What is the true course to steer between the entrance to Winnapaug Pond (LAT 41°19.6'N, LONG 71°45.8'W) and the entrance to Lake Montauk (LAT 41°04.8'N, LONG 71°56.3'W), if you are turning for 6.5 knots, allow for a current of 295°T at 0.9 knot, and an easterly wind is causing 4° of leeway?
• Plotting the rhumb line between two positions using latitude and longitude • Constructing a current triangle to account for set and drift with your intended speed • Applying leeway caused by wind to get from course made good to course steered
• First, what is the true course between the two entrances if there were no current and no wind? How do you find that from the two positions on the chart? • Once you know your course made good and speed through the water, how do you combine the vessel’s velocity vector with the current vector to find the course to steer? • An easterly wind causes leeway in which direction? Should the leeway angle be added or subtracted from the course you found after allowing for current?
• Be sure you are using true directions (°T) for both current set and course, not magnetic or compass • Confirm that the current set (295°T) and drift (0.9 kn) are drawn correctly in direction and scale relative to your ship’s 6.5 kn vector • Check that you apply the 4° leeway on the correct side of the course: think carefully about where the bow must point to keep the actual track along the intended line
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