Hydrographic Surveying: Sounding Equipment
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1
What is one primary purpose of hydrographic surveying?
To depict the bathymetry of the seafloor\
2
What is one of the most important operations in hydrographic surveying?
Depth determination\
3
What is the main learning outcome of Lesson 4.1?
Identifying the suitable sounding method or equipment based on the project's purpose and area\
4
What is the determination of the bed profile of a water body?
Sounding\
5
What is the measurement of the depth of the bed below the water surface?
Sounding\
6
What are the two main categories of sounding methods?
Direct methods and indirect methods\
7
What are the three direct sounding methods?
Sounding rods or poles, leadline, and sounding machine\
8
What are sounding rods generally graduated in?
Meters, decimeters, and half-decimeters\
9
In what direction are the graduations of sounding rods arranged?
From the bottom upwards\
10
What does the sounding rod reading at the water surface directly indicate?
The depth of water\
11
What is fitted at the bottom of a sounding rod to maintain its verticality?
An arrow or lead shoe\
12
What is the purpose of the arrow or lead shoe on a sounding rod?
To maintain the rod's verticality during sounding\
13
What should be the base area of the arrow or lead shoe?
Large enough to prevent it from sinking into the mud at the bed\
14
Where is the use of sounding rods not advisable?
Areas with strong currents\
15
Why are sounding rods unsuitable for areas with strong currents?
It is difficult to maintain the rod's verticality, resulting in incorrect measurements\
16
What is another name for a sounding line?
Leadline\
17
What is a leadline made of?
A thin rope with a plummet attached at its end\
18
What is the most common material used for a leadline plummet?
Lead\
19
Why is it called a leadline regardless of the plummet's composition?
Because lead is the most common material used for the plummet\
20
What is considered the most primitive tool in depth measurement?
Leadline\
21
Who manually casts or swings the leadline into the water?
The leadsman\
22
At what intervals is a leadline graduated?
Every meter\
23
What materials are used for leadline graduation tags?
Cloth or leather\
24
Where are leadlines unsuitable for taking soundings?
Areas with swift-flowing water or strong currents\
25
Why does a leadline give a greater measured length than the true depth in deep, swift-flowing water?
Because of drag\
26
What correction is required when drag affects a leadline measurement?
A correction to the measured length to obtain the correct depth\
27
What is a sounding machine?
An improved version of the leadline method\
28
What are the main components of a sounding machine?
A rotatable barrel, flexible wire, and lead weight\
29
How can the barrel of a sounding machine be rotated?
Automatically or manually\
30
What is attached to one end of the flexible wire in a sounding machine?
A lead weight\
31
What mechanism raises or lowers the weight of a sounding machine?
The winding handle\
32
When is a sounding machine particularly useful?
When taking a large number of soundings\
33
Up to what water depth is a sounding machine useful?
30 meters\
34
What are the two main categories of sounding methods?
Direct and indirect methods\
35
What techniques are commonly used in indirect depth determination?
Acoustic techniques\
36
What device is used in acoustic depth determination?
Transducer\
37
What does a transducer convert into high-frequency sound?
Electrical energy from the transmitter\
38
What does SONAR stand for?
Sound Navigation and Ranging\
39
What is the most common equipment used in indirect sounding?
Echosounder\
40
What are the two main units of an echosounder?
Transmitting unit and receiving unit\
41
What does the transmitter of an echosounder emit?
Underwater supersonic pulses\
42
What activates the receiver of an echosounder?
The echoes of reflected pulses from the river or sea bed\
43
What are the three types of echosounders discussed in Lesson 4.1?
Single Beam Echosounder (SBES), Multi-beam Echosounder (MBES), and Multichannel Echosounder (MCES)\
44
What is another name for a Single Beam Echosounder (SBES)?
Fathometer\
45
How does a Single Beam Echosounder determine water depth?
By measuring the time interval between the emitted sound and its returning echo\
46
What is the sonar pulse emitted by an SBES commonly called?
Ping\
47
Where is the transducer of an SBES positioned?
Just below the water surface\
48
What does ensonifying mean?
Filling an area with sound\
49
What type of area does an SBES ensonify beneath the boat?
A small area\
50
What type of transducer does a Multi-beam Echosounder (MBES) have?
A wide angular lateral aperture transducer\
51
What does an MBES map on the seafloor?
A contiguous area of the bottom\
52
In what direction does an MBES usually map a strip of points?
Perpendicular to the path of the survey vessel\
53
What provides broader coverage in an MBES survey?
Successive pings during one vessel traverse\
54
What problem of earlier sounding methods does MBES reduce or eliminate?
Gaps in coverage\
55
What is the full name of MCES?
Multichannel Echosounder\
56
What type of system does an MCES use to map the seafloor?
A sweep system\
57
What type of water bodies is an MCES specifically designed for?
Canals, rivers, and other shallow bodies of water\
58
What does an MCES provide through its depth and bottom detection capabilities?
Detailed bottom imagery
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