ASTM D6318-24
(Practice)Standard Practice for Calibrating a Fathometer Using a Bar Check Method
Standard Practice for Calibrating a Fathometer Using a Bar Check Method
SIGNIFICANCE AND USE
4.1 The accuracy of depth measurements made by a fathometer or echo sounder requires a number of corrections because of the variability of sound or acoustic velocity in water with changes in temperature, salinity, and depth of water. In addition instability of the equipment can also result in significant errors. For additional information see Practice D5073.
4.2 Calibration of echo sounding instruments is absolutely critical in assuring the adequacy of depth measurements. When an echo sounder has been accurately calibrated, any observed (recorded) depth can be related to the true depth of water. Since the intended purpose of echo sounding is to measure the “true” depth, an independent “true” reference must be used.
4.3 A bar-check is the most wide-spread, easiest to construct, and most economical mechanical method to determine corrections for instrument and velocity errors.
4.4 This procedure explains the calibration of a fathometer or electronic depth sounder using a bar-check.
4.5 Bar-checking techniques and equipment are general in nature and may need to be modified for use in specific field conditions.
SCOPE
1.1 This practice provides the user with procedures used in manually calibrating the fathometer or electronic depth sounder. This narrative describes calibration terminology, describes acceptable environmental conditions for calibration, and describes the calibration procedures.
1.2 The references cited contain useful information in the construction and the correct operation of the calibration equipment.
1.3 Any references cited in this narrative to specific products or brand names are made for information only, and is intended to be descriptive, but not restrictive, of products that will perform satisfactorily.
1.4 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard.
1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.
1.6 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
General Information
Relations
Standards Content (Sample)
This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: D6318 − 24
Standard Practice for
1
Calibrating a Fathometer Using a Bar Check Method
This standard is issued under the fixed designation D6318; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope D5073 Practice for Depth Measurement of Surface Water
1.1 This practice provides the user with procedures used in
3. Terminology
manually calibrating the fathometer or electronic depth
sounder. This narrative describes calibration terminology, de-
3.1 Definitions—Refer to Terminology D1129 for terms
scribes acceptable environmental conditions for calibration, used in this guide.
and describes the calibration procedures.
3.2 Definitions of Terms Specific to This Standard:
1.2 The references cited contain useful information in the 3.2.1 bar, n—a section of metallic channel, I-beam, T-beam,
construction and the correct operation of the calibration equip- pipe, plate, or ball that will reflect sound waves produced by a
ment. fathometer.
3.2.2 bar-check, n—a method for calibrating a fathometer
1.3 Any references cited in this narrative to specific prod-
by setting a sound or accoustic reflector (bar) below a survey
ucts or brand names are made for information only, and is
vessel to a known depth below a sounding transducer.
intended to be descriptive, but not restrictive, of products that
will perform satisfactorily.
3.2.3 draft (transducer draft), n—the vertical distance from
the bottom of the transducer to the surface of the water.
1.4 The values stated in inch-pound units are to be regarded
as standard. The values given in parentheses are mathematical
3.2.4 fathometer, n—An electronic device for registering
conversions to SI units that are provided for information only
depths of water by measuring the time required for the
and are not considered standard.
transmission and reflection of sound waves between a sonic
transducer and the lake or river bottom.
1.5 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
3.2.5 sound, n—to determine the depth of water.
responsibility of the user of this standard to establish appro-
3.2.6 sounding scroll, n—the chart record of an underwater
priate safety, health, and environmental practices and deter-
cross section or profile of the bottom.
mine the applicability of regulatory limitations prior to use.
3.2.7 transducer, n—a device for translating electrical en-
1.6 This international standard was developed in accor-
ergy to acoustical energy and acoustical energy back to
dance with internationally recognized principles on standard-
electrical energy.
ization established in the Decision on Principles for the
Development of International Standards, Guides and Recom-
4. Significance and Use
mendations issued by the World Trade Organization Technical
4.1 The accuracy of depth measurements made by a fath-
Barriers to Trade (TBT) Committee.
ometer or echo sounder requires a number of corrections
2. Referenced Documents
because of the variability of sound or acoustic velocity in water
2
with changes in temperature, salinity, and depth of water. In
2.1 ASTM Standards:
addition instability of the equipment can also result in signifi-
D1129 Terminology Relating to Water
cant errors. For additional information see Practice D5073.
4.2 Calibration of echo sounding instruments is absolutely
1
This practice is under the jurisdiction of ASTM Committee D19 on Water and
critical in assuring the adequacy of depth measurements. When
is the direct responsibility of Subcommittee D19.07 on Sediments, Geomorphology,
an echo sounder has been accurately calibrated, any observed
and Open-Channel Flow.
Current edition approved April 1, 2024. Published April 2024. Originally
(recorded) depth can be related to the true depth of water. Since
approved in 1998. Last previous edition approved in 2014 as D6318 – 03 (2014)
the intended purpose of echo sounding is to measure the “true”
which was withdrawn July 2023 and reinstated in April 2024. DOI: 10.1520/D6318-
depth, an independent “true” reference must be used.
24.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
4.3 A bar-check is the most wide-spread, easiest to
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
construct, and most economical mechanical method to deter-
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. mine corrections
...
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