What is the communications coverage for Rescue 21 using a 1 watt radio and a 2 meter antenna?

• A. 10nm Seaward
• B. 20nm Seaward
• C. 30nm Seaward
• D. 40nm Seaward

Answer: (B)

Radio coverage is driven by line-of-sight, which depends on antenna height and transmitter power. With a 1-watt transmitter and a modest 2-meter antenna on the VHF band, the signal can reach across open water only so far before the curvature of the Earth and signal loss reduce readability. In practice, that setup yields about 20 nautical miles seaward of coverage under typical conditions.

Ranges around 10 nautical miles would be shorter than what this hardware typically supports, while 30 or 40 nautical miles would require more power or a taller antenna to maintain a reliable signal. So the practical, typical seaward coverage for Rescue 21 with these settings is about 20 nautical miles.