🔍 Key Concepts

• Magnetic variation (declination) and how it is shown on nautical charts • The purpose and content of a compass rose on a chart • Different ways a chart can provide magnetic information besides symbols on the chart face

💭 Think About

• Think about all the places on a chart where information about Earth’s magnetic field and compass corrections might be described or summarized. • Ask yourself: does the chart provide magnetic information only with symbols and lines, or are there also written notes and diagram details? • Consider how a navigator would quickly find the current magnetic variation and annual change when first opening a chart.

✅ Before You Answer

• Look at what is commonly shown inside the compass rose (inner vs. outer ring information). • Recall what isogonic lines represent and whether they are related to magnetic variation over an area. • Remember that many charts include marginal notes or boxes explaining magnetic variation and annual change—verify whether this counts as magnetic information.