You desire to make good a true course of 132°. The variation is 10°W, magnetic compass deviation is 5°E, and gyrocompass error is 5°W. A northeast by east wind produces a 5° leeway. What is the course to steer per standard magnetic compass to make the true course good?
• True–Magnetic–Compass–Per Standard Compass conversion sequence • How variation (W/E) and deviation (W/E) algebraically affect course conversions • Effect of leeway and from which side the wind is blowing (relative to your course)
• Start from the desired true course and work step-by-step toward per standard magnetic compass; list each intermediate heading (true, gyro, magnetic, compass). • Decide whether each correction (variation, deviation, gyro error, leeway) should be added or subtracted based on whether it is east or west and whether you are going from true to compass or the reverse. • Think about a northeast by east wind: relative to a course of about 132°T, will the wind push your bow to the right (starboard) or to the left (port), and do you steer into or away from the wind to compensate?
• Confirm you are solving for course to steer per standard magnetic compass, not true or gyro course. • Check that you applied the correct sign (add vs subtract) for 10°W variation, 5°E deviation, and 5°W gyro error when going from true to compass. • After you apply leeway, verify whether your final steered course should be greater than or less than the desired true course given the wind direction.
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