Test 2

Question 1

How do radars operate in relative motion?

Answer 1

Own ship is shown as a fixed point and everything is relative to your own ship

Question 2

What do you use to determine if a close quarters situation is developing?

Answer 2

Proximity and time

Question 3

What info does gps give you?

Answer 3

Continuous positioning and timing info, anywhere in the world under any weather conditions

Question 4

How many satellites are required for a fix?

Answer 4

4

Constellation of 24 operational satellites

Question 5

GPS is operated by the government, so

Answer 5

It can be suspended

Question 6

What contributes to gps error?

Answer 6

Errors originating at satellites, receiver, and signal propagation (atmospheric refraction)

Question 7

Ephemeris error

Answer 7

Difference between expected and actual orbit of a FPS satellite

Question 8

Receiver errors

Answer 8

Clock errors, multi path error, receiver noise, and antenna phase variations

Question 9

Signal propagation errors

Answer 9

Delays of gps signal as it passes through the ionosphere and tropospheric layers

Question 10

ARPA provides range and bearing

Answer 10

Immediately

Question 11

ARPA provides relative motion with 95% accuracy and cpa/tcpa within

Answer 11

1 minute

Question 12

ARPA provides true motion with 95% accuracy and true course and speed within

Answer 12

3 minutes

Question 13

According to cfr 33, required accuracy of ARPA is

Answer 13

. 5 miles

Question 14

Relative vectors give you

Answer 14

Instant assessment of collision risk

Question 15

True vectors give you

Answer 15

Representation of aspect and which rules apply

Question 16

Parallel indexing is

Answer 16

Used as a measure to monitor progress of a vessel on track line, minimize cross track difference, and keep safe distance to shore

Question 17

Benefits of ECDIS

Answer 17

Reduced workload
Displays ships position in real time
Central role at steering station
Situation dependent display

Question 18

ECDIS benefits continued

Answer 18

Radar overlay
Auto route monitoring 
Auto track control
Assistance in special maneuvers 
Up to date info

Question 19

ECDIS risks

Answer 19

System characteristics 
Hardware failure 
System reliability 
Error free software 
Inaccurate chart data
Incorrect position determination 
Over-reliance 
Improper settings
User related short comings

Question 20

LT Cortesia

Answer 20

Grounded on varne bank in English Channel in 2008 because insufficient knowledge of ECDIS
Maladjustment of safety contours
Defaulted to 30 meters

Question 21

CSL Thames

Answer 21

Grounded in sound of mull 2011
3rd mate altered course for another vessel and went to shallow water
Alarm was inoperative 
Incorrect safety contour of 10m
Draft was 10.63m

Question 22

Is ECDIS required by rule 5?

Answer 22

No, because you have other means

Question 23

Safety depth

Answer 23

Ships draft plus squat

Question 24

Safety contour

Answer 24

Division between safe and unsafe water

Draft + squat + UKC - ht of tide

Question 25

Deep contour

Answer 25

Area where depth is such that own ship may experience squat | Twice draft

Question 26

Shallow contour

Answer 26

Highlight gradient of seabed adjacent to safety contour | Next shallower than safety contour

Question 27

Two leading causes of ECDIS incidents

Answer 27

Operator error | Lack of training

Question 28

Effeyrange of AIS

Answer 28

20 miles

Question 29

What static AIS info?

Answer 29

``` Every 6 minutes: IMO # Name and call sign Length and beam Ship type Demensions Location of fixing antenna Type of positioning equipment Destination ETA ```

Question 30

What dynamic AIS info?

Answer 30

``` 2-10 seconds: MMSI nav status Rate of turn Position coordinates Course over ground Heading Bearing at own position UTC seconds ```

Question 31

Advantages of AIS

Answer 31

Longer range detection Real time computation No risk of target swap No target loss in clutter

Question 32

Disadvantages of AIS

Answer 32

Complacency Accuracy is only as good as what was inputed Not all ships have

Question 33

Radar most accurate determination

Answer 33

Bearing

Question 34

What is dilution of precession?

Answer 34

Happens when gps satellites are close together Best when one overhead and others equally spaced across the horizon Higher dilution equals more position error

Question 35

What is target swap?

Answer 35

Multiple vessels close proximity to each other and same bearing from own vessel

Question 36

Identity and explain the basic theory of gps

Answer 36

1) . Space segment consists of satellites that transmit radio signal at speed of light which contain a navigation message (location and time) 2) . User segment consists of receiver which receives space segment transmission. Transmission is processed and position of receiver is calculated. 3) . User segment does not transmit a signal 4) . Control segment of god system consists of worldwide network of tracking stations, with a master control station in Colorado Springs. Tracks satellites to determine locations. 5) . 4 satellites must be visible to provide info

Question 37

Explain dgps operation

Answer 37

1) . Supplements and/or enhances gps 2) . Reference stations provide corrections to gps signals 3) . Each ref station has a gps receiving system and gps position of reference station is computed and compared to its actual position 4) . The differential info or error in fix position is transmitted to receivers used in the geographical area near the ref station 5) . Dgps optimum range of 150 miles

Question 38

Describe operation of AIS

Answer 38

1) . Continuously transmits and receive info on maritime vhf (25 or 12.5 kHz) 2) . Transmissions fit into a time slot and stations synchronize themselves to other stations to avoid overlap of slot transmissions 3) . Range is line of sight 4) . Transmits static, dynamic, and voyage info 5) . Changes in heading and course are immediately apparent

Question 39

Why is parallel indexing used

Answer 39

1). Measure to monitor progress of a vessel on the track and minimize cross track distance 2). Bearing line drawn parallel to original course with a known fixed perpendicular distance between both the lines is used as a reference 3). Increase or decrease of perpendicular distance between the bearing lines drawn parallel to course line and ships position any time will indicate cross track deviation Parallel indexing is frequently used in areas where coastlines are rocky and provide strong Radar returns