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1 Lab 17-1 ONLINE LESSON

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

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

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4 Do take notes as we peruse through this lesson…

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5 Azimuth and Distance

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

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

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

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9 Place a protractor on the surface of our planet.

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

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11 “N” stands for north!

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12 North is a reference on our planet.

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13 Now we can find an azimuth…

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

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

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16 The azimuth is 35° true

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

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18 From the green star to the blue star…

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19 The back azimuth is 215° true

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

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

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

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23 We can find azimuths using maps and charts…

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

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25 Maps represent land…

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26 Charts represent the ocean…

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

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

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29 A B

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

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

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34 Place a protractor on the chart…

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

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

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39 Then read the azimuth…

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41 The azimuth is 120° true…

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42 Distances can be determined from maps and charts…

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

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44 scale

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45 The scale represents 2 nautical miles.

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46 scale 1 nautical mile (nm)

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47 scale 1 nautical mile (nm)

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48 scale 2 nautical miles (nm)

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

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50 The length should be about 9.2 cm

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51 Use this relationship… 1nm 9.2 cm

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

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

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54 Then measure the line in centimeters…

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

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56 1nm 9.2cm x 29cm = Solve for “X”…

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

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

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

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60 Ask Bob for Lab 17-1Q questions

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61 END L17-1

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