1 Lab 17-1 ONLINE LESSON

2 If viewing this lesson in Powerpoint Use down or up arrows to navigate

3 If viewing this lesson in Flash Use the control bar to navigate

4 Do take notes as we peruse through this lesson…

5 Azimuth and Distance

6 An azimuth is a compass direction from one point to another…

7 To use azimuth…a reference point must be established…

8 The north pole of Planet Earth can be used as a reference point.

9 Place a protractor on the surface of our planet.

10 The “N” of the protractor matches the “N” of our planet…

11 “N” stands for north!

12 North is a reference on our planet.

13 Now we can find an azimuth…

14 From the middle of the protractor…where the blue star resides

15 To the green star…is an azimuth…a compass direction.

16 The azimuth is 35° true

17 A back azimuth is just an azimuth in the opposite direction…

18 From the green star to the blue star…

19 The back azimuth is 215° true

20 Adding 180° to 35° produces a back azimuth of 215.

21 RULE #346: If an azimuth is 180° or less…then add 180 ° for a back azimuth

22 RULE#9999: If an azimuth is 181 or more…then subtract 180 for a back azimuth

23 We can find azimuths using maps and charts…

24 A map or a chart is a small graphical representation of the surface of the planet…

25 Maps represent land…

26 Charts represent the ocean…

27 To find an azimuth on a map or chart… two locations are needed…

28 An origination point (A) and a destination point (B)…

29 A B

30 Mark 2 locations on the chart with a green dry erase marker…

31

32 With a green dry erase marker draw a line between the 2 points……

33

34 Place a protractor on the chart…

35

36 Make sure that the protractor’s north/south axis is aligned with the north/south axis of the chart…

37

38 The north/south axis of the protractor must be parallel with the north/south axis of the chart…

39 Then read the azimuth…

40

41 The azimuth is 120° true…

42 Distances can be determined from maps and charts…

43 There is a distance scale on the San Francisco Bay chart …it is located at the top of the chart.

44 scale

45 The scale represents 2 nautical miles.

46 scale 1 nautical mile (nm)

47 scale 1 nautical mile (nm)

48 scale 2 nautical miles (nm)

49 With a ruler, measure the length of a 1 nautical mile segment of the distance scale…

50 The length should be about 9.2 cm

51 Use this relationship… 1nm 9.2 cm

52 To determine the distance between two points on a chart…

53 Draw a line with a dry erase marker between 2 points…

54 Then measure the line in centimeters…

55 If the line is 29 cm… use the relationship… 1nm 9.2 cm

56 1nm 9.2cm x 29cm = Solve for “X”…

57 The distance on the chart is 3.2 (nautical miles) nm

58 Referring to page 5 of Lab 62, a metric distance can be calculated…

59 This same ratio is seen on the Metrics at a Glance reference guide…

60 Ask Bob for Lab 17-1Q questions

61 END L17-1