On 15 July your vessel is enroute from Portland, OR, to Singapore, Malaysia. You are steering course 243°T and making a speed of 16 knots. Your 1845 zone time DR is LAT 27°42.0'N, LONG 167°02.0'E. You observed 3 celestial bodies. Determine the latitude and longitude of your 1945 running fix.
• Dead reckoning (DR) track and running fix – how to advance LOPs (Lines of Position) from earlier sights to a common time • Speed–time–distance relationships to advance LOPs one hour forward along the course steered • Effect of course 243°T and 16 knots on both latitude and longitude over one hour at about 27°N
• From 1845 to 1945, how far will the vessel travel at 16 knots, and in what true direction relative to north and west? • At a latitude of about 27°N, will a course of 243°T increase or decrease your latitude, and increase or decrease your longitude (E or W)? • Looking at the answer choices, which ones show the position moved in the correct general direction and by a realistic amount for one hour of steaming?
• Compute and sketch the DR advance: Distance = Speed × Time and lay it off on course 243°T from the 1845 DR position • At 27°N, verify that 1 minute of longitude < 1 NM, and think about whether a 16‑NM move could reasonably change longitude by the amount shown in each choice • Check that the final latitude and longitude in your chosen option both move in the correct sense (north/south and east/west) compared to the 1845 DR and the direction of the DR track
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