To complicate matters a bit, in the HF frequency range of SSB radio communications, certain frequency ranges are allocated for marine use (thus called “marine bands”) while other frequency ranges are reserved for amateur radio usage (generically called “ham bands”). In order to communicate on these frequencies, most yachts today use a “single sideband,” or SSB, radio that both receives and transmits - a so-called “transceiver.” SSB is simply the way in which the wave is transmitted that results in a tightly compacted signal, which allows the radio wave to travel thousands of miles. These frequencies, under certain circumstances, can be used to propagate radio waves over very long distances, even completely around the globe, which is why HF radio is an important communications conduit for yachts at sea. HF, by contrast, refers to frequencies in the range of 3 MHz to 30 MHz. AIS units use VHF frequencies of 161.975 MHz and 162.025 MHz.
The frequency of 156.800 MHz is the VHF frequency of channel 16, the agreed-upon international distress, safety and calling channel that is programmed into all marine VHF radios. VHF radio waves are used in VHF radios and AIS units. and a high-frequency single sideband (HF SSB) transceiver for long-range digital and voice communications. These are: a very high frequency (VHF) transceiver for voice communications over a short distance (<20 nm) an Automatic Identification System (AIS) receiver or AIS receiver/transponder for digital communications using VHF frequencies of a ship’s identity, position, course, speed, etc. Most cruising yachts today carry three radios that are important for ship-to-ship and ship-to-shore communications. Given the regularity of these requests, we thought it good to try to demystify the subject of high-frequency (HF) radio communications aboard a cruising yacht with an emphasis on the comparison of marine versus amateur frequencies.
We are often asked by those planning to set sail and go voyaging if we can help them sort through the myriad of details about voice and digital communications aboard.