Navigate Using a Map and Compass Course: BMQ (P Res) EO: 012.01 b Name: Navigate Using a Map and Compass Using a Compass Compass Description and Characteristics Magnetic Declination and Annual Change Definition and Types of North Time: Reference: B-GL-382-005/PT-002

Navigate Using a Map and Compass Using a Compass Compass Description and Characteristics Magnetic Declination and Annual Change Definition and Types of North TP

Navigate Using a Map and Compass Compass Description and Characteristics Calibrated in mils Easy to use Accurate Mounted on a transparent plastic baseplate Has a cover with a sighting mirror and sight Includes romers at 1:25 000 and 1:50 000 scales in metres Compass needle is white at the south end and red with a luminous patch at the north end

Navigate Using a Map and Compass Compass Description and Characteristics Graduated from 0 to 6400 mils Rotated by hand, and inside there is a series of meridian lines parallel to the 0–3200 mils axis An arrow on the central meridian always points to 0 on the dial Dial may be set to any desired bearing, the reading being taken at the index pointer The sighting arrow, index pointer, sighting mirror and line, and the sight are used to align the compass on the objective. This line marks the axis of the compass or line of travel.

Navigate Using a Map and Compass Compass Description and Characteristics

Do you have any questions?

Q1: The dial is graduated in what units?

A1: The dial is graduated in mils.

Q2: The dial is graduated from ZERO mils to…?

A2: It is graduated from 0 to 6400 mils.

Q3: Name the parts of the compass.

A3:

Navigate Using a Map and Compass Using a Compass Compass Description and Characteristics Magnetic Declination and Annual Change Definition and Types of North TP

Navigate Using a Map and Compass Magnetic Declination Due to dynamic forces on the Earth the Magnetic North continually migrates, subsequently an annual adjustment calculation must be made to obtain the correct Grid Magnetic Angle at the date of observation. The amount of adjustment, to be made, is provided in the diagram (or written information) on north points, as discussed in paragraph 24. For example, using the values given in Figure 7-9, if the observation is made in 1975, the grid magnetic angle at that date would be calculated as follows:

Navigate Using a Map and Compass Magnetic Declination Figure 7-9: Conversion of Bearings

Navigate Using a Map and Compass Change in angle from 1970 to 1975 = number of years X annual change = 5 × 1 mil = 5 m EAST This is to say that, Magnetic North has moved 5 mils towards the east, and therefore, in this case, the grid magnetic angle has become smaller by this amount. Hence, the grid magnetic angle in 1975 was 45-5 = 40 mils.

Navigate Using a Map and Compass Grid Bearings/Magnetic Bearings To convert a grid bearing to a magnetic bearing, or vice versa, one must first refer to the north points diagram and obtain the Grid Magnetic Angle (the angle between Grid and Magnetic North) and adjust it for annual change. Next, remembering that all bearings are measured clockwise from their north point, it is clear from the above example (figure 7-9) that the magnetic bearing will be greater than the corresponding grid bearing by the amount of the grid magnetic angle. Therefore, in the above example, to convert a 1975 grid bearing to a magnetic bearing, one had to add the grid magnetic angle of 40 mils to the grid bearing. Conversely, to convert a magnetic bearing to a grid bearing, one had to subtract 40 mils from the magnetic bearing.

Navigate Using a Map and Compass Grid Bearings/Magnetic Bearings Figure 7-10: Grid North is East of Magnetic North (Grid Bearing = Magnetic Bearing—Grid Magnetic Angle)

Navigate Using a Map and Compass Grid Bearings/Magnetic Bearings Where the magnetic north is east of Grid North, this note reads “ADD” in lieu of “SUBTRACT”. This is shown in Figure 7-11. If working in degrees, the information on the map is given in degrees as well as in mils (See figure 7-9) and the same principles apply. In the example given in paragraph 25, the grid magnetic angle in degrees in 1975 is 2° 30' – (5 X 3') = 2° 15'. This is added to the grid bearing in degrees or subtracted from the magnetic bearing in degrees as in paragraph 26.

Navigate Using a Map and Compass Grid Bearings/Magnetic Bearings Figure 7-11: Grid North is West of Magnetic North (Grid Bearing = Magnetic Bearing + Grid Magnetic Angle)

Navigate Using a Map and Compass Magnetic Declination and Annual Change Annual Magnetic Change The magnetic pole varies in position. The amount by which its direction changes annually (i.e. the annual change in the grid magnetic angle) is called the annual magnetic change. This must be taken into account when converting magnetic bearings to other bearings or vice versa.

Do you have any questions?

Q1: Find the magnetic angle of a 2001 map if the current year is 2004 with an annual change of 4′ west and a grid magnetic angle of 17 degrees 54′.

A1: 18 degrees 06′.

Navigate Using a Map and Compass Using a Compass Compass Description and Characteristics Magnetic Declination and Annual Change Definition and Types of North TP

Navigate Using a Map and Compass Definition and Types of North True North is the direction of the North Pole. Grid North is the direction of the north-south grid lines on a map. Magnetic North is the direction in which a compass needle points when free from error or disturbance.

Do you have any questions?

Q1: What are the three types of north?

A1: Magnetic North Grid North True North

Navigate Using a Map and Compass Using a Compass Compass Description and Characteristics Magnetic Declination and Annual Change Definition and Types of North TP

Do you have any questions?

Navigate Using a Map and Compass Question 1 The dial is graduated in what units? Question 2 The dial is graduated from ZERO mils to…? Question 3 What are the three types of north? 05/04/2002 09:46 EO 108.01 - # 32 COURSE DP1 - INFANTRYMAN

Navigate Using a Map and Compass Answer 1 The dial is graduated in mils. Answer 2 It is graduated from 0 to 6400 mils. Answer 3 Magnetic North, Grid North, True North 05/04/2002 09:46 EO 108.01 - # 33 COURSE DP1 – INFANTRYMAN

Navigate Using a Map and Compass Course: BMQ (P Res) EO: 012.01 b Name: Navigate Using a Map and Compass Using a Compass Compass Description and Characteristics Magnetic Declination and Annual Change Definition and Types of North Time: Reference: B-GL-382-005/PT-002