VHF marine radio

A VHF marine radio is an essential communication tool aboard vessels, operating within the Very High Frequency maritime mobile band between 156.000 MHz and 174.000 MHz using frequency modulation (FM). Unlike land-mobile or aviation VHF equipment, marine radios follow international channel plans defined by the International Telecommunication Union (ITU). Signal propagation relies on line-of-sight transmission, meaning effective communication ranges typically span from 5 to 30 nautical miles (9 to 55 km), directly governed by antenna height above the waterline. Transmitter power is regulated at 25 watts for fixed-mount radios (with a low-power 1-watt setting) and up to 5 or 6 watts for handheld units.

According to Wikipedia, Channel 16 VHF (156.800 MHz) is a marine VHF radio frequency designated as an international distress, urgency, and safety frequency. It is monitored continuously to handle distress calls (Mayday, Pan-Pan) and initiate contact before moving to working channels. Skippers call on designated working channels (such as VHF 09 or 68) when arranging berth docking at a yacht marina or receiving navigational notices and marine weather forecast updates. Modern VHF transceivers incorporate Class D Digital Selective Calling (DSC), enabling automated distress alerts sent alongside GPS coordinates.