Berrie
Jetboaters Commander
- Messages
- 424
- Reaction score
- 657
- Points
- 187
- Location
- Kansas City, MO
- Boat Make
- Monterey
- Year
- 2001
- Boat Model
- Other
- Boat Length
- 31
VHF band transmissions need both antennae to “see” each other with little obstruction. A 1000’ tower is sufficient to overcome the earth’s curvature over a distance of 39 miles. If the boat’s antenna is 10’ high that adds 4 miles.FYI... Before my return crossing with an unknown engine durability issue I called tow boat us in ft Lauderdale... They said they have a 1000 foot tower they use for their vhf radio... They said many times they can talk to bimini or stleast near the island... Could be bs but that's what they said! That's a hell of a tower!
However, line of sight is not the only factor. Radio wave propagation on VHF (FM/AM) is also heavily dependent on transmission power (unlike HF where LSB and USB bounces in the ionosphere requiring very little power; sometimes as little as 5W to reach Australia).
As many here have noticed, with a low power handheld you can receive many, but only few can receive you - in part due to lack of line-of-sight, but mostly due to lack of power. With 25W on VHF the max distance you can transmit is about 40 miles, give or take 15 depending on weather.
It works going to Bimini. But going to West End, about halfway out your VHF won’t be able to reach the mainland anymore.