1195 Guidelines For The Conduct Of High-Speed Craft Model Tests

 

Ref. T4/3.01                                                                                                            MSC.1/Circ.1195

2 June 2006

 

 

1          The    Maritime      Safety     Committee,     at    its    seventy-third      session,     adopted,    by resolution MSC.97(73),theInternationalCodeofSafetyforHigh-SpeedCraft,2000(theCode) which,   following   the   entry   into   force   of   the   2000   SOLAS   amendments,   adopted   by resolution MSC.98(73), became mandatory as from1 July 2002.

 

2          Whiletheprovisionsofparagraph2.2.3.1oftheCoderequirethefittingofaninnerbowdoor onro-rohigh-speedcraftfittedwithbowloadingopening,theCoderecognizesthatexemptionfrom thisrequirementmaybegrantedinanumberofcaseswhicharestatedinparagraph2.2.3.2ofthe Code.  Oneofthesealternativesissetoutinparagraph2.2.3.2.2oftheCodewhichstatesthat,ifit can  be  demonstrated  that  a  craft  complies  withcertain  residual  stability  criteria,  even  ifwater accumulatesonthevehicledeckasaresultoffailureofthebowshelldoor,itmayqualifyforsuch anexemption.  ModeltestingisidentifiedintheCodeasoneoftheoptionsfordeterminingthe quantity of water that the craft in question may accumulate.

 

3          The  Committee,  at  its  seventy-fifth  session  (15  to  24  May  2002),  approved  Interim Guidelinesfortheconductofhigh-speedcraftmodeltests(MSC/Circ.1029)whichwereintendedto ensurethattheaforementionedmodeltestswouldbesufficientandadequatesothatrequestsfor exemptionareconsideredandgrantedinaconsistentandsafemannerwithoutjeopardizingthe safetyofthecraftandtoenabletheAdministrationtoconsultwitheachoftheportStatesbetween which the craft may operate.

 

4          The Committee further agreed that:

 

.1         theInterimGuidelinesshouldbeappliedwithaviewtoverificationandfurther developmentinthelightofexperience,andshouldberevisitedafteraperiodoftime not exceeding four years following the date of entry into force of the Code;

 

.2         comparativemodeltestsshouldbeconductedandtheresultsofsuchtestsshouldbe submitted  to  the  Organization,  so  as  to  validate  and  further  refine  the  Interim Guidelines; and

 

.3         MemberGovernmentsshouldundertaketoseekthecommentson,andevaluationof, theInterimGuidelinesfromtheInternationalTowingTankConference(ITTC)and, subsequently,collectinformationfromtheITTC,inparticulartheresultsoftheir experience,  and  submit  it  to  the  Organization  for  consideration  with  a  view  to improving the InterimGuidelines.

 

5          TheCommittee,atitseighty-firstsession(10to19May2006),approvedGuidelinesforthe conduct  of  high-speed  craft  model  tests,  prepared  by  the  Sub-Committee  on  Ship  Design  and Equipment at its forty-ninth session, revising the InterimGuidelines, as set out in the annex.                                                                           

 

 

 

6          MemberGovernmentsareinvitedtomakeuseoftheannexedGuidelinesandbringthemto theattentionofcraftdesigners,craftownersandotherpartiesconcerned,asappropriate,when considering the provisions of paragraph 2.2.3.2.2 of the Code.

 

7          ThiscircularsupersedestheInterimGuidelinesfortheconductofhigh-speedcraftmodel tests (MSC/Circ.1029).

 

 

 

 

***

 

Annex Guidelines For Model Testing

1 Introduction

 

1.1       The  exemption  from  the  requirement  to  fit  an  inner  bow  door  now  incorporated  in the2000HSCCode(paragraph2.2.3.2.2)maybeinvokedifacraftcanbeshowntocomplywith certainresidualstabilitycriteriaevenifwateraccumulatesonthevehicledeck(s)asaresultof failureofthebowshelldoor.  Modeltestingisoneoptionfordeterminingthequantityofwaterthat accumulates.

