You are steering 349°T, and a light is...

Question 1 of 31048fy_heal_CREATE_q371_2027

You are steering 349°T, and a light is picked up dead ahead at a distance of 17.2 miles at 2122. You change course to pass the light 4.5 miles off abeam to port. If you are making 19.5 knots, what is your ETA at the position 4.5 miles off the light?

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Question 1 of 31048

🔍 Key Concepts

• Relative motion along the original track versus the abeam point • Using the right triangle formed by your track and the closest point of approach (4.5 miles off) • Relationship between distance ahead, CPA distance, and time-speed-distance calculations

💭 Think About

• What is the straight-line distance you will travel from the point you first see the light until you are 4.5 miles abeam of it? • How can you use the 17.2-mile range and 4.5-mile abeam distance to form a right triangle and find the distance along your track? • Once you know the distance to travel along your course, how do you convert that distance to time at 19.5 knots and add it to 2122 to find the ETA?

✅ Before You Answer

• Confirm that the 17.2 miles is the initial slant range from your vessel to the light when first sighted dead ahead • Use Pythagorean theorem with the CPA (4.5 miles) as one side and the distance along track as another side of the right triangle • Check your time = distance/speed calculation carefully and convert decimal hours to minutes before choosing the ETA option