National Academies Press: OpenBook

Review and Update of U.S. Coast Guard Vessel Stability Regulations and Guidance (2019)

Chapter: Appendix C: Results of Lightship Weight Sensitivity Analysis for Selected Freight Vessels

« Previous: Appendix B: U.S.-Inspected Fleet Vessel Data
Page 95
Suggested Citation:"Appendix C: Results of Lightship Weight Sensitivity Analysis for Selected Freight Vessels." 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 95
Page 96
Suggested Citation:"Appendix C: Results of Lightship Weight Sensitivity Analysis for Selected Freight Vessels." 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 96
Page 97
Suggested Citation:"Appendix C: Results of Lightship Weight Sensitivity Analysis for Selected Freight Vessels." 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 97
Page 98
Suggested Citation:"Appendix C: Results of Lightship Weight Sensitivity Analysis for Selected Freight Vessels." 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 98
Page 99
Suggested Citation:"Appendix C: Results of Lightship Weight Sensitivity Analysis for Selected Freight Vessels." 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 99

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PREPUBLICATION COPY—Uncorrected Proofs 95 Appendix C Results of Lightship Weight Sensitivity Analysis for Selected Freight Vessels TABLE C-1 Car Carrier Approximate Vessel Particulars Vessel Type Car Carrier LBP (m) 170 Beam (m) 32 Depth (m) 28 Draft (m) 8.5 Lightship (mt) 12,500 VCG (m-ABL) 16.0 Full Load Displacement (mt) 25,000 GM (m) 1.4 Least GM Condition Full Load Arrival Displacement (mt) 23,500 VCG (m-ABL) 14.0 GM (m) 0.4 Worst Loading Condition Full Load Condition (D) - Trimmed Weight Increase Pct Weight Increase mt VCG m Lightship mt Loading Case VCG (m) Loading Case KM (m) GM Margin (m) GM Required (m) 0 0 15.500 12,500 13.900 14.330 0.280 0.150 2% 250 28.000 12,750 14.050 14.350 0.150 0.150 4% 500 28.000 13,000 14.190 14.380 0.040 0.150 6% 750 28.000 13,250 14.340 14.420 –0.070 0.150 2% 250 15.500 12,750 13.920 14.350 0.280 0.150 4% 500 15.500 13,000 13.930 14.380 0.300 0.150 6% 750 15.500 13,250 13.950 14.420 0.320 0.150 NOTE: GM = metacentric height; KM = height of metacenter above the keel; LBP = length between perpendiculars; m = meter; m-ABL = meters above baseline; mt = metric ton; pct = percentage; VCG = vertical center of gravity.

PREPUBLICATION COPY—Uncorrected Proofs 96 TABLE C-2 Large Trailership Approximate Vessel Particulars Vessel Type Ro-Ro Trailer and Car Carrier LBP (m) 240 Beam (m) 36 Depth (m) 28 Draft (m) 9.8 Lightship (mt) 28,100 VCG (m-ABL) 16.0 Full Load Displacement (mt) 52,100 GM (m) 2.1 Least GM Condition Arrival with 50% Cargo Displacement (mt) 45,600 VCG (m-ABL) 15.0 GM (m) 0.3 Worst Loading Condition: Arrival with 50% Cargo Weight Increase Pct Weight Increase mt VCG m Lightship mt Loading Case VCG (m) Loading Case KM (m) GM Margin (m) GM Required (m) 0% 0 15.82 28,127 15.41 17.73 0.30 2.03 2% 563 28.35 28,690 15.57 17.71 0.19 1.96 4% 1,125 28.35 29,253 15.72 17.68 0.08 1.89 6% 1,688 28.35 29,815 15.87 17.65 –0.03 1.82 2% 563 15.82 28,690 15.41 17.71 0.34 1.96 4% 1,125 15.82 29,253 15.42 17.68 0.38 1.89 6% 1,688 15.82 29,815 15.42 17.65 0.41 1.82 NOTE: GM = metacentric height; KM = height of metacenter above the keel; LBP = length between perpendiculars; m = meter; m-ABL = meters above baseline; mt = metric ton; pct = percentage; VCG = vertical center of gravity.

