You sighted Trestle "A" in line at 0707 and are steering 108°T. At 0731, Cape Henry Light bears 136°T; Cape Charles Light bears 032.5°T; and Thimble Shoal Tunnel South Light bears 282°T. What was the speed made good between 0707 and 0731?
• Speed = Distance / Time relationship and converting minutes to hours • Using a running fix / position lines to determine distance run between two known positions • Reading and measuring distances on the chart scale between positions at 0707 and 0731
• How can you use the bearings given at 0731 to plot your position, knowing your course steered since 0707? • Once you have the 0707 line of position (LOP) and the 0731 fix, how do you measure the distance between those two positions on the chart? • After finding the distance in nautical miles, how do you convert the 24-minute time interval to hours to calculate speed in knots?
• Be sure you’re measuring distance in nautical miles between the 0707 and 0731 positions, not along a bearing line that doesn’t represent your track. • Confirm that 24 minutes = 0.4 hours before doing the speed calculation. • Double-check that the plotted 0731 position uses all three bearings correctly to form a three‑line fix before measuring distance.
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