Very High Frequency (VHF)

A range of radio frequencies from 30 MHz to 300 MHz, commonly used in marine communication for short-range, line-of-sight transmissions.

Very High Frequency (VHF) is a critical component of maritime communication, providing a reliable and efficient means for vessels to communicate with each other, shore stations, and maritime authorities. The VHF spectrum is divided into channels, with specific channels designated for particular purposes, such as distress calls, ship-to-ship communication, harbour operations, and weather updates. For example, Channel 16 (156.8 MHz) is universally reserved for distress, safety, and calling purposes, serving as the primary frequency for emergency communication.

VHF signals travel in straight lines, meaning they are limited to line-of-sight transmission. This characteristic makes them highly effective for short-range communication, typically up to 20-30 nautical miles, depending on the height of the antenna and atmospheric conditions. The simplicity and reliability of VHF radios make them indispensable for both commercial and recreational mariners. Modern VHF radios often include features such as Digital Selective Calling (DSC), which allows users to send automated distress signals with their vessel’s location, and Automatic Identification System (AIS) integration, which aids in collision avoidance.

In addition to communication, VHF is also used for navigation and safety purposes, such as receiving Notices to Mariners and real-time weather forecasts. Its widespread adoption and standardisation ensure that mariners worldwide can rely on a common communication platform, enhancing safety and coordination at sea.