design considerations for aluminum hull structures - Ship Structure ...

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TABLE 22 Trim and StabilityFull Load Departure Condition (Homogeneous Cargo)TABLE 23 Trim andBallast - ArrivalSTEEL SHIP ALUIIINUI[SHIPm. — _ VCG _ ICG iiT. — VCG — ~Light Ship 7,892 33.4 hO.9A .5’,20035.00 63.OACrew& Misc.Mt. 200 36.o I89.3A 202 36.0 189.3AFuel 1,029 6.8 159.5A 1,029 6.8o 159.5AFreshWater 282 h4.7 ‘257.1A 282 44.70 257.1ACargo 35,849 28.8 31.OF 38,!li 28,80 31.m?FULL IfJIDCONDITIONDraft at TXFKHKGGM Uncorrect~F.S. CorrectionG.1,1.Correcte5LCBICGLVR~q 11lkrimDraft FudDraft Aft45,252 29.2 llJ!F361-11 -~/81136.10929.2’6.90~O,)lo!6,50’12.71 l%dll.b I fi~d1.3’ Aft4,5041Tons13” By Stern36r-S-I/8r’371-6-J/811IJ5,25229.14361-11 -5/8”36.10’29.lh’6.961O.bor6.56112.71Fwd13.11FwdO.hnFM4,50b’Tonsbr’By Bow37I-1-5/81’361-9-5{8”13.IFItemSTEELSHIPWT. —. V02 — LCGLight Ship 7,892 33.4 lJO.9Crew & Mist, Dwt 200 36.0 189.3AMel 80 12.85’ 190.OAFresh Water 30 b6.70 2116.7S.W. Ballast 11,369 29.Oh 23.6BALMST CONDITION 19,571 30.8 5.9Draft At LCFKMKGGM UncorrectedFS CorrectionGM CorrectedLOBJIGLTCRMT1 “TrimDraft WdDraft Aft~bf-~olt4h.7’30.8713.92.311.6’19.21F5.91A25.1‘A3,628’Tons111-3-1/2” By Ste1 ~ 1-5-3/~112zr-9-I/~11++ Used No. 4 Hold for additional ballast ca+$+$includes Full F.S. for No. 4 Hold (4.41),
.97-Iv.COST STUDIESOBJECTIVESThe objective of these studiesan existing steel bulk carrier withover-all dimensions to determine ifwas to compare the life cycle costs ofan aluminum hulled ship of the samethe higher first cost of the aluminumhull can be justified on the basis of long-term economics, including extendedship life.METHOD OF ANALYSISThe initial step was to prepare single ship price estimates using anexisting computer model based upon a vessel life of 20 years. The pricefor a steel bulk carrier tifthe CHALLENGERIS characteristicswas determinedfor construction in a U.S. shipyard in 1970. The steel ship price was thenused as a reference in determining a price for the aluminum ship. Copiesof the ship price breakdowns are included as Tables 24 and 2?J,which includenotes to explain the de~ivation of cost details. The aluminum ship costs arenot applicable to a prototype ship, but assume a state-of-the art equivalentto steel. A single prototype would undoubtedly cost far more, due to requirementsfo~ personnel training, contingencies,greater testing and development,and other factors beyond the scope of this study.Next, data was gathered on fixed and variable operating and maintenancecosts applicable to the two ships and the compvter model was modified accordingly.This data appears as the Assumptions on Table 26.Computationswere made to determine the required freight rate (RFTljthestandard economic measure of merit used) on realistic voyages fox fifty-fourseparate c~ses, using the model. The RFR is based upon present values ofvessel life cycle costs and includeg a 10 per cent after tax return on investmentto the Owner. The first thirty-si’xcases were based upon two of thefour leg dry bulk carrier voyages which were represented in the previous drybulk carrier study for the Maritime A~inistration, Reference (70). Resultsof these computations appear on Table 27. The cases which were studied includedconstruction of steel and aluminum ships in flights of 1, ~ and 10and ship life of 20, 2S and 30 years.The procurement costs for aluminum and steel vessels with lives in excessof 20 years were increased from the baseline figuresin Tables 24 and 25as follows:(1) The aluminum hull structure was assumed tobe satisfactory fora 30 year life without modification.(2) The steel hull struct~e was assued tobe satisfactory fora life of 2S years without plate renewal, based upon discussionswith American Bureau of Shipping. Two methods are thereforeopen to extend the hull life to 30 years: provide greater platethickness initially so that the net plate thickness at 30 years5s marginally satisfactory, or renew excessively corroded plateat 2S years. ‘Thefirst approach was chosen, and one-sixteenthinch was added to the immersed sh~l plating throughout, whichwould extend the shell life ~ years, based on an average corrosionrate of .01 inches per year. This increases the light ship weight90 tons, with a corresponding increase in cost and reduction in
Page 5:
CONTENTSI.. II.III.Iv.v.VI ●VII.I
Page 9 and 10:
LIST OF FIGURES(Cent’d)FIGURE NO.