 

1.2       These  Guidelines  are  intended  to  ensure  that  such  model  tests  would  be  sufficient  and adequatesothattheexemptionwouldbeappliedsafelyandconsistently,andsothatthesafetyofthe craft would not be endangered.

 

1.3       Terms used in these Guidelines are as defined in the 2000 HSC Code.

 

1.4       The aimof the model tests is to determine the answers to two questions:

 

.1         whether waves reach the bow loading door; and, if so,

 

.2         what volume of water would accumulate.

 

1.5       To meet these aims, the following is described in these Guidelines:

 

.1         the use of towed or self-propelled models;

 

.2         physical  tests  at  heading  increments  of  45° relative  to  the  waves  at  zero  and  at forward speed;

 

.3         teststoestablishwhetherwaterreachesthebowopenings,andifsoteststodetermine the amount of water that may accumulate; and

 

.4         directmeasurementoftheaccumulatedvolumeofwaterattheendofeachtestrun,or determinationofthevolumebycalculationfrommeasurementsofrelativewater level within the vehicle space.

2 Model Design And Construction

2.1 Type And Size

2.1.1    Type of test facility

 

2.1.1.1   The  tests  described  by  these  Guidelines  are  intended  to  be  undertaken  in  either  a manoeuvringbasinorinheadandfollowingwavesinaconventionaltowingtank.  Themodelmay either be:

 

.1         towedfromacarriage(preferablyequippedwiththecapabilityforfree-to-surge under constant towing force), with freedomto heave, pitch and roll; or

 

.2         self-propelledandremotelycontrolled,eitherbyradioorbyalightweightumbilical attachment.

 

 

 

 

 

2.1.1.2   Thewavemakingfacilityshouldbecapableofgeneratingtherequisitespecificwave spectra with accuracy within + 2.5% on significant height,±2.5% on TP, and ± 5% on TZ.

 

2.1.2    Scale

 

Themodelscaleshouldbeaslargeaspracticablewithrespecttothetestfacilityemployed,butthe model should not be less than 1.5 min length, and be:

 

.1         appropriatetoenabletherequisitefullscalesignificantwaveheighttobegenerated;

and

 

.2         capableofprovidingtheequivalentofatleast1mindurationofoperationatfull scale per tank run at the maximumspeed to be tested.

2.2 Construction

2.2.1    General

 

The model should comply with the following:

 

.1            becapableofoperatinginbothdisplacementmodeandwhereappropriateinthe non-displacementmodeatarunningattitude(trimandsinkage)appropriatetothe full scale craft;

 

.2            anyliftdevices(e.g.,fans,foils,flaps,flexibleseals,wings,etc.)shouldgenerate forces,pressuresandvolumetricflowsresultinginthesamerunningattitudeincalm water,asspecifiedabove,ensuringabowheightaccuracywithin5%.   Actively controlledstabilizingorride-controldevicesshouldbeassumedtobeinafixed pre-set or passive mode;

 

.3            the   hull   should   be   suitably   thin   (0.01Lmodel    with   a   minimum   of   2 mm   is recommended) in floodable spaces;

 

.4            beequippedwithallmaindesignfeaturessuchaswatertightbulkheads,airescapes, freeingports,accesstrunks,etccorrespondingtothefullscalevehiclespaces,and modelled properly to represent the real situation as far as practicable;

 

.5            beconstructedwithsuperstructurestotheextentneededtoensurearealisticresponse in waves;

 

.6            besuitablyconstructedtopermitmonitoringoftheinteriorofthefloodablespaces, using video cameras;

 

.7            beequippedwithexternalappendagessuchasbilgekeels,sprayrails,liftdevicesor fendering as may reasonably be expected to influence the results of the tests;

 

.8            beprovidedwithabowaperturetoaccuratelymodelthefullscalecraftafterthebow loading door(s) may have been lost, specialattentionbeingpaidtothefreeboardat the lowest point;   

 

 

 

 

 

.9            beequippedwithfast-closingwatertightshutterstothebowaperture(s)andany drainageopeningsthatcanberemotelyopenedandclosedatthebeginningandend of the test period during each run;

 

.10          prior   to   ballasting,   the   model   should   be   equipped   with   all   the   necessary instrumentation; and

 

.11          freeingportsandothermeansofdrainageshouldbeclosedatalltimesduringthe tests.

