NavList:

Comparison of surface areas of Africa and Greenland is not a primary purpose of a map. The primary purpose in navigation is determining your course from A to B. When A and B are at a moderate distance (say one or two days of sailing) a straight line on a Mercator map gives you a nearly optimal compass setting (corrected for deviation, of course). For this purpose they were always used for navigation and still are used. If you care about fuel economy over a very long distance, you can lay your course on orthofromy using a special map, and then break it into straight pieces and use the same Mercator map every day for plotting your position.

For polar navigation one can use special maps (stereographic projection).

Comparison of areas or Greenland and Africa (or of Russia and US) is a business of politicians, and has nothing to do with navigation,

Alex.