PREPUBLICATION COPY—Uncorrected Proofs 97 TABLE C-3 Naval Auxiliary/UNREP Vessel Designed to Commercial Standards Approximate Vessel Particulars Vessel Type Cargo LBP (m) 199.550 Beam (m) 32.200 Depth (m) 18.700 Draft (m) 9.780 Lightship (mt) 25,079 VCG (m-ABL) 14.198 Full Load Displacement (mt) 44,777 GM (m) 2.750 Least GM Condition Full Load Condition (D) - Trimmed Displacement (mt) 41,571 VCG (m-ABL) 12.297 GM (m) 0.637 Worst Loading Condition Full Load Condition (D) - Trimmed Weight Increase Pct Weight Increase mt VCG m Lightship mt Loading Case VCG (m) Loading Case KM (m) GM Margin (m) GM Required (m) 0 0 14.198 25,079 12.297 15.558 0.245 2.624 2% 502 18.700 25,581 12.374 15.525 0.058 2.705 4% 1,003 18.700 26,082 12.448 15.494 –0.129 2.790 6% 1,505 18.700 26,584 12.521 15.463 –0.358 2.920 2% 502 14.198 25,581 12.320 15.525 0.111 2.705 4% 1,003 14.198 26,082 12.342 15.494 –0.023 2.790 6% 1,505 14.198 26,584 12.364 15.463 –0.201 2.920 NOTE: GM = metacentric height; KM = height of metacenter above the keel; LBP = length between perpendiculars; m = meter; m-ABL = meters above baseline; mt = metric ton; pct = percentage; VCG = vertical center of gravity.

PREPUBLICATION COPY—Uncorrected Proofs 98 TABLE C-4 Product Tanker (approximate 330kbbl) Approximate Vessel Particulars Vessel Type Product Tanker LBP (m) 180 Beam (m) 32 Depth (m) 19 Draft (m) 13.3 Lightship (mt) 11,400 VCG (m-ABL) 12.0 Full Load Displacement (mt) 60,500 GM (m) 1.3 Least GM Condition Homogeneous Cargo Departure (S.G.=0.6821) Displacement (mt) 48,700 VCG (m-ABL) 12.0 GM (m) 2.2 Worst Loading Condition Homogeneous Cargo Departure (S.G.=0.6821) Weight Increase Pct Weight Increase mt VCG m Lightship mt Loading Case VCG (m) Loading Case KM (m) GM Margin (m) GM Required (m) 0% 0 12.392 11,359 11.685 13.992 1.413 0.150 2% 227 19.100 11,587 11.720 13.983 1.369 0.150 4% 454 19.100 11,814 11.754 13.973 1.325 0.150 6% 682 19.100 12,041 11.788 13.963 1.281 0.150 2% 227 12.392 11,587 11.688 13.393 1.400 0.150 4% 454 12.392 11,814 11.692 13.973 1.387 0.150 6% 682 12.392 12,041 11.695 13.963 1.374 0.150 NOTE: GM = metacentric height; KM = height of metacenter above the keel; LBP = length between perpendiculars; m = meter; m-ABL = meters above baseline; mt = metric ton; pct = percentage; VCG = vertical center of gravity.

PREPUBLICATION COPY—Uncorrected Proofs 99 TABLE C-5 3000 TEU Containership Approximate Vessel Particulars Vessel Type Containership LBP (m) 220 Beam (m) 32 Depth (m) 18 Draft (m) 10.5 Lightship (mt) 15,400 VCG (m-ABL) 14.0 Full Load Displacement (mt) 48,500 GM (m) 1.3 Least GM Condition Full Load Departure Displacement (mt) 47,800 VCG (m-ABL) 14.0 GM (m) 0.3 Worst Loading Condition: Full Load Departure Weight Increase Pct Weight Increase mt VCG m Lightship mt Loading Case VCG (m) Loading Case KM (m) GM Margin (m) GM Required (m) 0% 0 14.477 15,404 14.190 15.228 0.338 0.700 2% 308 18.300 15,712 14.217 15.223 0.306 0.700 4% 616 18.300 16,020 14.243 15.217 0.274 0.700 6% 924 18.300 16,328 14.268 15.211 0.243 0.700 2% 308 14.477 15,712 14.192 15.223 0.331 0.700 4% 616 14.477 16,020 14.194 15.217 0.323 0.700 6% 924 14.477 16,328 14.106 15.211 0.405 0.700 NOTE: GM = metacentric height; KM = height of metacenter above the keel; LBP = length between perpendiculars; m = meter; m-ABL = meters above baseline; mt = metric ton; pct = percentage; VCG = vertical center of gravity.

Next: Appendix D: Results of Lightship Weight Sensitivity Analysis for Selected Small Passenger Vessels »
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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