Introduction to Types of Charts: Gnomonic, Polyconal, and Mercator Projection Basics
A basic understanding of the types of chart projections is helpful to understand the basic coastal cruising charts you are most likely to encounter for sailing. Here’s a brief rundown on the three main projections, with a few pro’s and con’s and when they are most likely to be utilized. Different projects are more advantageous for different uses. The chart projection type you choose for a long around-the-world voyage will be different from one you use to navigate into a harbor.