At 2207 Cape Charles Light bears 276°T, Chesapeake Light bears 194°T, and Cape Charles Lighted Bell Buoy "14" bears 312°T and is 2.0 miles off. What were the set and drift of the current acting on your vessel from 2129 to 2207?
• Set and drift: Set is the direction the current pushes you toward (in °T), drift is the speed of that current (in knots). • Plotting DR (dead reckoning) position vs. fixes to see how far and in what direction the current moved you over time. • Using the time interval from 2129 to 2207 (in minutes) to convert miles of current-caused displacement into knots.
• First, think about where your DR position would be at 2207 if there were no current, based on your ordered course and speed from 2129. • Then compare that DR position with your fix at 2207 (from the bearings given) to find the displacement vector due to current: which direction did it move you, and how far? • Once you know the distance the current moved you and the time interval (2129–2207), convert that distance per hour into knots, and express the direction as a true bearing (set).
• Be sure you are measuring the direction the current carried you TOWARD (set), not where it came from. • Double-check the time difference between 2129 and 2207 and convert it correctly into hours before finding drift in knots. • Confirm that your measured displacement from DR to fix matches one of the magnitude–direction pairs in the answer choices (both the bearing and the speed must agree).
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