Gnomonic map

The gnomonic chart is a specialized nautical chart where all great circle routes (orthodromes) appear as straight lines. It is particularly useful for planning the shortest paths between two points on the Earth’s surface, especially for long ocean crossings. However, angles and coastline shapes are highly distorted, making it less practical for precise course-following in local navigation. Mariners primarily use the gnomonic chart to plot segments of great circles, which are then transferred onto a Mercator chart for easier navigation along a constant compass course. It serves as an essential complement to conventional charts, helping optimize the planning of maritime routes.