Navigation and Seamanship

1.2.13. Rhumb lines

For practical purposes, a rhumb line (also known as loxodromes or loxodromic spirals) can be defined as a line which crosses every meridian of the sphere at the same angle. In other words, a ship may maintain a true heading without change from starting point to destination (if, for the moment, one disregards factors such as currents, wind and changing magnetic variation).