🔍 Key Concepts

• Great circle vs rhumb line behavior on long east–west voyages • Meaning of a vertex on a great circle track in the Northern Hemisphere • Relationship between course quadrant and the actual directions sailed between two given positions

💭 Think About

• Look at the great circle track between Jacksonville and the Strait of Gibraltar on the chart: does the latitude change significantly, or stay almost the same? How would that affect the difference between a great circle and a rhumb line? • Identify approximately where the vertex (highest latitude point) of the great circle track would lie relative to your route. Are you ever west or east of that point during the voyage? • Check the initial, middle, and final true courses along the track. Do they all fall into the same compass quadrant, or do they change quadrants as you proceed across the Atlantic?

✅ Before You Answer

• Verify the change in latitude between Jacksonville and the Strait of Gibraltar and how that affects great circle vs rhumb line separation. • Verify the location of the Northern Hemisphere vertex for the great circle track and whether your entire route lies east or west of it. • Verify the true courses at departure, mid-ocean, and approach to Gibraltar to see if they all lie in the northeast quadrant or not.