Page 11 and 12:
I. INTRODUCTIONThis report summariz
Page 13:
art in fabricating and maintaining
Page 16 and 17:
MONTEROSSO GRANA /17VALGRANA / CARA
Page 18 and 19:
-8-Numerous references have been re
Page 20 and 21:
.10.TABLE 2. Mechanical Properties
Page 22 and 23:
TABLE 2 Mechanical Properties of Al
Page 24 and 25:
TABLE 3 Mechanical Property Limits
Page 26 and 27:
-16-l?igures5, 6, 7 ati 8 present f
Page 28 and 29:
-18-ti-’”’-”-””””-L
Page 30 and 31:
-20-60 .r---.— ..,.— -——,L-
Page 32 and 33:
.22-each stress level, rate of load
Page 34 and 35:
-24-!Z456-H321 = 0.485083-H321 = 0.
Page 36 and 37:
-26-(c)Members with partial or cont
Page 38 and 39:
-28-AllOyS 5083 and 54.56(~ content
Page 40 and 41:
-30-The previous paragraphs have de
Page 42 and 43:
-32-The problem of cargo hold abras
Page 44 and 45:
-34-The question of residual stress
Page 46 and 47:
.36-Each alloy was given a relative
Page 48 and 49:
-38-GENERAL OBSERVATIONSFYior to a
Page 50 and 51:
-40-The question of comparative imp
Page 52 and 53:
-42-(d)(e)Poor quality welds due to
Page 54 and 55:
-44-The ABS criteria noted above we
Page 56 and 57: -46-DNV would consider fatigue in e
Page 58 and 59: -48-is less, for the exposed side s
Page 60 and 61: Equation (2):-50-Hu1l SMa~um = Hull
Page 62 and 63: -52-Another aspect of vibrations wh
Page 64 and 65: -54-000000000Bottom Shell PlateSide
Page 66 and 67: -56-at the deck and keel. This stre
Page 68 and 69: -58-AT is the change inUT= Thermal
Page 70 and 71: -60-SUl@!ARYAll parties contacted f
Page 72 and 73: -62-(c)(d)(e)(f)T~e exterior side o
Page 74 and 75: TABLE 12 Aluminum Bulk Carrier - Su
Page 76 and 77: .66-INSUT.ATION AND SHEATHINGShell8
Page 78 and 79: -68-(b)(c)(d)(e)(f)(g)(h)(i)(j)At l
Page 80 and 81: -70-IIF.INSTALLATION OF SYSTEMS AND
Page 82 and 83: Rudder Assembly -carrier should be
Page 84 and 85: -74-(b)MechanicalTensile Strength 6
Page 86 and 87: -76-(e)The steel piping must be of
Page 88 and 89: -78-Other Piping Systems and Valves
Page 90 and 91: -80-struetion for the aluminum hull
Page 92 and 93: -82-Large heavy type machine~ must
Page 94 and 95: suffers attack in an alkaline envir
Page 96 and 97: -86-REPAIRSObtaining proper repairs
Page 98 and 99: -88-The design of the midship s~cti
Page 100 and 101: -90-assuming the increase is applic
Page 102 and 103: LIGHT SHIP WEIGHT ESTIMATE-92-In or
Page 104 and 105: -94-TABLE 20 Aluminum Bulk Carrier
Page 108 and 109: -98-TABLE 24 Price of Steel Bulk Ca
Page 110 and 111: GaseNumber. . . -.,- .TABLE 27 Comp
Page 112 and 113: -1o2-TABLE 28CarriersComparison of
Page 114 and 115: 12 ---n..T.[T7%l,=LEGS IU ORF=ErY
Page 116 and 117: -106-such as iron ore, on two of th
Page 118 and 119: -108-7)is,zg~ gg~5e mzz~E’4E!~K2j
Page 120 and 121: -11o-(a)(b)(c)(d)Inerting system fo
Page 122 and 123: -112-fatigue, particularly in the p
Page 124 and 125: -114-2k* Installation of Systems an
Page 126 and 127: -116-LIST OF REFERENCES(7)Fatigue P
Page 128 and 129: -11.8-LLST OF REFERENCES(Cent’d)(
Page 130 and 131: -120-ADDITIONAL SOURCES OF INFORMAT
Page 132 and 133: -122-redistribution of the still wa
Page 134 and 135: -124-APPENDIX BEXCERPTS FROMRULES A
Page 136 and 137: -126-92.07-10(d)(~) Interior stairs
Page 138 and 139: -128-~gE1+0102030- .. ..—405060
Page 140 and 141: ectintyclassification4KEYWORDSROLEL
Page 142: SHIP STRUCTURE COMMITTEE PUBLICATIO
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