ASTM F1321-92(2008)
(Guide)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
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
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. 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.
1.2 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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Designation: F1321 − 92(Reapproved 2008) An American National Standard
Standard Guide for
Conducting a Stability Test (Lightweight Survey and
Inclining Experiment) to Determine the Light Ship
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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.
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 of the user of this standard to establish appropriate safety and
health practices and determine the applicability of regulatory
1.1 This guide covers the determination of a vessel’s light
limitations prior to use.
ship characteristics. The stability test can be considered to be
two separate tasks; the lightweight survey and the inclining
2. Terminology
experiment.The stability test is required for most vessels upon
2.1 Definitions:
their completion and after major conversions. It is normally
2.1.1 inclining experiment—involves moving a series of
conducted inshore in calm weather conditions and usually
known weights, normally in the transverse direction, and then
requires the vessel be taken out of service to prepare for and
measuringtheresultingchangeintheequilibriumheelangleof
conduct the stability test. The three light ship characteristics
the vessel. By using this information and applying basic naval
determined from the stability test for conventional (symmetri-
architecture principles, the vessel’s vertical center of gravity
cal) ships are displacement (“displ”), longitudinal center of
KG is determined.
gravity(“LCG”),andtheverticalcenterofgravity(“KG”).The
2.1.2 light ship—a vessel in the light ship condition (“Con-
transverse center of gravity (“TCG”) may also be determined
dition I”) is a vessel complete in all respects, but without
for mobile offshore drilling units (MODUs) and other vessels
consumables, stores, cargo, crew and effects, and without any
which are asymmetrical about the centerline or whose internal
liquids on board except that machinery fluids, such as lubri-
arrangement or outfitting is such that an inherent list may
cants and hydraulics, are at operating levels.
develop from off-center weight. Because of their nature, other
special considerations not specifically addressed in this guide 2.1.3 lightweight survey—this task involves taking an audit
may be necessary for some MODUs.
ofallitemswhichmustbeadded,deducted,orrelocatedonthe
vessel at the time of the stability test so that the observed
1.2 This standard does not purport to address the safety
condition of the vessel can be adjusted to the light ship
concerns, if any, associated with its use. It is the responsibility
condition. The weight, longitudinal, transverse, and vertical
location of each item must be accurately determined and
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recorded. Using this information, the static waterline of the
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
ship at the time of the stability test as determined from
Structures.
measuring the freeboard or verified draft marks of the vessel,
Current edition approved Nov. 1, 2008. Published December 2008. Originally
thevessel’shydrostaticdata,andtheseawaterdensity;thelight
approved in 1990. Last previous edition approved in 2004 as F1321–92 (2004).
DOI: 10.1520/F1321-92R08. ship displacement and longitudinal center of gravity can be
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
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F1321 − 92 (2008)
obtained. The transverse center of gravity may also be would result from a significant change i
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