 

2.2.2    Permeability of vehicle spaces

 

Thereductionofpermeabilityofthevehiclespacesduetothepresenceofcargoshouldnotbe represented.

 

2.2.3    Accuracy

 

2.2.3.1   Themassofthemodelafterballastingtothedirectlyscaleddesignwaterlineshouldbe within ±1% of that representing the full scale craft.

 

2.2.3.2   Thelongitudinalcentre-of-gravityafterballastingtothedirectlyscaleddesignwaterline should result in a static trimattitude within 0.2° of that representing the full scale craft.

 

2.2.3.3   Thevolumeofthevehiclespacestothefirstdownfloodingopeningderivedwhenthecraft isatthedesignedtrimattitudeshouldbewithin±2%ofthatrepresentingthefullscalecraft.  Where openvehiclespacesaremodelled,thevolumeshouldbemeasureduptothelevelatwhichwater might  first  begin  to  spill  out,  or  alternatively  the  deck  area  should  be  within  ± 2%  of  that representing the full scale craft (commensurate with hull thickness as specified in 2.2.1.3).

 

2.2.3.4   Thefreeboardfromthedirectlyscaleddesignwaterline(atzerospeed)tothelowestpointof the bow loading opening should be within +0 to -1% of that representing the full scale craft.

2.3 Model Loading

2.3.1    Ballasting  particulars  should  be  developed  for  one  loading  condition  prior  to  testing, viz:maximumoperationalweight(asdefinedinthe2000HSCCode),combinedwiththemost onerousbowdownrunningtrim ortheconditionwiththebowapertureclosesttothewaterinthe running trim.

 

2.3.2    The ballasting particulars should be such as to achieve:

 

.1         a mass corresponding to the loading conditions defined above;

 

.2         averticalcentre-of-gravitypositioncorrespondingtothemaximumallowablein service  (limiting  KG)  for  the  respective  operational  weight,  or  alternatively  the maximumpredicted operational KG plus a margin of 10%;

 

.3         longitudinal  centre-of-gravity  positions  corresponding  to  the  nominal  and  most forwardandmostaftpositionsenvisagedbytheloadingrestrictionscontainedinthe craft operating manual;   

 

 

.4         a  longitudinal  radius  of  gyration  equivalent  to  that  calculated  for  the  full-scale craft±8%,or(wherethisinformationisnotavailable)withintherange0.23to0.27L, where L is as defined in the 2000 HSC Code; and

 

.5         arollradiusofgyrationequivalenttothatcalculatedforthefull-scalecraft±8%,or (wherethisinformationisnotavailable)withintherange0.35to0.4B,whereBisas defined in the 2000 HSC Code,  after ballasting for each condition:

 

.6         the total model mass should be verified by weighing;

 

.7         the  actual  vertical  centre-of-gravity  and  longitudinal  trim  should  be  verified  by physical inclining in air and/or water;

 

.8         the longitudinal and roll radii of gyration should be verified in air; and

 

.9         thenaturalrollperiodshouldbemeasuredbyarolldecrementtestwiththemodelat rest in calmwater.

3 Environmental Conditions

3.1       Waves

 

3.1.1    Twoseastatesshouldbeused.Themodelshouldbetestedinalong-crestedirregularseaway atmaximumsignificantwavesteepnessofHs/(gTp2/(2ð))=0.05.  Intheabsenceofinformationon specific  spectrum  data,  JONSWAP  type  spectra  should  be  used  with  a  peak  enhancement factor  ã=3.3.  Inthefirstseastate,Hs shouldbethemaximumsignificantwaveheightfortheareaof operation,whichisnotexceededbyaprobabilityofmorethan10%onayearlybasis,butlimitedto a  maximum  of  4  m.   In  the  second  sea  state  Hs  should  represent  the  significant  wave  height corresponding to the most onerous relative bow motion (worst intended conditions).

