceanographic vessels that only have a Certificate of Inspections (COI), thus many of the requirements in this subpart would need to be retained for these vessels. However, many of the designers of domestic research vessels also design larger vessels that are in international operations. The designers are familiar with the SPS Code and SOLAS; USCG could reference the SPS Code as an IBR and revise the domestic requirements based on international requirements. Candidate Change 1. Update Subpart D to be more in line with SPS Code requirements and allow compliance with the SPS Code as an alternative method of compliance. Part 173, Subpart E—Towing As with Part 173, Subpart B, noted previously, USCG and industry advisors participated in the development of the new IS Code, Part B, Section 2.8 requirements for ships engaged in towing and escort operations. Although the current regulations in Subpart E are out of date, there is a 35 Amended: Resolution MSC.408(96), Chapter 2—a revised Paragraph 2.2 to retain the Required Index, R, from SOLAS 2009.

123 large domestic towing industry, and for these vessels the simple requirements in Subpart E might be sufficient. Candidate Changes 1. For new escort tugs with Z-drives and V-S propulsors, the current Subpart E is inadequate. Many of these U.S. vessels are designed to be SOLAS-compliant vessels and they would need to comply with the new IS Code, Part B, Section 2.8. Revision of Subpart E in this case will be extensive due to the need to reference Section 2.8 requirements fully and inclusion of the IBR. 2. For conventional, domestic service tugboats and towboats, retain Subpart E, but update requirements for new vessels in consideration of the IS Code. PART 174—SPECIAL RULES PERTAINING TO SPECIFIC VESSEL TYPES Part 174, Subpart B—Deck Cargo Barges Deck cargo barges have been a traditional method of transport in the United States. The regulations in Subpart B apply to (1) oceans, (2) the Great Lakes, and (3) rivers, bays, and sounds, with different minimum required areas under the GZ curve for each service. In contrast, the “pontoons” in the IS Code, Part B, Section 2.2, apply to seagoing pontoons, the IMO term for barges. Subpart B would require revision for consistency of terminology. USCG and industry advisors participated in the development of Section 2.2 when the Intact Stability Guidelines (the previous document was an Assembly resolution) were codified into the present IS Code.36 Candidate Change 36 Previous Intact Code: Resolution A.749(18), Code on Intact Stability for All Types of Ships Covered by IMO Instruments, and amended by Resolution MSC.75(69).

124 1. Update Subpart B for consistency of terminology and include consideration of the requirements in IS Code, Part B, Section 2.2. Part 174, Subpart C—MODU Stability USCG and industry advisors participated in the development of the Mobile Offshore Drilling Unit (MODU) Code at IMO; damage stability in the MODU Code37 is based largely on the early American Bureau of Shipping Rules for MODUs. The code is recommendatory; thus, some sort of regulation would be needed in Subchapter S to enforce the standards, even for MODUs engaged internationally. Although the code is not mandatory, MSC adopts amendments on a regular basis. Candidate Change 1. As noted with other parts of the CFR that essentially overlap an international code, compliance with the MODU Code stability requirements could be an available option to operators and designers to comply with this Part, as many have to potentially meet both requirements and this would facilitate the use of international designs. It would also allow designers the option of meeting the latest requirements as the international code is updated, without having to wait for the CFR update process. The MODU Code in Sections 3.1 to 3.8 contains more details on specific operational requirements applicable to MODU stability that could enhance safety if MODUs were encouraged by the CFR to comply with the MODU Code. Part 174, Subpart E—Tugboats and Towboats 37 MODU Code: Code for the Construction and Equipment of Mobile Offshore Drilling Units, 2009, A.1023(26). Recently amended: Resolution MSC.359(92) in 2015.

