MARINE COMMUNICATIONS
Marine equipment for communications is divided into several specific types. These include the long-range, ship-to-ship/ship-to-shore radiotelegraph, very high frequency (VHF) bridge-to-bridge voice communications, single-sideband (SSB) ship-to-shore communications, and satellite communications (satcom). It should be recognized that some of the other equipment is the responsibility of the radio officer according to the organization of a particular commercial operation. More and more, however, voice communication systems are under the control and responsibility of the deck officer.
VHF Bridge-to-Bridge Radio
Marine VHF is usually found between 156.00 MHz and 162.00 MHz. Frequencies are broken down into a series of channels from 1 through 89. (Not all of these channels are in use and have designated frequencies.) Channels are either simplex (transmitting and receiving on the same frequency); or duplex (transmitting on one frequency and receiving on another frequency). Simplex is usually designated for U.S. use (or suffixed with "A"), and duplex is normally designated for international use.
Each channel has a specific use and all marine frequencies are regulated in the United States by the Federal Communications Commission, and regulated worldwide by international agreement. The international calling and distress frequency for VHF is channel 16 (156.800 MHz). The U.S.Coast Guard monitors channel 16 and utilizes several designated working frequencies. Marine radio operator service is also located in coastal, harbor, and river areas on specified working frequencies. The National Weather Service (through NOAA) maintains weather information services near the marine radio band for use by mariners. All VHF radios are capable of picking up these frequencies, which include channels 29 (162.55 MHz) and 89 (162.40 MHz).
