How Far Can Marine Radios Transmit Land to Land?by Bud Maxwell
Communicating by radio on land was a craze in the 1970's. Both private passenger cars and professional truckers used the inexpensive, limited-range Citizens Band transmissions to avoid speeding tickets and to pass the time while logging highway miles. Today no license is required to operate a CB radio, but the device has practically disappeared from passenger vehicles. VHF marine radios are more powerful, but their use ashore could land users in hot water with the FCC.
A license to operate a CB is no longer needed. But CB radios have only 4 watts of carrier power at most, allowing clear reception over distances of not much more than five miles. And the range is limited by "line of sight," the unobstructed path between sending and receiving antennas. Mountainous terrain can reduce CB range to just a few hundred yards.
VHF Marine Radios
VHF marine radios are considerably more powerful than CB radios. They are vital for sailors to communicate with other vessels, harbor masters, bridge operators, marinas and rescue services. The United States Coast Guard monitors Marine channel 16 (156.8 MHz,) the international calling and distress channel. The maximum output for a VHF marine radio, also regulated by the FCC, is 25 watts, giving an open water range of up to 60 nautical miles.
Use on Land
Marine radios function no differently than CB radios, as their reception is governed by line of sight. On the high seas, of course, there are no hills or trees to interfere with transmission, although heavy fog can have the same limiting affect. Recreational boaters who navigate large lakes, where terrain definitely plays a role, may find their radios not much better than a CB.
A license is needed to operate a marine radio, and the class of license for a land-based radio is especially restrictive. Since marine radios are at electronic lifeline offshore, the FCC strictly regulates their use. Under optimum conditions, a marine radio boosting 25 watts of power would obviously transmit and receive much further than a CB. Given that a Marine radio can receive for up to 60 nautical miles, it's conceivable on flat land that the distance would be nearly the same.
In 2005, the FCC filed a criminal complaint against a hunter in Florida after tracking his VHF marine transmission to a radio installed in his pickup truck. The hunter admitted to using the marine frequency for hunting purposes, claiming the more powerful radio increased his ability to receive transmissions from other hunters. His $10,000 fine was reduced to $650 due to his inability to pay based on his tax return.
- photo_camera Image by Flickr.com, courtesy of Duncan Rawlinson