Glossary · Sailing & navigation
Great circle
Also called: Orthodromie, orthodromique, route orthodromique, great circle route, loxodromie, rhumb line
The shortest path between two points on the globe, which looks curved on a chart.
On a sphere, the shortest route follows the arc of a great circle. On an ordinary chart (Mercator projection) it looks curved, whereas a straight line is a constant heading, the rhumb line, which is longer.
Race distances to finish and average speeds are usually computed along the great circle: a boat that makes a big detour actually sails many more miles than the official distance.