🔍 Key Concepts

• Relative motion along a straight track when your course and speed are constant • How changing bearings over time relate to your track line and closest point of approach (CPA) • Using time and speed to convert between distance run and distance off at abeam

💭 Think About

• From 1914 to 1951, how long have you been traveling, and how many miles have you covered at 15 knots? • If you plot your course line and then plot the two observed bearings from the same fixed light, what geometric figure do you get? How does the point where the bearing would be exactly 90° to your course relate to distance off? • Think about whether the distance off abeam depends more on the absolute bearings, or on the change in bearing over the distance you run

✅ Before You Answer

• Compute the time interval between the two bearings carefully in minutes, then convert to hours before multiplying by 15 knots • Make sure you draw or imagine the correct true bearings from the light to your track, not from your ship to the light • Check that your final distance off abeam is less than the total distance run between the two observations (it cannot be greater)