 

3.1.2    Generationofthewavesshouldbesuchthateachwaverealizationresultsinanon-repeating wave train during the model test.

 

3.2       Wind

 

Wind should not be represented during the tests.

 

4 Instrumentation, Calibration And Data Recording

 

4.1 Model Instrumentation

4.1.1

The  following  model  instrumentation  should  be  provided  as  a  minimum:  one

relative

water levelsensorlocatedinfrontoftheopeningattheportandstarboardextremitiesoftheopening

(i.e. 2 sensors).

 

 

4.1.2    Ifthewatervolumeistobeestimatedusingwaterheightmeasurements,15waterlevel sensorsshouldbeusedatthefollowinglocations(wherel =thelengthofthefloodablevehicle space):

 

.1         at10%ofl fromthebowloadingopening,atthewatertightboundaryontheportand starboard sides and centreline (h FP, h FS  and h FC  respectively);

 

.2         at30%ofl fromthebowloadingopening,atthewatertightboundaryontheportand starboard sides and centreline (h FMP, h FMS  and h FMC  respectively);

 

.3         at50%ofl fromthebowloadingopening,atthewatertightboundaryontheportand starboard sides and centreline (h MP, h MS  and h MC  respectively);

 

.4         at30%ofl fromtheaftlimitofthevehiclespace,atthewatertightboundaryonthe port and starboard sides and centreline (h AMP, h AMS  and h AMC  respectively); and

 

.5         at10%ofl fromtheaftlimitofthevehiclespace,atthewatertightboundaryonthe port and starboard sides and centreline (h AP, h AS  and h AC  respectively).

 

4.1.3    A drawing of the positions of the water height sensors should be provided.

 

4.1.4    Instrumentation to measure roll and pitch angles and heave motion is recommended.

 

4.1.5    If the testing is conducted solely to demonstrate that water does not reach the bow loading opening, then all items except 4.1.1 may be omitted.

 

4.1.6    Asanalternativetotheuseofwaterlevelsensorsdescribedin4.1.2above,thevolumeof wateraccumulatedduringatestrunmaybedeterminedbydirectcollectionandweighingofthe water inside the model.

 

4.2 Facility Instrumentation

The following instrumentation should be provided in the model basin:

.1 one static wave height probe located clear of tank end effects;

.2 one moving wave height probe mounted so that it approximately matches the mean model position;

.3 mean forward speed of the model; 

.4 video camera(s) to monitor the interior of the vehicle spaces; and

.5 video camera(s) to monitor the exterior of the model, especially the bow aperture.

4.3 Data Recording

Continuous records should be obtained for all the media required by 4.1 and 4.2 for each test run, with a sampling rate at model scale of not less than 25 Hz.

5 Test Procedure

5.1 Preparation

5.1.1 The model should be prepared in accordance with 2.2, 2.3 and 4.1 above, and all verification checks required by 2.1 to 2.3 should be completed before testing commences.

5.1.2 The wave spectra should be run and verified for compliance with the requirements in 2.1.1.

5.2 Craft Speed And Operating Mode

5.2.1 Where a craft normally operates in a non-displacement mode, tests should be conducted in both zero speed (displacement mode) and maximum operating forward speed (non-displacement mode). Where a non-displacement mode is tested, any lift devices should be employed as specified in 2.2.1.1.

5.2.2 Prior to the testing, an estimate should be made by the owner and/or builder as to the maximum speed of the full scale craft into head seas (VW) that would be practically attainable in the specific loading condition (powering considerations) or be structurally permissible (e.g.: by the classification society). Where a craft may be operated in both displacement and non-displacement modes, separate values of VW should be derived for the two modes.

5.2.3 In head seas the speed of the model should not exceed V W , but may be reduced to not less than 65% of V W , provided that if a reduced speed is necessary to satisfy the terms of the exemption, the maximum permissible speed in the relevant wave height is incorporated in the Permit to Operate and in the craft operating manual.