125 This Subpart—intact stability requirements—could be considered for combination with the requirements of Part 173, Subpart E. However, because Part 174 pertains to vessel type, while Part 173 is for vessel use, this subpart would need to be retained as a separate subpart because of the special characteristics of tugboats and towboats (vessel shape and low freeboard). Due consideration could be given to the mandatory requirements in Part A of the IS Code. Candidate Change 1. Retain this as a separate subpart and review the requirements against those in the IS Code, Part A, and update where appropriate. Part 174, Subpart G—Offshore Supply Vessel Stability Offshore Supply Vessels (OSVs) are a special U.S. “breed” of vessel that has been adopted worldwide. OSVs, as regulated by Subchapter L, permit the operator to carry offshore workers and even limited quantities of fuel and chemicals used by the oil exploration and production industry. Domestic OSVs can carry up to 36 offshore workers. If the OSV is in international service and carrying more than 12 workers or passengers, it must be certified as a passenger vessel. A significant portion of the U.S. OSV fleet is under 100 m and operated entirely in domestic (primarily Gulf of Mexico [GoM] service). For this reason, much of Subpart G is necessary, although it could be reviewed for currency. IMO requirements–both recommendatory–are in Part B of the IS Code, Section 2.4 (Offshore supply vessels), and Resolution MSC.235(82), Guidelines for the design and construction of offshore supply vessels, 2006. As with all IMO regulations and guidelines, USCG and industry advisors participated in their development. The USCG regulations were considered in each instrument’s development at

126 the sessions of the Subcommittee on Stability and Load Lines and on Fishing Vessels Safety (SLF).38 Candidate Change 1. Subpart G could be retained. It could be reviewed to ensure that the domestic requirements are updated based on the latest IMO regulations. Also update the references (IBR) to the OSV Guidelines and the IS Code, both Part A and the alternate intact requirements in Part B, Section 2.4.5. Part 174, Subpart J—Dry Cargo Ships This subpart specifies that all new cargo ships of 500 gross tons and above, with a contract date of February 1, 1992, or later, or in compliance with other definitions of a new vessel, must comply with the minimum standard of subdivision and damage stability applicable to that ship under IMO Resolution MSC.216(82). Per Section 174.007, this resolution adopted 2006 Amendments to SOLAS. This is the type of direct reference to an IMO requirement as an acceptable standard for compliance is a model that could be used for other parts as described in the preceding paragraphs. What would be needed in this subpart are slight amendments to incorporate (and IBR) the new harmonized damage stability requirements in Resolution MSC.421(98) (SOLAS 2020). Some other minor textual revisions are also needed. It is important to retain the in-force dates for the USCG regulations to conform to the dates for dry cargo ships in Resolution MSC.19(58). These 1990 amendments contained a new Part B-1 for cargo ship damage stability—Regulations 25-1 through 25-10—for ships constructed on or after February 1, 1992. 38 OSV Code: Resolution MSC.235(82), Guidelines for the design and construction of offshore supply vessels, 2006.

127 Candidate Change 1. As SOLAS is updated in the future, the applicability referenced in this subpart could be updated as well to separate vessels built in compliance with a previous version of SOLAS from the current version of SOLAS, following the applicability dates in SOLAS. Currently this subpart does not do that properly as it applies SOLAS 2006 Amendments (IMO Resolution MSC.216(82)) with new vessel applicability dates for previous SOLAS Amendments from the 1990s. POLAR CODE The international Polar Code39 entered into force on January 1, 2017. The additional stability requirements are contained in Chapters 4 (Subdivision and Stability) and 5 (Watertight and Weathertight integrity). It is similar to the IS Code, in that there are mandatory and recommendatory parts. Part I-A contains safety measures and is mandatory, while Part I-B is guidance or recommendatory. Candidate Change 1. A reference to the Polar Code for the stability of U.S. vessels operating where the Polar Code would apply could be added to the CFR. 39 Polar Code: Resolution MSC.385(94), International Code for Ships Operating in Polar Waters, adopted Nov. 2014.

Next: APPENDIX H WEIGHT GROWTH IN PASSENGER VESSELS »
Review of U.S. Coast Guard Vessel Stability Regulations Get This Book
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On September 12, 2018, TRB released a letter report that reviews regulations and policy documents that establish vessel stability requirements for U.S. Flag vessels. The review, conducted at the request of the U.S. Coast Guard Office of Design and Engineering Standards, considers options to make and keep stability requirements current, align them better with international standards, and improve their consistency, clarity, and usability. In addition to identifying a series of promising options for these purposes, the report makes recommendations to the Coast Guard on coordinating with industry advisory groups and collecting, managing, and analyzing data to inform regulatory decisions.

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