Frequency band (Marine VHF)

The marine VHF band is the very-high-frequency range, about 156 to 162 MHz, that carries short-range ship-to-ship, ship-to-shore, and port voice and DSC traffic. ITU Radio Regulations Appendix 18 sets the channel plan: channels are spaced 25 kHz, with the international channels and their simplex or duplex use defined there. Channel 16 sits at 156.800 MHz for distress and calling, channel 70 at 156.525 MHz for DSC only. VHF works by line of sight, so range is roughly 20 to 30 nautical miles to a coast station and less between low ships, which is why it defines GMDSS sea area A1. Output is normally 25 W, reducible to 1 W in harbor.