As a mariner, you need reliable data for safe navigation. Therefore, the Hydrographic Service publishes nautical charts and nautical publications. Since the situation at sea changes continuously, you are required to keep these products up to date. You can do so by using the Notices to Mariners (NtMs). In the 'NtMs-database' you can select the changes to each nautical chart by week number or chart number. You can also incorporate the changes by means of a weekly downloadable file on the page 'Overview weekly editions'. Changes in nautical publications are on the page 'Corrections to nautical publications'.
Every coastal state is obliged to chart its coastal waters and make these data available. As a mariner, you must use these official nautical products. This obligation ensues from the International Convention for the Safety of Life at Sea (SOLAS Convention).