1、Designation: F3052 14Standard Guide forConducting Small Boat Stability Test (Deadweight Surveyand Air Inclining Experiment) to Determine Lightcraft Weightand Centers of Gravity of a Small Craft1This standard is issued under the fixed designation F3052; the number immediately following the designatio
2、n indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.INTRODUCTIONSmall craft operators, builders, buy
3、ers, accident investigators and others may be required todetermine the centers of gravity for their craft in order to apply stability criteria or perform otheranalyses. The conventional in-water stability test can be difficult to perform accurately on small craft,so an in-air inclining experiment ma
4、y be specified. However, there are no guidelines available to helpstandardize and explain the process.This guide provides the marine industry with an understanding of an Air-Incline stability test forsmall craft. It contains procedures to ensure that valid results are obtained with precision at a mi
5、nimalcost to owners, shipyards and the government. The guide is not intended to direct a person(s) in theactual calculations of the lightcraft weight and centers of gravity, but to be a guide to the recommendedprocedures required to gather accurate data for use in the calculation of the lightcraft c
6、haracteristics.A complete understanding and documentation of proper procedures to conduct a stability test isparamount to confirm that the results gathered during the test can be examined for accuracy, especiallyby third parties subsequently reviewing the data. This guide is recommended to be used f
7、or all smallcraft capable of being lifted safely with forward and aft pick points capable of enduring additionalinclining weights to be used for the stability test.1. Scope1.1 This guide covers the determination of a small boatslightcraft characteristics. The air incline stability test can beconside
8、red two separate tasks; a deadweight survey and anair-inclining experiment. The stability test is recommended,but not required, for all small craft upon their constructioncompletion and/or after major conversions where stabilityinformation is required. It is typically conducted indoors andan enclose
9、d facility to protect the vessels from unprotectedenvironmental conditions.1.2 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determin
10、e the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2F1321 Guide for Conducting a Stability Test (LightweightSurvey and Inclining Experiment) to Determine the LightShip Displacement and Centers of Gravity of a Vessel3. Terminology3.1 Definitions:3.1.
11、1 inclining experimentcomprises moving a series ofknown weights in a transverse direction and then measuring theresulting change in the equilibrium heel angle of the craft. Thisinformation is used to calculate the vessels vertical center ofgravity.3.1.2 lightcrafta small craft, or boat in the lighte
12、st condi-tion (“Condition 1”) is a boat complete in all respects withoutconsumables, stores, cargo crew and effects and without any1This practice is under the jurisdiction of ASTM Committee F25 on Ships andMarine Technology and is the direct responsibility of Subcommittee F25.01 onStructures.Current
13、 edition approved Jan. 1, 2014. Published February 2014. DOI: 10.1520/F3052-14.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page o
14、nthe ASTM website.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1liquids on board except machinery fluids, such as lubricantsand hydraulics at operating levels. The lightcraft should be asdefined in the craft procurement or other spe
15、cifications, or inthe operating manual, as to outfit permanently aboard, etc.3.1.3 deadweight surveycomprises weighing the vessel attwo longitudinal points to determine the total weight andlongitudinal center of gravity of the craft, then auditing allitems found on board to be added, deducted or rel
16、ocated on thecraft at the time of the stability test so the observed conditionof the small craft can be adjusted to the specified lightcraftcondition. All loose items or outfit equipment (that is, anchor,anchor warp, dock lines, fire extinguishers, etc.) found onboard should be removed completely fr
17、om the craft andweighed separately on a calibrated scale.3.1.4 keel (baseline)the datum point used for measuringthe vertical location of the pivot points and subsequentlydefining the vertical location of the weights involved in thetest. It is often the lowest point of the craft hull, but may bedefin
18、ed as any convenient point, provided it is consistentwithin the experiment, consistent with any other documenta-tion such as the drawings or weight estimate, and welldocumented.3.1.5 Stern Reference Point (SRP)the intersection of thetransom and the keel (baseline) of the boat or as otherwisedefined
