That's why it's prudent to lessen your risk by taking preventive action that includes slowing to a safe speed, energizing your navigation lights and sounding the appropriate sound signals for your vessel type, as required by the Navigation Rules, available online through the Coast Guard Navigation Center at navcen
Coast Guard will make an announcement ahead of time via the "Broadcast Notice to Mariners" on VHF Channels 16 and 22, and the "Local Notice to Mariners," available at navcen
.uscg.gov under "Current Operational/Safety Information."
Government agencies have developed a network of transmitting towers that provide a free differential correction signal, the most popular being the Coast Guard (CG) NAVCEN
(Navigation Center) system.