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1 Flashcards

1
Q 
Standard Time Meridians to Zone Descriptions : 
Heading East
15*, 30*, 45*, .... 180*
Heading West
15*, 30*, 45*, .... 180*
A

East :
-1, -2, -3, …. -12
West:
+1, +2, +3, …. +12

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2
Q

How should clocks be changed to maintain timezones?

A

Exactly between meridians DEPENDING ON THE DIRECTION YOU ARE HEADING
730’ E , 2230’ E,…, 17230’ E, 17230’ W,…, 2230’ W, 730’ W,
It continues in either direction

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3
Q

The date is the same all over the world at

A

1200 GMT

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4
Q

Reference point to determine GMT is mean sun over

A

180* longitude

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5
Q

Universal time (UT1) is

A

Greenwich mean time

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6
Q

Measurement of local time is based on Sun over

A

Lower branch of observers meridian

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7
Q

3 REASONS Mean sun is used as reference for solar time

A

Motion of apparent sun is along ecliptic
Speed of earths revolution is not constant
Variations in the earths rotational speed

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8
Q

NOT a reason why sun is used for solar time

A

Measurement of time is along equator

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9
Q

Daylight savings time adopts

A

One zone to the east

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10
Q

Apparent time

A

Visible sun moving along the ecliptic

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11
Q

Difference between mean and apparent time

A

Apprx 16 minutes

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12
Q

Primary use of apparent time

A

Determine time of meridian transit

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13
Q

The difference between local apparent time (LAT) and local mean time (LMT) is indicated by the

A

Equation of time

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14
Q

The equation of time measures

A

Time between passage of the mean sun and the apparent sun over a meridian

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15
Q

When equation of time is taken from Nautical Almanac for use in celestial nav, it determines

A

Time of local apparent noon

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16
Q

Local sidereal time =

A

LHA of Aries

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17
Q

Sidereal time is NOT used

A

In sight reduction of planet observations

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18
Q

Sidereal day begins

A

First point of Aries is over upper branch of reference meridian

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19
Q

Sidereal day apprx how much shorter than solar day?

A

4 minutes

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20
Q

Diff of sidereal day(shorter) to solar day is due to

A

Use of different reference points

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21
Q

Apprx positions of the stars are based on sidereal time, which is based upon rotation of earth relative to

A

Vernal equinox

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22
Q

Length of year w respect to vernal equinox

A

Tropical year

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23
Q

Tropical year differs from which year by 20 minutes?

A

Sidereal year.

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24
Q

Lunar day is known as

A

Tidal day

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25
Q

Lunar day

A

Longer than solar day

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26
Q

Lunar day

A

24h 50m 00s

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27
Q

Time diagram observed from above

A

South celestial pole

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28
Q

Time diagram on plane of

A

Celestial equator

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29
Q

At meridian transit, diagram to illustrate angles involved based on

A

Plane of observers meridian

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30
Q

D005NG

A

Date is one day later than GMT

In East longitude

Sun has already passed the lower branch of observers meridian

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31
Q

D008NG

A

Represents morning Sun sight

Meridian angle of Sun is east

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32
Q

First point of Aries: Sun is at

A

0* declination going to northerly declinations

33
Q

First point of Aries is position of Sun on celestial sphere on or about

A

March 21

34
Q

Plane of ecliptic is inclined to plane of celestial equator by what angle?

A

23*27’

35
Q

Change in length of day becomes greater as Lat increases bc of

A

Increased obliquity of celestial sphere/ Sun’s diurnal circle

36
Q

Greater pressure diff between high and low pressure center

A

Greater force of wind

37
Q

Cumulonimbus most likely accompany

A

Cold front

38
Q

Which symbol in D018NG represents occluded front?

A

D

39
Q

Which symbol in D018NG represents warm front?

A

C

40
Q

Warm front - barometric pressure usually

A

Falls

41
Q

US ATON system - yellow buoy is

A

Special purpose mark

42
Q

Which buoy indicates dredging area?

A

Yellow

43
Q

White lights found on what buoys

A

Information and regulatory

44
Q

White and orange buoys may show what color light ?

A

White

45
Q

NOT true concerning color sector of lights.

A

Color sectors are expressed in degrees from the light toward the vessel

46
Q

23 meters =

A

12.6 fathoms

47
Q

20 fathom curve symbol

A

-..-..-..-..-..-

48
Q

Single line of position combined with a dead-reckoning position results in a

A

Estimated position

49
Q

@ 0000, fix position and plot new DR track line. @ 0200 again fix pos. And it is 0.5 miles W of your DR. What is true?

A

The set is 270*, drift is 0.25 kt

50
Q

Apply to Fathometer reading to determine depth

A

ADD draft

51
Q

Modern fathometers - sonic or ultrasonic soun waves are produced electrically by means of

A

Transducer

52
Q

All echo sounders can measure

A

Actual depth of water below keel

53
Q

Ship overtaking you close to stbd. 3 radar targets at 90* relative at ranges of .5 mi, 1 mi, and 1.5 mi. In this case the unwanted echoes are called

A

Multiple echoes

54
Q

Racon buoy in D017NG on PPI

A

B

55
Q

Condition indicates that radar needs maintenance

A

Serrated range rings

56
Q

Spring tide occurs

A

When the Sun, Moon, and Earth are nearly in line, in any order

57
Q

Diff between heights of low and high tide

A

Range

58
Q

The steady current circling the globe at about 60* S is the

A

West wind drift

59
Q

Which would you consult for info about general current circulation in the North Atlantic?

A

Pilot Chart

60
Q

Which ocean current is “warm” based on the Lat in which it originates and the effect it has on the climate?

A

Kuroshio Current

61
Q

When declination of moon is 0*12.5’S, you can expect some tidal currents in Gulf Coast ports to

A

Become weak and variable

62
Q

Info about currents on Pacific Coast of US

A

Tidal Current Tables

63
Q

Daylight savings time - to adjust tide and current calcs

A

Add one hour to the times listed for the reference stations

64
Q

Position obtained by applying est. Current and wind to vessels course and speed

A

Estimated position

65
Q

Centerline of channel marked on bridge with LATERAL system

A

Red and white octagon

66
Q

Wish to use flood tide to facilitate docking stbd side to heading seaward, what time to enter Delaware Bay?

A

3 hours after flood begins

67
Q

Weather info provided by National Weather Service advisories ahould be used along with

A

Weather maps an local knowledge

68
Q

Weather observations provided by each weather station DOES NOT include

A

Predicted weather for the next 12 hours

69
Q

Pressure sensitive element of aneroid barometer

A

Sylphon cell

70
Q

Precipitation only in T-storms w strong convection currents that convey raindrops above and below freezing level is

A

Hail

71
Q

Low, dark, sheetlike cloud associated w continuous precipitation

A

Nimbostratus

72
Q

Weather front

A

Air masses of diff temps meet

73
Q

Northern Hemi - high pressure due west - what winds?

A

North to west

74
Q

Weather conditions in low pressure system

A

Precipitation and cloudiness

75
Q

Presently sunny w steady barometer - low swell approaches from south with crests passing at relatively long periods of about 4/minute. Usually indicates

A

A tropical cyclone south of your vessel

76
Q

ECDIS required to display

A

Depth contours

77
Q

ECDIS must have capability to preserve the track record of precious

A

12 hours

78
Q

Plotting a running fix. LOP to be run forward is an arc from a radar range, which technique should be used?

A

Position of object should be advanced swung using the radius of the old arc

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