19、in the documentation, but should be clearly defined anddocumented in the test report, and should be verified byphysical measurement at the time of the test relative to the liftpoints. The SRP is where all relative locations of outfit andcenters of gravity should be referenced in Fig. 3.3.1.6 X1longi
20、tudinal distance from stern reference point(SRP) to aft pick point.3.1.7 X2longitudinal distance from stern reference point(SRP) to forward pick point.3.1.8 Xlongitudinal distance from stern reference point(SRP) to longitudinal center of gravity of the boat.3.1.9 W1weight in pounds at the aft pick p
21、oint.3.1.10 W2weight in pounds at the forward pick point.3.1.11 WW1+W2, is total weight of the boat.3.1.12 Bvertical distance from SRP to pick points and rollaxis/centerline of knife edges.3.1.13 LCGlongitudinal center of gravity measured fromthe SRP.3.1.14 VCGvertical center of gravity measured fro
22、m thebaseline.3.1.15 Tan tangent angle of deflection.4. Significance and Use4.1 From the lightcraft characteristics, calculations of thestability characteristics of the small craft for all load conditionscan determine compliance to applicable stability criteria orprovide mass properties information
23、for other analyses orinvestigations.Accurate results from an air incline stability testmay therefore determine future survival of the boat, the crewand compliment. If the small craft is not 100 % complete orthere is fuel or other liquids in a tank that is supposed to beclean and dry then the person
24、leading the stability test mustdetermine the acceptability of all variances from the guidebased on the ability to correct for these variances analytically.A complete understanding of the principles behind the stabilitytest and knowledge of the factors that affect the results istherefore necessary.4.
25、2 The results of the stability test typically supersede thecorresponding values in the weight estimate for any subsequentuse in ascertaining compliance to stability or weight controlcriteria and may be used in weight margin adjudication.FIG. 1 Typical Incline PlotF3052 1425. Theory5.1 This test is a
26、nalogous to the standard in-water incliningtest of Guide F1321 and the basic concepts are similar, but theinformation determined by the readings of the scale(s) and thelocation of the pivot point are substituted for the hydrostaticproperties of the floating vessel in an in-water incliningexperiment.
27、 Similar terms are used in some cases based on thisanalogy, but these terms should not be confused with thosederived from hydrostatic data.5.2 The MetacenterThe transverse metacenter “M” is thepoint around which the boat swings through small angles ofinclination (typically 0 to 5). This is the point
28、 at whichtransverse movement is not constrained relative to the crafthull. For example, as shown in Fig. 5, the lift straps constrainthe lower shackle from moving transversely relative to the crafthull, but there is no such constraint on the upper shackle, so thelower shackle pivots on the contact s
29、urface between the upperand lower shackles and the metacenter is at their mutualcontact point, The height of “M” above “K” is known as“KM”. The location of M is fixed over the range of angles ofinclination during the stability test. The intersection betweenthe bearing surfaces of the shackles is kno
30、wn as the “knife-edge”. It is imperative that this height, “KM”, be exactlyparallel between the forward and aft pick points and theFIG. 2 Measurement of KM, GM aregular round bucket is generally acceptable.6.4.4 Aweighted winged pendulum bob (such as two anglesconnected at their heels) should be imm
31、ersed in a trough filledF3052 147with a liquid to dampen oscillations after each weight move-ment. Liquid detergent generally works well. The troughshould be deep enough to prevent the pendulum bob fromtouching the bottom.6.4.5 Battens used to record the readings should be smooth,easy to read and se
32、curely fixed in position so that an inadver-tent contact will not create a bad reading. They should bemarked with a horizontal datum line that defines the lowerpoint of the vertical height of the pendulum. The battens shouldbe aligned close, but not touching the pendulum. The deflectionused to calcu
33、late the inclining angle comprises the location ofthe pendulum string where it crosses the datum line of thebatten. This is recorded on battens which may comprise a scalefor noting the deflections or a mark able surface. If necessary,a mirror or other reflective surface one or behind the battenmay b
34、e used to visually align the pendulum line and its imageand thereby correct for any error due to misalignment.6.5 Water Tubes:6.5.1 Water tubes may be substituted for pendulums;however, at least one pendulum must be used for the test.6.5.2 At a minimum, three (3) water tubes should bearranged to all
