Maptech Waterproof Chart #WPC042. he Maptech Waterproof Charts have a unique flip-fold design folds down to a small size that is easy to store and carry, and it opens up to show popular cruising areas. Spread a chart out to its full width, or keep it folded and flip to your favorite area. Measures 24 inches x 36 inches when fully opened, 6 inches x 12 inches when folded. .