5.3 Test Run Procedure

5.3.1 Once the craft has reached the required test speed during a tank run, the watertight bow aperture(s) are to be rapidly opened and are to remain open until the point at which the model is decelerated at the end of the run. At that point the watertight shutters are to be rapidly closed to trap the water collected inside the model. This water is to be measured directly after the tank run (5.5.3 refers) and the water is to be removed from the model after each run.

5.3.2 A weight made of high density material, such as lead or steel, equal to the mass of water collected at the end of each tank run is then to be placed on the vehicle deck, on the centreline of the craft and at the longitudinal mid point of the vehicle deck. This weight should be cuboid in shape, with length and beam selected to fit the available deck space, aiming not to restrict the water flow on the vehicle deck. This may allow for more water to accumulate on the ro-ro deck than what would be the case in one continuous run but this error is likely to be small and on the side of safety.

5.3.3 This process is to be repeated for each run of a test case.

5.4 Test Programme

5.4.1    General

 

5.4.1.1   ThetestprogrammeshouldbewitnessedbyanAdministration(wheneverknown,this shouldbetheflagAdministration),surveyorsnominatedbythemforthepurposeorbyorganizations recognized by them.

 

5.4.1.2   Thetestprogrammeshouldbeconductedforthecraftoperatingineachoftheseastates stipulatedin3.1abovethroughdirectphysicaltestingatzeroandforwardspeedonfiveheadings relative to the wave direction, between head and following seas in 45 degrees increments.

 

5.4.2    Duration and repetition of test runs

 

5.4.2.1   Fortestrunsatzerospeed,eachrunshouldhaveadurationof10min(fullscale).Eachtest case at each heading should consist of a set of three tank runs with different wave realizations.

 

5.4.2.2   Eachtankrunatforwardspeedshouldbeofthemaximumpracticalduration,inanycase notlessthantheequivalentof1minatfullscale,withthebowopeningshutterbeingopenedand closedatthebeginningandendofthetestperiodofeachrun.   Eachtestrunshouldcomprise successivetankrunstorepresentnotlessthan10minofcontinuousfullscaleoperationinonewave realization at a given heading angle.

 

5.4.2.3   Eachtestcaseperheadingangle(atforward speed) should consist of an ensemble of test runswithdifferentwaverealizations.Thenumberofassociatedwaverealizationsshoulddependon the heading angle as follows:

 

.1         three wave realization trains in head and bow quartering seas;

 

.2         four wave realization trains in beamseas; and

 

.3         five separate wave realization trains in following and stern quartering seas.

 

5.4.2.4   Eachwaverealizationtrainwillbeofatleast10minfullscaletotalduration,eachsuch wave train being taken fromthe required wave spectrum.

 

5.4.3    Tests in waves at all heading angles

 

5.4.3.1   Asaminimumthefollowingtestsshouldbeconducted:ataspeedofVW anddesignLCG, tests in waves specified in 3.1.

 

5.4.3.2   Ifthecraftdoesnotcomplywiththewatervolumerequiredtomeettheexemption,thenthe tests can be repeated at lower speed to a minimumof 65% Vw.

5.5 Test Results

5.5.1    General

 

The tests are required to determine the answers to two questions:  

 

 

.1         whether the bow loading door is reached by the waves; and, if so,

 

.2         what volume of water would accumulate.

 

5.5.2    Determination of whether water reaches the bow opening

 

If,duringtheconstantspeedportionofANYofthetestrunsrequiredbytheseguidelines,wateris observedormeasuredashavingexceededtheloweredgeofthebowopening,thentherequirement ofthe2000HSCCode,paragraph2.2.3.2.2.1(objective5.5.1.1)shouldbedeemedNOTtohave beensatisfied.  Intheeventthisisnotsatisfied,thenanexemption maystillbepossiblebyfurther teststodemonstratecompliancewiththe2000HSCCode,paragraph2.2.3.2.2.2(objective5.5.1.2).

