VHF radios are line-of-sight communication devices that will only transmit 5-10 miles depending on the unit and if there is an external antenna. Some sailboats equipped with antennas on their masts can transmit and receive longer distances. While this short range communication is good for localized chatter, Coast Guard stations can both transmit and receive over longer distances because of the height of their towers. Handheld VHF radios with transmission power of 6W will transmit over longer distances than units with only 5W for example. When choosing the best VHF unit, remember that when deciding between fixed mounted (up to 25W) or the more mobile versions.