On 6 April your 0300 DR position is LAT 27°42'S, LONG 128°58'W. You are on course 097°T at a speed of 18 knots. You observed 3 celestial bodies. Determine the latitude and longitude of your 0600 running fix.
• Dead reckoning (DR) track from 0300 to 0600 on course 097°T at 18 knots • How a running fix shifts from the DR position using LOPs (lines of position) advanced along the track • Expected distance run in 3 hours at 18 knots and how that affects latitude and longitude
• First, compute how many miles you travel between 0300 and 0600, then visualize (or sketch) that movement from the initial DR position on course 097°T. • Think about whether your latitude should increase or decrease on a course of 097°T in the Southern Hemisphere, and whether your longitude should move east or west. • Compare the direction and approximate size of that DR advance with each answer choice to see which one is consistent with the track and distance run.
• Verify the distance run using: Distance = Speed × Time, with time in hours. • Check that the change in longitude is reasonable for the run on 097°T at that latitude (remember 1° of longitude is less than 60 NM at this latitude). • Confirm that the signs and trends make sense: are you moving toward or away from the equator (latitude) and toward a smaller or larger W longitude on an easterly course?
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