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First Semester (BSMT) > Magnetic Compass (MIDTERM) > Flashcards

Magnetic Compass (MIDTERM) Flashcards

1
Q

an instrument that uses magnetized steel bar to indicate direction relative to the earth’s magnetic poles

A

magnetic compass`

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2
Q

two (2) basic types of magnetic compass

A

(a) The dry card Compass (b) The wet card Compass

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2
Q

consists of a card with cardinal graduations, suspended inside a bowl. The suspension should provide a frictionless support

A

basic compass (whether dry or wet)

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3
Q

use ring magnet as a directive element

A

Modern compasses

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4
Q

is a cylindrical container made of non-ferrous material that houses the different components of the magnetic compass

A

binnacle

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5
Q

is housed in the top part of the binnacle whereas the middle part is accessible through a door housing the corrector magnets extending to the projector towards the forward

A

compass bowl

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6
Q

Magnetic compass correctors in a binnacle

A
  1. Flinders Bar
  2. Quadrantal Spheres
  3. Heeling Magnet
  4. Athwartship Magnets
  5. Fore and Aft Magnets
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7
Q

is a soft iron corrector vertically placed in the for’d or aft part of the binnacle depending on the extension of the superstructure area abaft of or forward of the binnacle

A

Flinders Bar

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8
Q

are two soft iron spheres fitted in brackets on either side of the binnacle.

A

Quadrantal Correctors

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9
Q

the distance between the –can be altered during adjustent of the compass

A

quadrantal correctors

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10
Q

The — maybe changed during adjustment of the compass

A

length of the bar

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11
Q

is fitted on top of the binnacle and is non-ferrous.

A

helmet

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12
Q

This is in place to protect the compass bowl from the weather and harsh conditions

A

helmet

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13
Q

Magnets are aligned —- to create horizontal magnetic fields to compensate for the permanent horizontal components of the ship’s magnetism

A

fore and aft and athwartships

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14
Q

compensate for the induced magnetism caused by the effect the earth’s magnetic field has on the ship’s magnetism

A

Soft iron correcting spheres or plates and the Flinders bar

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14
Q

compensate for the vertical component of the ship’s magnetism

A

Heeling error magnets

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15
Q

is sensitive to rolling and pitching and even small movement of vessel cause the - to oscillate. It is very difficult to take readings

A

dry card compass

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15
Q

is made of mica and has about 15 cm india meter. The card is attached to a nickel-silver float chamber that has a sapphire cap. The cap rests on iridium tipped pivot. The sapphire has a polishing effect on the iridium tip

A

wet card

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16
Q

The movement of the card is dampened by filling the bowl with mixture liquid consisting of —- (this is to stop the liquid freezing in extremely cold weather)

A

distilled water and part pure ethyl alcohol

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17
Q

The mixture of distilled water and pure alcohol has the following properties

A

,(a) Low freezing point about -30 ̊C
(b) Small coefficient of expansion
(c) Does not discolour the card
(d) Low relative density about 0.93

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18
Q

The — increases or decreases in volume as necessary, as the liquid in the bowl expands or contracts due to changes in atmospheric temperature

A

chamber

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19
Q

Mariners using a compass of this type have to make an allowance in their steering, and this allowance differs not only from place to place but also from year to year (because the magnetic poles slowly alter their positions).

A

variation

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20
Q

the magnetic compass is affected by the magnetism of the ship itself and this error is the

A

deviation

21
Q

a Point-magnetic compass capable of being made to point true north and using the directional property of a free gyroscope

A

marine Gyro Compass

22
Q

are more complicated than the magnetic compass, reliable and accurate

A

Marine gyro Compasses

23
Q

directional signals can be inputted into an automatic steering system thus allowing the ship to be steered in the required direction without continuous human effort

A

gyro Compass

24
Q

In case the ship is installed with a –the auto steering can be re-connected to the magnetic compass via the transmitting system and the ship can continue on her voyage on the autopilot

A

Transmitting Magnetic Compass (TMC),

24
Q

is fitted on top of the binnacle and is non-ferrous.

A

helmet

25
Q

This is in place to protect the compass bowl from the weather and
harsh conditions

A

helmet

26
Q

is housed on the monkey island and the compass course needs to be viewed from the bridge

A

magnetic compass

27
Q

is in place to enable the same via subsequent reflections.

A

compass projector

28
Q

It is in place to enable the helmsman to in the wheelhouse to view the coincident compass card reading and lubber line to steer the ship correctly

A

compass projector

29
Q

may be tested for pivot friction by deflecting the compass cards a few degrees.

A

compass card

30
Q

A device usually fitted in the centre of the compass bowl for the purpose of supporting the directional system, while allowing the latter to rotate freely.

A

pivot

31
Q

container made of non-magnetic material and designed to house the directional system of a compass

A

bowl

32
Q

device designed to support the compass bowl and to allow it freedom of movement about the fore-and-aft and the thwartship axes of the ship, so that the suspended compass is permitted to seek a horizontal position regardless of the ship’s motion.

A

gimbals

33
Q

compass is kept horizontal by the use of a — moving freely on an axis, within which it swings on an axis at right angles

A

gimbal, or ring

34
Q

mark against which the compass heading is read. It is situated inside the compass bowl and normally fitted in the vertical plane of the fore-and-aft gimbal axis

A

index

35
Q

The magnetism induced in the steel by the earth’s magnetic field causes the compass needle to – from the magnetic meridian, by an amount which is called the

A

deviation

36
Q

Deviation is named – if the compass needle points to the left of the magnetic meridian,

A

west

37
Q

deviation is named – if the compass needle points to the right of the magnetic meridian.

A

east

38
Q

the direction of the magnetic meridian is called .

A

Magnetic North

39
Q

The direction indicated by the compass needle is called the

A

Compass North

40
Q

It has its own magnetic field that can effect changes in the ship’s magnetic compass▪ Determined by angle in which the Keel is laid during initial construction▪ Equipment – electronics can also cause deviation▪ Expressed in Degrees East and West (rounded to nearest.5 Degree)▪ Changes with the ship’s heading

A

deviation

41
Q

Each ship is made of

A

Steel and Iron

42
Q

actual error of the compass at any time will be the combination of the

A

variation and the deviation.

43
Q

the difference between True North and Magnetic North.

A

Variation-

44
Q
  • the difference between Magnetic North and Compass North
A

DEVIATION

45
Q
  • the direction of the north geographical pole.
A

True North

46
Q
  • the direction of the magnetic meridians at anyplace.
A
  1. Magnetic North
46
Q

the angle at the observer between the direction of True North and the direction being measured, measured clockwise from North.

A

True Course or Bearing-

46
Q
  • the direction indicated by the north point of the compass.
A
  1. Compass North
47
Q
  • the angle at the observer between the direction of magnetic meridian and the direction being measured, measured clockwise from North
A

Magnetic Course or Bearing

48
Q
  • the angle at the observer between the direction of compass north and the direction being measured, measured clockwise from North
A

Compass Course or Bearing

49
Q
A

First Semester (BSMT) (22 decks)

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