You are steaming on a course of 084°T at a...

Question 1 of 2707066636ee928f7522a1c51a1a0

You are steaming on a course of 084°T at a speed of 13 knots. At 1919 a lighthouse bears 106.5°T. At 1957 the same lighthouse bears 129°T. What will be your distance off the lighthouse when abeam?

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Question 1 of 27070

You are steaming on a course of 084°T at a speed of 13 knots. At 1919 a lighthouse bears 106.5°T. At 1957 the same lighthouse bears 129°T. What will be your distance off the lighthouse when abeam?

🔍 Key Concepts

• Relative motion and change of bearing to a fixed object • Using speed and elapsed time to calculate distance run • Constructing a running fix or calculating distance off when abeam from two bearings ahead

💭 Think About

• How far did you travel between the first and second bearings, and how can that form one side of a triangle? • If the lighthouse will be abeam at 90° relative bearing, where is that point on your track compared to the two observed bearings? • How can you use the difference in bearings to find the angles of a right or oblique triangle and solve for the perpendicular distance from your track to the lighthouse?

✅ Before You Answer

• Convert the time interval between 1919 and 1957 to hours accurately, then compute distance run = speed × time • Sketch the ship’s track and the two bearings from the lighthouse and clearly label the angles at the lighthouse and along your track • Confirm which side of the triangle represents the distance off when abeam (perpendicular distance from your course line), not the distance along track