Compasses (Bridge management) Flashcards

1
Q

Where is the magnetic compass placed? (2)

A

Monkey island on the top of the ship.
Away from large pieces of metal.(ferrous materials)

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2
Q

List the five carriage requirements under SOLAS Ch V Magnetic compass.

A
  • A properly adjusted standard magnetic compass independent of any power supply.
  • A pelorus or compass bearing device independent of any power supply
  • Means of correcting heading and bearing to true at all times
  • A spare magnetic compass interchangeable with the magnetic compass
  • A properly adjusted transmitting heading device to transmit heading information for input to specified equipment
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3
Q

What is a gyro compass?

A

A gyrocompass is a type of non-magnetic compass which is based on a fast-spinning disc and the rotation of the Earth to find geographical direction automatically

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4
Q

When should magnetic compasses be adjusted? (5)

A
  • When ship is built
  • Undergoes structural repairs/modification that could affect compass
  • Electronic equipment is added/removed that could affect the compass
  • The compass becomes unreliable
  • Every 2 years except when regular compass errors taken
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5
Q

Will magnetic properties of a vessel change over time?

A

Yes

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6
Q

Can magnetic properties of a ship be affected by cargo?

A

Yes

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7
Q

Who must a compass be adjusted by?

A

Certified compass adjuster

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8
Q

What is the construction of the liquid compass?

A

Bowl is brass with clear glass top and frosted glass bottom (to allow card to be illuminated from below)
Expansion ring is fitted to bowl with a filling cap on the side

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9
Q

Why is the card smaller than the bowl (liquid compass)

A

To keep it clear of turbulence created around edge of bowl as the ships swings

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10
Q

What is the liquid compass bowl mounted in?

A

Gimbals within a binnacle

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11
Q

Gimbal

A

Pivoted support that permits rotation of an object about an axis

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12
Q

What is the binnacle?

A

The house of the compass

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13
Q

What is the binnacle made of?

A

Non-magnetic materials

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14
Q

What does the binnacle need to be clear of?

A

Anything that may alter its magnetic fields.

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15
Q

How are air bubbles removed from the binnacle?

A

Injecting distilled water

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16
Q

Define hard magnetic material

A

Those which if comes under the influence of of magnetic field become permanent magnets

17
Q

Define soft magnetic material

A

Those which when comes under magnetic field become magnets and lose their magnetism as soon as the magnetic field is removed

18
Q

What is the azimuth mirror/ring?

A

A device for taking compass bearings

19
Q

What is a pelorus?

A

used for taking relative bearings of objects when compass bearings cannot be taken

20
Q

What is the first law of magnetism?

A

Like poles repel each other; unlike poles attract each other

21
Q

What is the second law of magnetism?

A

The force between two poles varies directly as the product of their pole strengths and inversely as the square of the distance between them.

22
Q

Define variation

A

The angle between the magnetic and true meridian

23
Q

Define deviation

A

The angle between the compass needle and the magnetic meridian

24
Q

Define compass error

A

The combined effect of variation and deviation