The correct answer is C) weather maps and local knowledge. The National Weather Service (NWS) provides weather advisories and forecasts, but these should be used in conjunction with other weather information sources, such as weather maps and local knowledge of the area, to get a more comprehensive understanding of the weather conditions. Weather maps can provide additional details on weather patterns, fronts, and other relevant information that supplements the NWS advisories. Local knowledge, such as historical weather trends and patterns in the specific area, can also be valuable in interpreting and applying the NWS weather information. The other options are incorrect because tide tables and tidal current tables (A) provide information on water levels and currents, which are not directly related to the weather information provided by the NWS. The local Notice to Mariners (B) contains information on navigational hazards and changes, but does not provide comprehensive weather data. While the U.S. Coast Pilot (D) contains valuable information for mariners, it is not a primary source for weather data like the NWS advisories and weather maps.