🔍 Key Concepts

• Use Mercator sailing: work in a right triangle formed by difference of meridional parts and departure, not just plain difference of latitude. • Determine the quadrant of the course first from the changes in latitude and longitude (are you going N/S and E/W?). • Compute difference of meridional parts from a nautical table for each latitude, and departure from the difference of longitude and mean latitude.

💭 Think About

• From 32° 16.6' N to 43° 12.2' N, are you going generally north or south? From 68° 28.0' W to 55° 39.0' W, are you going east or west? What quadrant does that put your true course in? • How does Mercator sailing use the right triangle where one side is the difference of meridional parts and the other is the departure to find the course angle? • Once you have the course angle, how can you use it with the change in latitude to find the rhumb‑line distance and see which distance choice is reasonable?

✅ Before You Answer

• Confirm whether the course must be in the NE, NW, SE, or SW quadrant before you look at the numeric bearings. • Check that the distance is consistent with about 11° of latitude change (roughly 60 NM per degree of latitude). • Verify that you used meridional parts, not just plain difference of latitude, when relating the triangle sides to get the course.