Print On Demand, (POD) is one means of providing NOAA nautical chart information to the mariner in a fast efficient manner. The POD process entails the use of large format inkjet or electrostatic plotters to produce nautical charts. The Office of Coast Survey (OCS) has been experimenting with this technology as one possible way to provide mariners with more up-to-date charts. Under this approach, OCS would update digital files of all charts each week for all Notice to Mariner items. Then, using print-on-demand, charts would be printed when ordered using these updated files. . The standard Print-On-Demand charts are water-resistant with a tough coating for longer life. Bright colors make them easier to read under varying light conditions. However, these charts can be ordered four ways: comes as a convenient 7′ x 12′ tri-fold. Length varies by chart number. Tri-fold is only available for resistant charts. – there is a limited list of antique charts, some over 100 years old, which are printed on quilted quality fine-art paper Bathymetric charts provide the submerged equivalent of above-water topographic maps. They are designed to present an accurate, measurable description and visual presentation of the submerged terrain. Source.