To convert your true course to magnetic course, you should ____ westerly variation.

To convert your true course to magnetic course, you should ____ westerly variation.

• A. Add
• B. Subtract
• C. Ignore
• D. Multiply

Answer: (A)

To convert your true course to a magnetic course, you need to adjust for magnetic variation, which is the difference between true north and magnetic north. When you have a westerly variation, it indicates that magnetic north is to the west of true north. Thus, to convert the true course to magnetic course, you must subtract the westerly variation from your true course. Westerly variation is considered a negative adjustment because it requires you to move clockwise back towards true north. Therefore, if the true course is stated, subtracting the westerly variation results in the correct magnetic course. This adjustment takes into account the fact that, with a westerly variation, the magnetic course will be less than the true course.

To convert your true course to a magnetic course, you need to adjust for magnetic variation, which is the difference between true north and magnetic north. When you have a westerly variation, it indicates that magnetic north is to the west of true north. Thus, to convert the true course to magnetic course, you must subtract the westerly variation from your true course.

Westerly variation is considered a negative adjustment because it requires you to move clockwise back towards true north. Therefore, if the true course is stated, subtracting the westerly variation results in the correct magnetic course. This adjustment takes into account the fact that, with a westerly variation, the magnetic course will be less than the true course.