Exam 1

Question 1

Doppler speed log

Answer 1

registers a change in frequency between the transmitted signal and the received signal and then calculates the velocity of the vessel based on the frequency shift

Question 2

Echo sounding is a type of?

Answer 2

Sound Navigation and Ranging (SONAR)

Question 3

Echo sounding is used to?

Answer 3

determine the depth of the water by transmitting sound pulses into water

Question 4

Fathometer indicates the depth of water where?

Answer 4

under keel or where the transducer is located

Question 5

Fathometer is dependent on both?

Answer 5

specular (direct) and diffuse (reflection at an angle) reflection

Question 6

Range of fathometer is?

Answer 6

0 to 4,500 feet

Question 7

Fathometers emit how many pulses per minute?

Answer 7

10 to 600 pulses per minute

Question 8

Speed of sound through water is approximately?

Answer 8

4,800 feet per second

Question 9

You should always know your _________s location.

Answer 9

Fathometer

Question 10

What does a Oscillator do?

Answer 10

creates electrical signal at the desired frequency

Question 11

What does a Transducer do?

Answer 11

converts electrical signal into ultrasonic vibrations for transmission. Also converts the return echo back into an electrical signal

Question 12

Name two types of Transducers?

Answer 12

Electrostrictive and Magnetostrictive

types

Question 13

It is essential the user select the _____ depth soundings on the depth sounder as the navigational chart in use.

Answer 13

SAME

Question 14

Gain: the ____ the bottom, the less gain (sensitivity) required

Answer 14

harder

Question 15

Define Bathymetric Navigation?

Answer 15

The method of navigating by using a fathometer

Question 16

Speed Log is used to determine the vessels _____.

Answer 16

Velocity

Question 17

Name three different Speed Logs?

Answer 17

1. Patent logs: Small tubular finned device attached to the end of the drag line that would spin as the vessel moved through the water
2. Pitot-static (pitometerlog): based on principle of comparative measurements between static and dynamic pressured in a pilot tube extending from a vessel’s hull
3. Impeller log: electromagnetic device which used a small propeller spun by water which was then converted to an electrical signal

Question 18

Modern Speed Logs are?

Answer 18

Electromagnetic or doppler

Question 19

Define the Doppler Speed Log, Doppler Effect:

Answer 19

Shift in frequency between a transmitted and received signal caused by the motion of a vessel over bottom or through water

Question 20

The Doppler Speed Log receives what through the water?

Answer 20

reflected signal from particles suspended in water.

Question 21

True or False: The Doppler Speed Log registers change in frequency, not time, to measure speed

Answer 21

True

Question 22

The speed of sound through ocean water is nearly always __________.

Answer 22

faster than the speed of calibration for the fathometer

Question 23

Which factor has the greatest effect on the amount of gain required to obtain a fathometer reading?

Answer 23

Type of bottom

Question 24

If a sound signal is emitted from the oscillator of a fathometer, and two seconds elapse before the returning signal is picked up, what depth of water is indicated?

Answer 24

824 fathoms

Question 25

When operated over a muddy bottom, a fathometer may indicate __________.

Answer 25

two depth readings

Question 26

The recording fathometer produces a graphic record of the __________.

Answer 26

depth underneath the keel against a time base

Question 27

What should you apply to a fathometer reading to determine the depth of water?

Answer 27

Add the draft of the vessel.

Question 28

When using an echo sounder in deep water, it is NOT unusual to __________.

Answer 28

receive a strong return at about 200 fathoms (366 meters) during the day, and one nearer the surface at night

Question 29

All echo-sounders can measure the __________.

Answer 29

actual depth of water below keel

Question 30

The speed of sound in water is approximately __________.

Answer 30

4.5 times its speed in air

Question 31

A Doppler speed log indicates speed over ground __________.

Answer 31

in the bottom return mode

Question 32

A Doppler speed log indicates speed through the water __________.

Answer 32

in the volume reverberation mode

Question 33

What will NOT induce errors into a Doppler sonar log?

Answer 33

Increased draft

Question 34

A Doppler log in the volume reverberation mode indicates __________.

Answer 34

speed through the water

Question 35

A Doppler log in the bottom return mode indicates the __________.

Answer 35

speed over the ground

Question 36

Velocity of sound through water to calculate depth of water?

Answer 36

(Depth = R * T)

Question 37

The assumed speed of sound through water is approximately ______ feet per second or _____ greater than the speed of sound through air

Answer 37

4800, 4.5

Question 38

Radar is an acronym for?

Answer 38

radio detecting and ranging

Question 39

First commercial application on US merchant vessels occurred in the late _____.

Answer 39

1940's

Question 40

Define the Fundamentals of RADAR?

Answer 40

A transceiver sends a pulse modulated signal out, measures the time until the signal’s return, determines distance from this, and can display the returns in a directionally accurate presentation because of the use of a directional antenna

Question 41

Radar waves are emitted on two different frequencies, what are they?

Answer 41

1. X Band operates at 9,375 MHz with a wavelength of 3.2 centimeters 2. S Band operates at 3,070 MHz with a wavelength of 10 centimeters

Question 42

Define Superrefraction?

Answer 42

Superrefraction: increases downward bending of radar waves and therefore increases the ranges at which targets may be detected

Question 43

Define Subrefraction?

Answer 43

Subrefraction: radar waves bend upward, thus the range at which targets can be detected is reduced

Question 44

Define Ducting?

Answer 44

Ducting: extreme cases of superrefraction.

Question 45

Sea Return is minimized by adjusting what?

Answer 45

RF GAIN or SEA CLUTTER CONTROL

Question 46

Name the _____ interferences?

Answer 46

8

Question 47

What are the different Radar interference's?

Answer 47

``` Rain Clutter Indirect or false echoes Multiple Echoes Second-Trace Echoes Side Lobe Effects Electronic Interference Overhead Cable Effect Spoking (Equipment Failure) ```

Question 48

True or False: Spoking is a Equipment Failure, Occurs when there is a modulator problem and indicated by many radial lines showing up on the radar screen

Answer 48

TRUE

Question 49

The Fundamentals of RADAR!!!!!, THREE FACTS:

Answer 49

Uses basic time-rate-distance computations Known speed of radar waves and time it takes for an echo to return Radar waves travel at the speed of light

Question 50

Watch Condition A?

Answer 50

One Deck Officer: Open Waters Clear Visibility

Question 51

Watch Condition B?

Answer 51

Two Deck Officers: Entering or Leaving a Port Without the Pilot onboard

Question 52

Watch Condition C?

Answer 52

Three Deck Officers: Situation where increased navigational assistance is needed, reduced visibility, higher traffic.

Question 53

Watch Condition D?

Answer 53

Local Pilot Embarked

Question 54

RULE 5

Answer 54

Look-Out

Question 55

RULE 6

Answer 55

Safe Speed

Question 56

RULE 7

Answer 56

Risk of Collision

Question 57

Describe a Fathometer?

Answer 57

Determines depth of water by generating sonic pulses that are directed towards the ocean floor The sonic pulses are reflected off the ocean floor and return to the transducer