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Flashcards in Test 2 Deck (39)
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1

How do radars operate in relative motion?

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

2

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

Proximity and time

3

What info does gps give you?

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

4

How many satellites are required for a fix?

4
Constellation of 24 operational satellites

5

GPS is operated by the government, so

It can be suspended

6

What contributes to gps error?

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

7

Ephemeris error

Difference between expected and actual orbit of a FPS satellite

8

Receiver errors

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

9

Signal propagation errors

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

10

ARPA provides range and bearing

Immediately

11

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

1 minute

12

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

3 minutes

13

According to cfr 33, required accuracy of ARPA is

. 5 miles

14

Relative vectors give you

Instant assessment of collision risk

15

True vectors give you

Representation of aspect and which rules apply

16

Parallel indexing is

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

17

Benefits of ECDIS

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

18

ECDIS benefits continued

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

19

ECDIS risks

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

20

LT Cortesia

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

21

CSL Thames

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

22

Is ECDIS required by rule 5?

No, because you have other means

23

Safety depth

Ships draft plus squat

24

Safety contour

Division between safe and unsafe water
Draft + squat + UKC - ht of tide

25

Deep contour

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

26

Shallow contour

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

27

Two leading causes of ECDIS incidents

Operator error
Lack of training

28

Effeyrange of AIS

20 miles

29

What static AIS info?

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

30

What dynamic AIS info?

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