🔍 Key Concepts

• Polaris azimuth methods for finding compass error • How the Nautical Almanac is used with Polaris • Difference between GHA (Greenwich Hour Angle) and LHA (Local Hour Angle), and what each one needs as input

💭 Think About

• Ask yourself: when you use Polaris to check your compass, do you start from a global reference (Greenwich) or something tied to your own longitude (local)? • Think about which angle (GHA or LHA) the Almanac actually tabulates directly, and which one you usually have to compute from your DR (dead reckoning) position. • For a Polaris problem, what specific hour angle do you need in order to find the bearing of Polaris from your ship?

✅ Before You Answer

• Identify whether the Almanac pages for Polaris are entered with a time-based quantity (like GHA) or a position-based quantity (like LHA). • Recall that LHA = GHA − Longitude (or the equivalent form). Which of the choices already includes that local component? • Verify which of the four options is the one you would actually use to look up data in the Nautical Almanac tables for Polaris, not the one you compute after entering.