 

5.5.3    Determination of volume of water

 

Fromthe modelteststheaccumulatedvolumeofwaterforeachheadingangle maybedetermined by:

 

.1         directmeasurementoftheaccumulatedvolumeofwaterbycollectingthetrapped water  on  the  vehicle  deck  in  a  measurement  receptacle  (preferred  method). The watervolumecollectedduringeach(10min)testrunshouldbebasedonthesum ofvolumesrecordedforeachsuccessivetankrun.   Foreachtestcaseatagiven headinganglethevolumeshouldbeaveragedoverthevolumesofthedifferenttest runs(waverealizations)togiveacollectedvolumefora10min(fullscale)time period; or

 

.2         determinationofthevolumebycalculationfrommeasurementsofwaterlevelwithin thevehiclespace,usingthemethodof5.5.4below.  Thepositionofthesolidweight aftereachrunshouldbepositionedtominimizeinterferencewiththewaterheight measurement probes.

 

5.5.4    Calculation of volume of water accumulating on the vehicle deck

 

5.5.4.1   Whenthevolumeofwateraccumulatedonthevehicledeckisestimatedfromwaterheight sensors,itshouldbecalculatedasfollows.  Themeanvolumeofwaterduringeachsuccessivetank runshouldbedeterminedfromthefifteensensorsasdefinedin4.1.2.1to 4.1.2.2.Themeanheights

ofwatermeasuredattheselocationsshouldbescaledtofullscalebeforecalculatingthevolumeof water as follows (where the symbol h¿ denotes the water height scaled as described above).

 

 

5.5.4.2   Volume of water during tank run i:

 

Voli  =  A VD (h¿ FS  + 2h¿ FC  + h¿ FP  + h¿ FMS + 2h¿ FMC +h¿ FMP +h¿ MS +2h¿ MC +h¿ MP +h¿ AMS +

2h¿ AMC  + h¿ AMP  + h¿ AS  + 2h¿ AC  + h¿ AP) / 20                    (m3)

 

Where: A VD  = plan area of vehicle deck capable of being flooded (m2  at full scale).

 

5.5.4.3   ThevolumeofwateraccumulatedduringatestrunisgivenbythesumofVoli  foreach successive tank run.

 

5.5.5    Volume of water to be used in calculating residual stability

 

The  volume  of  water  resulting  from  the  most  onerous  condition  (i.e.,  heading  angle)  obtained from5.5.3.1or.2istobeusedforcalculatingthestabilitypropertiesfordemonstratingcompliance with the 2000 HSC Code, paragraph 2.2.3.2.2.2.

5.6 Test Report

The test report should include the following information as a minimum:

 

.1         generalarrangementdrawingofthecraft,showingthespacesthatmightbeflooded as a result of failure of the bow loading door;

 

.2         generalarrangementdrawingofthemodel,showingthescaleratioanddetailsofthe construction and instrumentation;

 

.3         calculations  to  show  the  derivation  of  the  maximum  operational  and  minimum operational weights and corresponding limiting KG positions;

 

.4         tests conducted to verify the mass, centre-of-gravity position and radii of gyration;

 

.5         whereappropriate,calculationstoshowthattheelementsnecessarytoachievethe non-displacement mode have been appropriately scaled;

 

.6         the nominal and measured wave spectra (at the fixed wave probe location); and

 

.7         records for each test case:

 

.7.1      wave elevation at model position;

 

.7.2      relative wave height at the opening; and

 

.7.3      internal water volume measurements.

• Informatietype: Internationaal
• Documentsoort: Circulaire niet in wetten.nl
• Toegangsrechten: Extern
• Identificatie: PUC_1883_14
• Versie: 1
• Datum beschikbaarheid: 07-11-2007
• Geldigheid van: 06-02-2006
• Wijzigingsdatum: 24-11-2016
• Titel: 1195 Guidelines For The Conduct Of High-Speed Craft Model Tests
• Organisatie: International Maritime Organization (IMO)
• Taal: Nederlands
• Onderwerp: Veiligheid / Safety
• Hoofdtaak: Koopvaardij / Merchant Shipping
• Thema: Zeevaart / Seagoing ships / Information / IMO Instruments (Informative) / Circulars (Informative) / MSC Circulars (Informative) / 1100 until 1199