These easy-to-use, compact chart books are ideal for daysailors, fishing boats, and trailer boats. They measure 12" x 17" (24" x 17" when open) and are made of waterproof, tear-resistant synthetic paper that will withstand the elements. GPS Ready: New features make Waterproof Chartbooks easy to use with your GPS. Most charts include one-minute Lat/Lon grids to make vessel positioning a breeze, and major navigation aids are identified with named GPS waypoints. Small- and Large-Scale Charts: Waterproof Chartbooks include small-scale, wide area charts as well as large-scale, detailed charts of harbors and approaches. The Chart Page Index (on the front cover) and “Go-Tox9D page numbers make it simple to find the chart you want. Pre-Plotted Courses: Maptechs navigation editors add magnetic courses between major navigation aids with distances in nautical miles. Chartbooks are also designed to help you do the calculations yourself. Each page includes a compass rose with annual increase in variation and complete scale information.