🔍 Key Concepts

• True north vs magnetic north on a nautical chart and compass rose • Difference between variation and deviation • What compass error is actually made up of

💭 Think About

• Look at a compass rose on a chart: which labeled value shows how far magnetic north is from true north, and what is that called? • Think about where deviation comes from—does it come from the Earth’s magnetic field, or from the vessel itself? • Is compass error a single basic quantity, or is it the combination of two other errors?

✅ Before You Answer

• Identify which term refers specifically to the Earth’s magnetic field difference between true and magnetic north • Confirm which term is caused by magnetic influences on board the vessel • Remember that compass error = variation ± deviation, so which one in the list matches only the true–magnetic difference?