MCA CoC Navigation & Chart Work

Question 1

What is the difference between True North, Magnetic North, and Compass North?

Accepted Answer

True North is geographic north; Magnetic North is where the compass points due to the Earth's field; Compass North includes instrument deviation

Answer

True North is the direction of the geographic North Pole. Magnetic North is where the Earth's magnetic field points the compass needle and varies from True North by variation (declination). Compass North is further affected by the ship's own magnetic field, called deviation.

Question 2

What is 'variation' on an Admiralty chart?

Accepted Answer

The angular difference between True North and Magnetic North at a given location and time

Answer

Variation is the angular difference between True North (geographic) and Magnetic North at any given point on the Earth's surface. It varies by location and changes slowly over time due to shifts in the Earth's magnetic field. It is shown on Admiralty charts.

Question 3

What is 'deviation' in compass navigation?

Accepted Answer

The error in a ship's compass caused by the vessel's own magnetic field and ferrous material on board

Answer

Deviation is the error in a compass caused by the magnetic influence of the vessel's own steel structure, electrical systems, and ferrous items on board. It varies with the ship's heading and must be assessed using a deviation card.

Question 4

A vessel's compass reads 045°C and deviation for the heading is 3°W. What is the Magnetic heading?

Accepted Answer

042°M

Answer

To convert Compass to Magnetic: apply deviation. Westerly deviation is subtracted from compass heading. 045° - 3° = 042°M. The mnemonic 'Compass to True — add East' (or subtract West) guides the conversion.

Question 5

What is a 'fix' in coastal navigation?

Accepted Answer

A positional determination obtained by crossing two or more position lines from observed bearings, landmarks, or electronic systems

Answer

A fix is a definite position obtained by crossing two or more position lines simultaneously or near-simultaneously. Multiple bearings of charted objects, radar ranges, or electronic position data are used to determine the vessel's position with confidence.

MCA CoC Practice Test

MCA CoC Practice Test

MCA CoC Navigation & Chart Work