NAV 1 (Lec)

Question 1

is a type of SONAR (Sound Navigation And Ranging) device used to determine the depth of water by transmitting sound pulses into water.

Answer 1

Echo sounder

Question 2

SONAR

Answer 2

Sound Navigation And Ranging

Question 3

UKC

Answer 3

Under-Keel Clearance

Question 4

is the vertical distance between the lowest part of the ship’s hull and the seabed.

Answer 4

Under-Keel Clearance (UKC)

Question 5

Creation of sound waves can be done by two methods:

Answer 5

1. Magnetostriction
2. Electrostriction

Question 6

The echo sounder uses the formula

Answer 6

distance= speed x time/2

Question 7

The echo sounder system comprises four components:

Answer 7

Transducer, Pulse generator, Amplifier, and Recorder

Question 8

the speed of sound in water is known

Answer 8

1,500 meters per second

Question 9

Here the depth is displayed digitally (in figures) in metres.

Answer 9

Digital display

Question 10

With a _____________ a mark is burned on a roll of paper indicating the depth at regular intervals. With this display a chart of the bottom is produced.

Answer 10

Paper recorder

Question 11

With this display a similar picture is produced as that of the paper recorder. One can either have it in monochrome (shades of one colour) or in full colour. The colour option allows the operator to determine the nature of the bottom

Answer 11

Video display

Question 12

DBS

Answer 12

Draft below the surface

Question 13

Echo Graph

Answer 13

• Range (Phase) Switch
• Sensors
• Stylus Conducting Rail
• Signal From Receiver
• Paper
• Echo line
• Stylus
• Actuator
• Zero line

Question 14

He discovered the technique of echo sounding which turned out to be inefficient in spotting icebergs, but a great tool to measure the depth of the sea.

Answer 14

Alexander Behm

Question 15

Behm had his invention patented in

Answer 15

1913

Question 16

is a device that measures depth of water by measuring the time intervals between pulses of acoustic sound propagation that travel to the bottom of the sea

Answer 16

Echo sounder

Question 17

a typical echo sounder ranges from

Answer 17

0-100 meters

Question 18

The sonic pulses are emitted from a _________ of the instrument.

Answer 18

Transducer

Question 19

is defined as the art of establishing a geographic position on the open sea by use of geological features of the ocean floor.

Answer 19

Bathymetric navigation

Question 20

Bathymetric system consists of two basic components- the _____________.

Answer 20

Transducer and the recorder.

Question 21

is located at or near the keel, and contains both a projector for transmission of a sound signal into the water and a hydrophone for the reception of the returning echoes.

Answer 21

Transducer

Question 22

is located usually in the chart room.

Answer 22

Recorder

Question 23

Most newer models of echo sounders allow the operator to display the depths thus measured in __________________.

Answer 23

Feet, Fathoms, and Meters

Question 24

to generate the sound vibrations and also receive the reflected sound vibration

Answer 24

Transducer

Question 25

to produce electrical oscillations for the transmitting transducer

Answer 25

Pulse generator

Question 26

to amplify the weak electrical oscillations that has been generated by the receiving transducer on reception of the reflected sound vibration

Answer 26

Amplifier

Question 27

for measuring and indicating depth.

Answer 27

Recorder

Question 28

CONTROLS of an echo sounder

Answer 28

• Range switch
• Unit selector switch
• Gain switch
• Paper speed control
• Zero Adjustment or Draught setting control
• Fix or event marker
• Transducer changeover switch
• Dimmer

Question 29

The acoustic pulses of very short duration are transmitted vertically at the rate of ______________ per minute having a beam width of _____________.

Answer 29

5 to 600 pulses

A beam of 12° to 25°

Question 30

Principles used in the working of an Echo Sounder:

Answer 30

1. Ranging
2. Phasing

Question 31

is the subsea element (sonar transponder) of the echo sounder

Answer 31

Transducer

Question 32

detects the radio waves from the transmitter and any waves that have bounced, or reflected off nearby surfaces. This is usually found in chart rooms.

Answer 32

Receivers

Question 33

The velocity of sound in water is taken as

Answer 33

1,500 m/s

Question 34

There are two types of echo sounder:

Answer 34

1. chart recording echo sounder
2. electronic echo sounder

Question 35

Errors of echo sounder

Answer 35

• The velocity of propagation in water
• Stylus speed error
• Multipath Echoes
• Pythagoras error
• Thermal and Density Layer
• Zerro Adjustment error

Question 36

An equipment used to generate and transmit electromagnetic waves carrying messages or signals.

Answer 36

Transmitter

Question 37

The process of converting one form of energy to another is known as

Answer 37

Transduction

Question 38

-is a device that measures depth of water by measuring the time intervals between pulses of acoustic sound propagation that travel to the bottom of the sea. The acoustic sound must be different from that of water

Answer 38

Echo sounding

Question 39

is the bodily sinkage of a ship in the water when making headway it varies from ship to ship.

Answer 39

Squat

Question 40

is the draft when the vessel is not making way or subject to sea, and swell influences, i.e., the maximum draft the ship has loaded to.

Answer 40

Static draft

Question 41

is the draft when the vessel is making way and subject to squat, sea and swell state and increase of draft due to heel when turning.

Answer 41

Dynamic draft

Question 42

UKC is a percentage of the

Answer 42

Static draft