Why Ships Communicate

Ships and other vessels at sea need to communicate with each other and with the shore for various purposes, such as navigation, safety, and coordination. There are different methods and systems for marine communication, such as:

- VHF radio, which is a line-of-sight radio that can be used for ship-to-ship and ship-to-shore communication within a range of about 20 to 30 nautical miles. VHF radio can also be integrated with Digital Selective Calling (DSC), which is a system that allows remote control commands to transmit or receive distress, urgent, safety, or routine messages.
- Cell phone, which is a convenient device that can be used for contacting land-based people and businesses. However, cell phones have limited range, reliability, and battery power on the water, and they depend on the availability of cell towers and signals. Cell phones should be used in tandem with a VHF radio.
- Family Radio Service (FRS) radio, which is a personal, non-commercial radio that can be used for short-range communication on land or water. FRS radios operate in the UHF band and transmit at 0.5 watts. They have no emergency channel and limited battery power. They are useful for communicating within a boat or between nearby boats.
- CB radio, which is a public access radio that can be used for communication on land or water. CB radios operate in the HF band and have 40 channels, except channel 9 which is reserved for emergencies. CB radios have a range of about five miles and are not very common on boats.
- Satellite communication, which is a system that uses geostationary satellites to transmit and receive signals over long distances and beyond the line-of-sight. Satellite communication can provide two-way communication, data transmission, navigation, weather information, and emergency alerts. Satellite communication services are provided by INMARSAT and COSPAS-SARSAT.
- Sound or visual signaling, which is a method of communication that uses sound or light signals to convey messages or instructions. Sound signals include whistles, horns, bells, gongs, sirens, and guns. Visual signals include flags, semaphores, flares, lanterns, searchlights, and fireworks. Sound or visual signaling can be used for identification, navigation, warning, distress, or coordination.

These methods and systems can help to facilitate marine communication and enhance maritime safety.