Navigation Method: Rhumb Lines and Great Circle

Different methods are available for calculating the distance and bearing between any two points on a chart.

The great circle route is the shortest path between two points. However, if you are to travel along such a route, it would be difficult to steer manually as the heading would constantly be changing (except in the case of due north, south, or along the equator).

Rhumb lines are tracks of constant bearing. It is possible to travel between two locations using Rhumb line computation, but the distance would usually be greater than if Great circle is used.

The map projection used by Navionics is Navionics Mercator. This projection will overlay with Google and Bing maps except when you get close to the north and south poles.