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

SIGNIFICANCE AND USE
4.1 From the light ship characteristics one is able to calculate the stability characteristics of the vessel for all conditions of loading and thereby determine whether the vessel satisfies the applicable stability criteria. Accurate results from a stability test may in some cases determine the future survival of the vessel and its crew, so the accuracy with which the test is conducted cannot be overemphasized. The condition of the vessel and the environment during the test is rarely ideal and consequently, the stability test is infrequently conducted exactly as planned. If the vessel is not 100 % complete and the weather is not perfect, there ends up being water or shipyard trash in a tank that was supposed to be clean and dry and so forth, then the person in charge must make immediate decisions as to the acceptability of variances from the plan. A complete understanding of the principles behind the stability test and a knowledge of the factors that affect the results is necessary.
SCOPE
1.1 This guide covers the determination of a vessel's light ship characteristics. In this standard, a vessel is a traditional hull-formed vessel. The stability test can be considered to be two separate tasks; the lightweight survey and the inclining experiment. The stability test is required for most vessels upon their completion and after major conversions. It is normally conducted inshore in calm weather conditions and usually requires the vessel be taken out of service to prepare for and conduct the stability test. The three light ship characteristics determined from the stability test for conventional (symmetrical) ships are displacement (“displ”), longitudinal center of gravity (“LCG”), and the vertical center of gravity (“KG”). The transverse center of gravity (“TCG”) may also be determined for mobile offshore drilling units (MODUs) and other vessels which are asymmetrical about the centerline or whose internal arrangement or outfitting is such that an inherent list may develop from off-center weight. Because of their nature, other special considerations not specifically addressed in this guide may be necessary for some MODUs. This standard is not applicable to vessels such as a tension-leg platforms, semi-submersibles, rigid hull inflatable boats, and so on.  
1.2 The limitations of 1 % trim or 4 % heel and so on apply if one is using the traditional pre-defined hydrostatic characteristics. This is due to the drastic change of waterplane area. If one is calculating hydrostatic characteristics at each move, such as utilizing a computer program, then the limitations are not applicable.  
1.3 The values stated in inch-pound units are to be regarded as standard. No other units of measurement are included in this standard.  
1.4 This standard does not purport to address the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

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Publication Date
30-Sep-2013
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ASTM F1321-13e1 - 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
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Contact ASTM International (www.astm.org) for the latest information
´1
Designation: F1321 − 13 AnAmerican National Standard
Standard Guide for
Conducting a Stability Test (Lightweight Survey and
Inclining Experiment) to Determine the Light Ship
1
Displacement and Centers of Gravity of a Vessel
This standard is issued under the fixed designation F1321; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the Department of Defense.
1
ε NOTE—Editorially revised the standard from reviewer comments in October 2013.
INTRODUCTION
This guide provides the marine industry with a basic understanding of the various aspects of a
stability test. It contains procedures for conducting a stability test to ensure that valid results are
obtained with maximum precision at a minimal cost to owners, shipyards, and the government. This
guide is not intended to instruct a person in the actual calculation of the light ship displacement and
centersofgravity,butrathertobeaguidetothenecessaryprocedurestobefollowedtogatheraccurate
dataforuseinthecalculationofthelightshipcharacteristics.Acompleteunderstandingofthecorrect
procedures used to perform a stability test is imperative to ensure that the test is conducted properly
and so that results can be examined for accuracy as the inclining experiment is conducted. It is
recommended that these procedures be used on all vessels and marine craft.
1. Scope applicable to vessels such as a tension-leg platforms, semi-
submersibles, rigid hull inflatable boats, and so on.
1.1 This guide covers the determination of a vessel’s light
ship characteristics. In this standard, a vessel is a traditional 1.2 The limitations of 1 % trim or 4 % heel and so on apply
hull-formed vessel. The stability test can be considered to be if one is using the traditional pre-defined hydrostatic charac-
two separate tasks; the lightweight survey and the inclining teristics.Thisisduetothedrasticchangeofwaterplanearea.If
experiment.The stability test is required for most vessels upon one is calculating hydrostatic characteristics at each move,
their completion and after major conversions. It is normally such as utilizing a computer program, then the limitations are
conducted inshore in calm weather conditions and usually not applicable.
requires the vessel be taken out of service to prepare for and
1.3 The values stated in inch-pound units are to be regarded
conduct the stability test. The three light ship characteristics
asstandard.Nootherunitsofmeasurementareincludedinthis
determined from the stability test for conventional (symmetri-
standard.
cal) ships are displacement (“displ”), longitudinal center of
1.4 This standard does not purport to address the safety
gravity(“LCG”),andtheverticalcenterofgravity(“KG”).The
concerns, if any, associated with its use. It is the responsibility
transverse center of gravity (“TCG”) may also be determined
of the user of this standard to establish appropriate safety and
for mobile offshore drilling units (MODUs) and other vessels
health practices and determine the applicability of regulatory
which are asymmetrical about the centerline or whose internal
limitations prior to use.
arrangement or outfitting is such that an inherent list may
develop from off-center weight. Because of their nature, other
2. Referenced Documents
special considerations not specifically addressed in this guide
2.1 ASTM Standards:
may be necessary for some MODUs. This standard is not
E100Specification for ASTM Hydrometers
3. Terminology
1
This guide is under the jurisdiction of ASTM Committee F25 on Ships and
Marine Technology and is the direct responsibility of Subcommittee F25.01 on
3.1 Definitions:
Structures.
3.1.1 inclining experiment—involves moving a series of
Current edition approved Oct. 1, 2013. Published October 2013. Originally
weights, in the transverse direction, and then measuring the
approved in 1990. Last previous edition approved in 2008 as F1321–92 (2008).
DOI: 10.1520/F1321-13. resultingchangeintheequilibriumheelangleofthevessel.By
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
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F1321 − 13
using this information and applying basic naval architecture
principles, the vessel’s vertical center of gravity KG is deter-
mined.
3.1.2 Condition 1—vessel in Condition 1 is a vessel com-
plete in all respects, but without consumables, stores, cargo,
crew and effects, and without any liquids on board except
machinery fluids, such as lubricants and hydraulics, are at
operating levels. Condition 1
...

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