Your vessel is steering 157° T at 18 knots. At 2018 a light bears 208° T. At 2044 the same light bears 232° T. What will be your distance off when abeam?
• Convert the true bearings of the light to relative bearings from your ship’s heading • Use your speed and the time between bearings to find the distance run along your track • Apply a right triangle / trigonometry (sine law) idea to relate distance run to distance off when the light is abeam (90° off your bow)
• What are the angles between your course (157° T) and each of the observed bearings (208° T and 232° T)? Are these on the port or starboard bow? • How far does your vessel travel between 2018 and 2044 at 18 knots, in nautical miles? • If you draw your track and the two lines of bearing to the light, what kind of triangle is formed, and how will that help you project ahead to the point where the light will be exactly abeam (90°)?
• Be sure you convert time to hours correctly before multiplying by 18 knots • Double-check that you are using angles off the bow (relative bearings), not the true bearings, in your triangle/trig setup • Before choosing an answer, confirm that your final distance off is reasonable compared to the distance run between 2018 and 2044
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