🔍 Key Concepts

• Set and drift of current and how to compute an estimated course to steer (CTS) • Using radar ranges to fix your present position and then plotting a drifted track line to the desired point abeam of Endeavor Shoals Gong Buoy • Converting between true course and gyrocompass course, assuming a known gyro error or that gyro = true if not given

💭 Think About

• How do the radar ranges to Race Rock Light and Latimer Reef Light allow you to plot an accurate fix on the chart? Once you have that fix, where is the point where the buoy will bear 270°T at 1.5 miles? • If the current is 080°T at 1.5 knots and you want a certain course over ground to pass the buoy abeam at the correct distance, in which general direction will the current push you relative to that desired track? • When you lay out your desired track line, how do you use the current vector and your intended speed through the water to find the single course to steer that will cancel the set and drift?

✅ Before You Answer

• Make sure you clearly mark your 2030 fix using the radar ranges before drawing any track lines. • Draw the desired ground track from your fix to the point where the buoy bears 270°T at 1.5 miles, and measure that track’s true course first. • Construct a current triangle (or vector triangle): one side is your ship’s speed through the water, one side is the current (080°T at 1.5 kn), and the resulting side must lie along your desired track. Then measure the required course to steer and compare it with the answer choices.