Section 1

Question 1

UT

Answer 1

Universal Time (new term for Greenwich Mean Time)

Question 2

GMT

Answer 2

Greenwich Mean Time -> UT

Question 3

UTC

Answer 3

Universal Time Coordinate, based on atomic clock

Question 4

LMT

Answer 4

Local Mean Time
- time on navigator’s watch
- is normally set to the time where the vessel is sailing

Question 5

Deck watch chronometer

Answer 5

accurate time piece set to UTC
used for astro navigation

Question 6

why a navigator need the accurate time and date? and from where?

Answer 6

to facilitate the taking of sextant sights.
from Greenwich 000* longitude

Question 7

Is DST applied to UT for astro navigation?

Answer 7

no

Question 8

Difference UT and UTC?

Answer 8

UTC is based on atomic clocks and does not take account of the worlds rotation slowing down.
UT is based on the yearly average of the time passes over the greenwich meridian.

Question 9

Time Zones:
- How many?
- One Time Zone has how much Degrees?

Answer 9

• 12 W and 12 E
• 15°

Question 10

15° =

Answer 10

15* = 1hr

Question 11

1° =

Answer 11

1* = 4min

Question 12

What is the celestial sphere?

Answer 12

A imaginary sphere with the sun, stars and planets painted on it

Question 13

GHA

Answer 13

Greenwich Hour Angle

Question 14

GHA is measured …

Answer 14

…west of Greenwich all the way round to Greenwich again, 360°.

Question 15

Whats the GHA of 45°E?

Answer 15

GHA 315°

Question 16

Whats the “chosen position”?

Answer 16

Its the position for using astro navigation.
It is as close as possible to the estimated position of the vessel but rounded to the nearest whole degree of latitude.

Question 17

LHA

Answer 17

Local Hour Angle

Question 18

LHA is the …

Answer 18

… angle in a clockwise direction from the chosen position to the celestial object (Sun, Moon…)

Question 19

formula
LHA =
LHA =

Answer 19

LHA = GHA - longitude west
LHA = GHA + longitude east

Question 20

The GHA is the angle…

Answer 20

…west from the Prime Meridian to the Geographic Position (GP) of the celestial body.

Question 21

The LHA is the angle …

Answer 21

… west from the Observer to the Geographic Position (GP) of the celestial body.

Question 22

GP

Answer 22

Geographic Position

Question 23

What are Arc to time tables used?

Answer 23

To convert a longitude to its equivalent in time.

Question 24

Can you protect yourself against lightning strike?

Answer 24

• Prevent the sinking by installing a lightning protection. The rigging, the mast, the shrouds are all connected to the keel bolt via little spark distance. spark distance is importent because it prevents galvanic corrosion.

Question 25

Why it is important to have a correct deviation table for your compass?

Answer 25

In case of a lightning the compass will have a deviation.

Question 26

What is a Sextant?

Answer 26

A angle measuring device.

Question 27

Answer 27

Question 28

Two ways to shoot with a Sextant

Answer 28

Way 1: 1. Set Sextant at 0° 2. Set index and horizon shades 3. Look at object 4. hold the index arm and tilt the handle to take the object down to the horizon Way 2: 1. Estimate object Ho 2. Set index shades 3. Look at horizon 4. Move index arm to and fro until object is on horizon.

Question 29

Answer 29

A = Horizon shades B = Horizon mirror C = Index shades D = Index mirror E = Telescope F = Index bar G = Arc H = Magnifying glass I = Clamp J = Micrometer

Question 30

Whats the Global Position?

Answer 30

If a line were taken from the centre of our world through the surface to a celestial object, the point at which it intercepted the surface of the globe, would be the global position of the celestial object.

Question 31

Whats the Zenith?

Answer 31

If a line were taken from the centre of our world through the position of the observer and out into space this would be the zenith.

Question 32

Whats the Zenith distance?

Answer 32

The distance from the observer to the GP of the celestial object in degrees, minutes and seconds.

Question 33

Sextant Check 1: P...

Answer 33

Perpendicularity -> Index Mirror incorrect 1. Take off Telescope 2. Set arm at ~20° 3. Look past index mirror towards 0° (as sun would) 4. Adjust screw to get it perpendicular

Question 34

Rechtwinklig / im Lot

Answer 34

perpendicular

Question 35

Sextant Check 2: S...

Answer 35

Side Error Horizon mirror not correct 1. Set sextant at 0° 0' 2. Look at star 3. adjust screw furthest away from frame on horizon mirror 4. Get stars on top of each other

Question 36

Sextant Check 3: I....

Answer 36

Index Error Mirror not parallel 1. Set sextant at 0° 0' 2. Look at star 3. adjust screw closest to frame on horizon mirror 4. Go back to Check 2: Side Error

Question 37

Sextant Check: Goals

Answer 37

- Perpendicularity: 0 - Side Error: 0 - Some Index Error is okay Note it or make a extra line on the drum at the new "0"

Question 38

Shooting the sun: When do you know its to late ?

Answer 38

The altitude of the Sun will increase with each sight until it is directly overhead. If the altitude is decreasing when you start taking your sights you are too late.

Question 39

When to start shooting the sun?

Answer 39

10 minutes before the expected noon. The altitude of the sun will increase with each sight and then start to decrease as noon passes.

Question 40

Whats Mer.Pass?

Answer 40

It’s the moment when a celestial body (usually the Sun) crosses your local meridian — meaning it's at its highest point in the sky for the day, directly due north or south, depending on your hemisphere.

Question 41

What means "local noon"?

Answer 41

The actual time the sun passes overhead. The local noon of Greenwich can be found in the Almanac.

Question 42

What do we need for a sun sight?

Answer 42

accurate deck watch chronometer set to UT and the time of the meridian passage from the Almanac

Question 43

When do you know you are to late to shoot the sun?

Answer 43

When the altitude is decreasing when you start taking your sights.

Question 44

Whats the Zenith?

Answer 44

A line from the centre of the earth through an object (my boat) into the space

Question 45

? - ? = ZD

Answer 45

90° - Ho = ZD