1 Flashcards by Ryan Kinser

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

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

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How should clocks be changed to maintain timezones?

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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The date is the same all over the world at

1200 GMT

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Reference point to determine GMT is mean sun over

180* longitude

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Universal time (UT1) is

Greenwich mean time

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Measurement of local time is based on Sun over

Lower branch of observers meridian

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3 REASONS Mean sun is used as reference for solar time

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

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NOT a reason why sun is used for solar time

Measurement of time is along equator

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Daylight savings time adopts

One zone to the east

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Apparent time

Visible sun moving along the ecliptic

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Difference between mean and apparent time

Apprx 16 minutes

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Primary use of apparent time

Determine time of meridian transit

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

Equation of time

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The equation of time measures

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

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

Time of local apparent noon

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Local sidereal time =

LHA of Aries

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Sidereal time is NOT used

In sight reduction of planet observations

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Sidereal day begins

First point of Aries is over upper branch of reference meridian

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Sidereal day apprx how much shorter than solar day?

4 minutes

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

Use of different reference points

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

Vernal equinox

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Length of year w respect to vernal equinox

Tropical year

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Tropical year differs from which year by 20 minutes?

Sidereal year.

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Lunar day is known as

Tidal day

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Lunar day

Longer than solar day

Lunar day

24h 50m 00s

Time diagram observed from above

South celestial pole

Time diagram on plane of

Celestial equator

At meridian transit, diagram to illustrate angles involved based on

Plane of observers meridian

D005NG

Date is one day later than GMT In East longitude Sun has already passed the lower branch of observers meridian

D008NG

Represents morning Sun sight Meridian angle of Sun is east

First point of Aries: Sun is at

0* declination going to northerly declinations

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

March 21

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

23*27'

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

Increased obliquity of celestial sphere/ Sun's diurnal circle

Greater pressure diff between high and low pressure center

Greater force of wind

Cumulonimbus most likely accompany

Cold front

Which symbol in D018NG represents occluded front?

Which symbol in D018NG represents warm front?

Warm front - barometric pressure usually

Falls

US ATON system - yellow buoy is

Special purpose mark

Which buoy indicates dredging area?

Yellow

White lights found on what buoys

Information and regulatory

White and orange buoys may show what color light ?

White

NOT true concerning color sector of lights.

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

23 meters =

12.6 fathoms

20 fathom curve symbol

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

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

Estimated position

@ 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?

The set is 270*, drift is 0.25 kt

Apply to Fathometer reading to determine depth

ADD draft

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

Transducer

All echo sounders can measure

Actual depth of water below keel

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

Multiple echoes

Racon buoy in D017NG on PPI

Condition indicates that radar needs maintenance

Serrated range rings

Spring tide occurs

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

Diff between heights of low and high tide

Range

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

West wind drift

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

Pilot Chart

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

Kuroshio Current

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

Become weak and variable

Info about currents on Pacific Coast of US

Tidal Current Tables

Daylight savings time - to adjust tide and current calcs

Add one hour to the times listed for the reference stations

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

Estimated position

Centerline of channel marked on bridge with LATERAL system

Red and white octagon

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

3 hours after flood begins

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

Weather maps an local knowledge

Weather observations provided by each weather station DOES NOT include

Predicted weather for the next 12 hours

Pressure sensitive element of aneroid barometer

Sylphon cell

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

Hail

Low, dark, sheetlike cloud associated w continuous precipitation

Nimbostratus

Weather front

Air masses of diff temps meet

Northern Hemi - high pressure due west - what winds?

North to west

Weather conditions in low pressure system

Precipitation and cloudiness

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

A tropical cyclone south of your vessel

ECDIS required to display

Depth contours

ECDIS must have capability to preserve the track record of precious

12 hours

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

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