630. A vessel at LAT 28°20'N, LONG 16°00'W is to proceed to LAT 21°00'N, LONG 18°00'W. What is the course and distance by mid-latitude sailing?

Mid-latitude sailing yields a course of 194T and a distance of 453 miles. Departure is calculated as DLo multiplied by the cosine of the mid-latitude, and the course is determined by the tangent of the departure divided by the change in latitude. The distance is found using the Pythagorean theorem.