You are steaming on a course of 211° T at 17 knots. At 0417 a light bears 184° T, and at 0428 the same light bears 168° T. What is the distance off the light at 0428?
• Plotting two position lines (bearings) of the same fixed light while steaming on a steady course and speed • Using the run between the two bearings to form a triangle and find distance off at the later bearing • Converting time at a given speed into distance run along track
• How far did you travel between 0417 and 0428 at 17 knots, in nautical miles? • If you plot your track (211° T) and the two bearings (184° T and 168° T) from the light, what kind of triangle is formed between the light, your 0417 position, and your 0428 position? • Once the triangle is drawn, which side of that triangle represents the distance off at 0428, and which angle or sides do you know that will let you solve for it?
• Be sure you convert 11 minutes of time to hours correctly before computing distance run: ( \text{Distance} = \text{Speed} \times \text{Time} ) • Check that the bearings you plot are from the light to the ship, not from the ship to the light, and that you use true bearings consistently • Verify that the side you solve for in your triangle is the one perpendicular (or nearly perpendicular) to your line of bearing at 0428, representing the distance off the light at that moment
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