You desire to make good a true course of 157°. The variation is 15°E, magnetic compass deviation is 9°W, and gyrocompass error is 3°E. A southwesterly wind produces a 2° leeway. What is the course to steer per standard magnetic compass to make the true course good?
• True, Magnetic, Compass (T–M–C) relationships when both variation and deviation are given • How to correctly apply gyro error (E/W) and convert between gyro course and true course • Effect of a southwesterly wind on leeway and which way the vessel is pushed
• Start from the desired true course and work step‑by‑step through gyro, magnetic, and compass, being careful with the East is least, West is best idea and the sign of each correction • Think about where a southwesterly wind comes from and which side of your bow it will push you toward, then decide whether to add or subtract the leeway from your steered course • When going from true to compass, make a small table of headings (T, G, M, C, psc) and fill each line carefully so you don’t mix up which corrections are applied in which direction
• Be clear on the direction of leeway: does a southwesterly wind cause you to drift to port or starboard relative to your heading? • Double‑check the signs of variation, deviation, and gyro error (E or W) and whether you are converting to or from true when you apply them • Confirm that your final answer is a per standard compass (psc) course and that you have already allowed for leeway in the course you steer
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