In article ,
Harry Krause wrote:

With my VHF tranmitting at 25 watts, I can easily reach out from one
side of Chesapeake Bay to the other in most places.

At the 1 watt setting, who knows?

For the sake of discussions, let's say on a clear day from my VHF
antenna, which is approximately 14' above the waterline, a 25 watt
transmission reaches someone 12 miles away with a similar antenna height.

Is there a way to figure how far a 1 watt setting will reach with the
same equipment?

It's entirely dependent on the noise on the channel and each boat's
quality of setup. Working with friends on an unusual channel at 1w, we
reliably communicated from HdeG to Georgetown on the Sassafras. They had
a 6db antenna at deck level, ours is 3db 40 feet up. There was some
terrain between us, so we proved that VHF is not strictly line of sight.

--
Jere Lull
Xan-a-Deux ('73 Tanzer 28 #4 out of Tolchester, MD)
Xan's Pages: http://members.dca.net/jerelull/X-Main.html
Our BVI FAQs (290+ pics) http://homepage.mac.com/jerelull/BVI/