Scout Americas

Marine VHF Range Calculator

Last updated: July 2026

VHF radio range is line-of-sight: roughly 1.23 × √(antenna height in feet) nautical miles per station, added together. Move the sliders to see your realistic range — and why antenna height beats wattage every time.

Antenna tip height: mount height + antenna length. A center console T-top with an 8ft antenna ≈ 16ft.

Another boat ≈ 10–15ft. Coast Guard shore towers ≈ 100–300ft.

8.5 NM
Maximum ship-to-ship range (nautical miles)
9.8 mi
Statute miles
17 NM
Estimated range to a 100ft Coast Guard tower
Recommended antenna: With 12ft of mounting height, a 6dB 8ft antenna maximizes your radiated signal at the horizon — see the Scout KS-42 or the collinear Scout KS-43.

How the Radio Horizon Formula Works

VHF signals at 156–162 MHz travel in nearly straight lines and do not follow the curvature of the earth. Your effective range is the distance to your radio horizon plus the distance to the other station's horizon:

Range (NM) ≈ 1.23 × √h₁ + 1.23 × √h₂   (h in feet)

The 1.23 coefficient includes standard atmospheric refraction, which bends VHF slightly beyond the visual horizon. Real-world results vary with sea state, atmospheric ducting, and — critically — installation quality: corroded connectors and cheap coax can cut your effective radiated power in half.

Example Ranges

ScenarioAntenna HeightsApprox. Range
Two center consoles12 ft / 12 ft8.5 NM
Center console to sportfish flybridge12 ft / 30 ft11 NM
Boat to Coast Guard shore station12 ft / 100 ft16.5 NM
Sailboat masthead to shore station50 ft / 100 ft21 NM
Full Range GuideFind Your Antenna