If you make good this course at 12.5 knots until you are close abeam Thimble Shoal Channel Lighted Buoy R"2”, then change course to 288°T, what time will you pass between Trestle “A” and Trestle “B”?
• Time-Speed-Distance relationship at 12.5 knots • Using the chart to measure distance from the buoy R"2" to the line between Trestle “A” and Trestle “B” along course 288°T • Starting from your time abeam R"2" (from the previous step in the problem) and adding the run time for the second leg
• On your chart, trace the 288°T leg from Thimble Shoal Channel Lighted Buoy R"2". Where does this track cross the line between Trestle “A” and Trestle “B”? • How many nautical miles is it from the buoy R"2" to that crossing point, measured along 288°T? • At 12.5 knots, how many minutes does it take to travel that distance, and what clock time do you get when you add that to your time abeam R"2"?
• Confirm you are measuring along the 288°T course line, not straight between the features • Convert distance to time using ( \text{Time (hours)} = \frac{\text{Distance (NM)}}{12.5,\text{kn}} ), then into minutes • Add that run time to your previously calculated time abeam R"2" and check that the result matches one of the choices to the nearest minute
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