VHF Marine Radio

[searchlight]

How far from the transmitting vessel could you expect to pick up a voice call using a good vhf marine radio?
Thanks

[seadogg]

VHF is supposed to be line of sight We live 300 feet above the North Sea and I can read Humber shipping O.K 40 plus miles away via a 40 foot high antenna..
Power has an effect too and so do the conditions. In a "lift" or period of tropospheric ducting my 26 watts has worked stations in Norway. If you are land based a multi element antenna will extend you coverage in a given direction.

[Buenchico]

VHF radio is basically 'line of sight', so the range is greatest when both the transmitter and receiver have aerials mounted well above sea level (and, of course, when higher powers are used). The following quotes illustrate my point:

From Wikipedia:
"Transmission power ranges between 1 and 25 watts, giving a maximum range of up to about 60 nautical miles (111 km) between aerials mounted on tall ships and hills, and 5 nautical miles (9 km) between aerials mounted on small boats at sea-level".
http://en.wikipedia.org/wiki/Marine_VHF_radio

From a company which provides training leading to the relevant radio operator's licence:
"Marine VHF is the best way of summoning help. You can contact the coastguard up to 50 miles off-shore and talk to other yachts up to 15 to 20 miles on the open sea"
http://www.yachtcom.info/

That seems to be largely consistent with my own experiences of monitoring ship-to-shore communications from the Felixstowe Port viewing point:
http://www.theanswerb.../Question1065967.html

Chris

[seadogg]

Just one other point. Coastguard stations often relay messages thereby extending the effective range of vessels. Our lifeboat whip aerial is mounted a few feet above the waterline but the local coastguard station is used to extend this. The government, in its wisdom, wants to chop most CG stations.