🔍 Key Concepts

• Compass error as the total difference between what the compass reads and the actual true direction • The definitions of variation (difference between true and magnetic) and deviation (error caused by the vessel’s own magnetism) • The common memory aid: "True Virgins Make Dull Company" (TVMDC) and where compass error fits in that chain

💭 Think About

• First, write out the TVMDC line (True–Variation–Magnetic–Deviation–Compass) and think about where each term applies • Ask yourself: Does compass error compare true to magnetic, or true to compass, or magnetic to compass? • Consider whether compass error should be expressed as a single combined angle that already includes both variation and deviation

✅ Before You Answer

• Confirm the definition of variation: is it between true and magnetic, or true and compass? • Confirm the definition of deviation: is it between magnetic and compass, or true and magnetic? • Check which choice, if any, clearly describes the total angular difference between true and what your compass actually shows