🔍 Key Concepts

• Difference between true bearings, magnetic bearings, and relative bearings • Purpose of a pelorus and how it is mounted and used on a vessel • How a compass card can be used without actually having a magnet or north-seeking function

💭 Think About

• Which instrument listed is specifically designed to work with a ship’s compass repeater to measure relative bearings from the ship’s heading, not from north? • Which option is essentially a compass-like card that you can manually align with the ship’s heading, so it doesn’t need its own north-seeking ability? • Look at each choice and ask: Is this primarily an optical sight, an attachment that fits on a compass, or a standalone relative bearing instrument?

✅ Before You Answer

• Identify which device uses a graduated circular card that you can rotate and align with the ship’s heading • Eliminate any device that is primarily just a sighting device (no compass card of its own) • Confirm which option is commonly used on small vessels without a gyro or magnetic repeater to take bearings relative to the bow (0° at the ship’s head)