From Wikipedia, the free encyclopedia.
A rhumb line (or loxodrome) is a path of constant bearing on a spherical (or elliptical) object. They are a traditional part of the theory of navigation.
If you follow a given (magnetic-deviation compensated) compass-bearing on Earth, you will be following a rhumb line, which spirals from one pole to the other, never actually reaching the poles. (Rhumb lines aren't defined at the poles.)
Contrast with: great circle, small circle.
On a Mercator projection map, a loxodrome is a straight line. On a stereographic projection map, a loxodrome is an equiangular spiral whose center is the North (or South) pole.
On a sphere which has coordinates φ (azimuth) and θ (latitude), the equation of a loxodrome is
The word "loxodrome" comes from Greek loxos : oblique + dromos : running (from dramein : to run).
Old maps do not have grids composed of lines of latitude and longitude but instead have rhumb lines which are: directly towards the North, at a right angle from the North, or at some angle from the North which is some simple rational fraction of a right angle. These rhumb lines would be drawn so that they would converge at certain points of the map: lines going in every direction would converge at each of these points. See compass rose.