35、ow personnel to read and record deflectionscaused by the weight shift during the stability test on either sideof the boat. Like the pendulum, the greater the span betweenthe vertical ends of the water tube apparatus, the higher thedeflection readings when shifting the weight. Water tubesshould be ar
36、ranged to give equivalent measurement precisionas a pendulum. Water tubes should be located forward, midshipand aft.6.5.3 The flexible water tubes should be long enough to layfreely athwartships on the boat and extend vertically on theends of an apparatus, see Fig. 7. The tubes should not come incon
37、tact with the ground.6.5.4 Make sure the water tube is free of any air bubbles.Trapped air bubbles will cause an error in the deflectionreadings. Generally, when using three water tubes in parallelwith one another, different colored dye is added to each watertube to allow personnel recording the def
38、lections to do sowithout discrepancy. This also ensures that the port andstarboard legs of the tube are correctly matched. Note that astopcock on each end of each tube allows them to be moved orotherwise inclined without loss of the fluid, but verify that thestopcocks are fully open during each meas
39、urement.6.5.5 Rulers or battens should be fixed to the vertical ends ofthe water tube apparatus to easily read the deflection in thewater tube, as shown in Fig. 8. Measurements of the deflectionsrecorded must be readable to116 in. and a minimum of 6 in. ofdeflection must be attained above and below
40、the zero point oneach side of the vessel.6.5.6 The water tube apparatus is usually located in anunobstructed section of the boat deck where it can pass freelyfrom side to side. Note that the tube connecting the water levelsmay run freely vertically and fore and aft, etc. as convenientprovided that n
41、o point on the tube is higher than the measure-ment area and that no air pockets are formed.6.6 Digital Inclinometers:6.6.1 A calibrated digital inclinometer may be used forquick reference validation and not to substitute the pendulumsor water tubes. They should be located with the active axisathwar
42、tships and in an unobstructed area easily viewed bypersonnel to record. They should have a precision equivalent toat least 60.01 degrees and an accuracy of 60.05 degrees. If thereading does not stabilize at a single number, an average of atleast five maximum-minimum swings (therefore, ten readings)s
43、hould be recorded for each weight movement.6.6.2 Manufacturers data or certification for the inclinom-eter must also be submitted.6.7 Laser Level:FIG. 7 Typical Water Tube ArrangementsF3052 1486.7.1 A laser level can be used during a stability test tocheck for even trim of the boat.6.7.2 A laser tra
44、nsit can be used to assure the knife-edgepick points and the boat baseline are level and parallel.6.7.3 A laser level or optical transit can be used fordetermining the inclination of the boat. If used this should beonly one of at least three independent means of determining theFIG. 8 Typical Water T
45、ube Deflection Recording StationF3052 149inclination of the boat and should be shown by calculation togive equivalent precision to 0.1 % slope.6.8 List and TrimThe most crucial procedure for thestability test is to ensure that the boat should be as close aspossible to even trim and list hanging from
46、 fore and aft cranes.A water tube or laser transit can be used to ensure the boat islevel and that the fore and aft pick/lift points are the exactdistance from the baseline. With inclining weights in the initialposition, up to12 of list is acceptable. If the list exceeds theacceptable limit, use lev
47、eling weights to put the vessel at anacceptable condition.6.9 Communication Arrangements:6.9.1 One person at a central location within the stabilitytest facility should have ultimate control over all personnelinvolved with the test.6.9.2 If necessary, efficient two-way communications be-tween centra
48、l control and weight handlers and central controland data collectors.6.9.3 Ultimately, the stability test should be administeredindoors in an enclosed facility with no less than two cranes toavoid any environmental effects (that is, wind, rain, etc.) duringthe test; however, if an enclosed facility
49、cannot be provided, atest can be satisfactorily administered outdoors in calm condi-tions (that is, no wind, no rain, etc.). The test leader shoulddetermine the results satisfactory by monitoring the plot andnoting any major deflections or errors.6.10 General:6.10.1 If the person administering the test desires to substi-tute inclinometers or other measuring devices for pendulums orwater tubes, they should complete prior testing of the measur-ing devices to verify their accuracy. It is recommended thatsuch devices be used in conjunction with at least on
