How do you convert true heading to compass course?

To convert true heading to compass course, you need to account for magnetic declination, which is the angle between true north and magnetic north. First, determine the local magnetic declination value, which can be positive (east) or negative (west). Then, adjust the true heading by adding or subtracting the declination: if the declination is east, subtract it from the true heading; if west, add it. The resulting value will give you the compass course.